High Pressure Processing of Fruit and

Vegetable Products

Contemporary Food Engineering

Series Editor

Professor Da-Wen Sun, Director Food Refrigeration & Computerized Food Technology

National University of Ireland, Dublin (University College Dublin)

Dublin, Ireland http://www.ucd.ie/sun/

Advances in Heat Transfer Unit Operations: Baking and Freezing in

Bread Making, edited by Georgina Calderón-Domínguez, Gustavo

F. Gutiérrez-López, and Keshavan Niranjan (2016) Innovative Processing Technologies for Foods with Bioactive Compounds, edited

by Jorge J. Moreno (2016) Light Scattering Technology for Food Property, Quality and Safety Assessment, edited

by Renfu Lu (2016) Edible Food Packaging: Materials and Processing Technologies, edited by Miquel

Angelo Parente Ribeiro Cerqueira, Ricardo Nuno Correia Pereira, Oscar

Leandro da Silva Ramos, Jose Antonio Couto Teixeira, and Antonio Augusto

Vicente (2016) Handbook of Food Processing: Food Preservation, edited by Theodoros Varzakas

and Constantina Tzia (2015) Handbook of Food Processing: Food Safety, Quality, and Manufacturing

Processes, edited by Theodoros Varzakas and Constantina Tzia (2015) Advances in Postharvest Fruit and Vegetable Technology,

edited by Ron B.H. Wills and John Golding (2015) Engineering Aspects of Food Emulsification and Homogenization,

edited by Marilyn Rayner and Petr Dejmek (2015) Handbook of Food Processing and Engineering, Volume II: Food Process

Engineering, edited by Theodoros Varzakas and Constantina Tzia (2014) Handbook of Food Processing and Engineering, Volume I: Food Engineering

Fundamentals, edited by Theodoros Varzakas and Constantina Tzia (2014) Juice Processing: Quality, Safety and Value-Added Opportunities, edited by

Víctor Falguera and Albert Ibarz (2014) Engineering Aspects of Food Biotechnology, edited by José A. Teixeira

and António A. Vicente (2013) Engineering Aspects of Cereal and Cereal-Based Products, edited by Raquel de

Pinho Ferreira Guiné and Paula Maria dos Reis Correia (2013) Fermentation Processes Engineering in the Food Industry, edited by Carlos

Ricardo Soccol, Ashok Pandey, and Christian Larroche (2013) Modified Atmosphere and Active Packaging Technologies, edited by

Ioannis Arvanitoyannis (2012) Advances in Fruit Processing Technologies, edited by Sueli Rodrigues and

Fabiano Andre Narciso Fernandes (2012)

Biopolymer Engineering in Food Processing, edited by Vânia Regina Nicoletti

Telis (2012) Operations in Food Refrigeration, edited by Rodolfo H. Mascheroni (2012)

Thermal Food Processing: New Technologies and Quality Issues, Second Edition, edited by Da-Wen Sun (2012)

Physical Properties of Foods: Novel Measurement Techniques and

Applications, edited by Ignacio Arana (2012) Handbook of Frozen Food Processing and Packaging, Second Edition,

edited by Da-Wen Sun (2011) Advances in Food Extrusion Technology, edited by Medeni Maskan and

Aylin Altan (2011) Enhancing Extraction Processes in the Food Industry, edited by Nikolai Lebovka,

Eugene Vorobiev, and Farid Chemat (2011) Emerging Technologies for Food Quality and Food Safety Evaluation,

edited by Yong-Jin Cho and Sukwon Kang (2011) Food Process Engineering Operations, edited by George D. Saravacos and

Zacharias B. Maroulis (2011) Biosensors in Food Processing, Safety, and Quality Control, edited by Mehmet

Mutlu (2011) Physicochemical Aspects of Food Engineering and Processing, edited by

Sakamon Devahastin (2010) Infrared Heating for Food and Agricultural Processing, edited by Zhongli Pan and

Griffiths Gregory Atungulu (2010) Mathematical Modeling of Food Processing, edited by Mohammed M. Farid (2009)

Engineering Aspects of Milk and Dairy Products, edited by Jane Sélia dos Reis Coimbra and José A. Teixeira (2009)

Innovation in Food Engineering: New Techniques and Products, edited by Maria

Laura Passos and Claudio P. Ribeiro (2009) Processing Effects on Safety and Quality of Foods, edited by Enrique Ortega-

Rivas (2009) Engineering Aspects of Thermal Food Processing, edited by Ricardo Simpson

(2009) Ultraviolet Light in Food Technology: Principles and Applications, Tatiana

N. Koutchma, Larry J. Forney, and Carmen I. Moraru (2009) Advances in Deep-Fat Frying of Foods, edited by Serpil Sahin and Servet Gülüm

Sumnu (2009) Extracting Bioactive Compounds for Food Products: Theory and Applications, edited

by M. Angela A. Meireles (2009) Advances in Food Dehydration, edited by Cristina Ratti (2009) Optimization

in Food Engineering, edited by Ferruh Erdoˇgdu (2009) Optical Monitoring of

Fresh and Processed Agricultural Crops, edited by Manuela Zude (2009)

Food Engineering Aspects of Baking Sweet Goods, edited by Servet Gülüm

Sumnu and Serpil Sahin (2008) Computational Fluid Dynamics in Food Processing, edited by Da-Wen Sun (2007)

High Pressure Processing of Fruit and

Vegetable Products

Edited by

Milan Houska

Filipa Vinagre Marques da Silva

CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2017 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed on acid-free paper International Standard Book Number-13: 978-1-4987-3902-3 (Hardback) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have

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Contents

Series Preface .......................................................................................................... ix Series Editor ............................................................................................................ xi Editors ................................................................................................................... xiii Contributors ............................................................................................................xv

Chapter 1 Introduction to High-Pressure Processing of Fruit and Vegetable Products ...............................................................................................1

Milan Houska and Filipa Vinagre Marques da Silva

Chapter 2 High-Pressure Processing Effect on Microorganisms in Fruit and Vegetable Products .......................................................................3

Filipa Vinagre Marques da Silva and Evelyn

Chapter 3 High-Pressure Processing Effects on Endogenous Enzymes in Fruits and Vegetables ....................................................................39

Netsanet Shiferaw Terefe and Roman Buckow

Chapter 4 Packaging System for High-Pressure Processing ...............................63

Jaroslav Dobiáš and Lukáš Vápenka

Chapter 5 Current Status of Industrial HPP Equipment for Food Processing ....73

Francisco Purroy Balda

Chapter 6 High-Pressure Processing Effect on Nutrients and Their Stability ....85

Concepción Sánchez-Moreno and Begoña De Ancos

Chapter 7 Health Active Components in Fruit/Vegetable Juices Treated by High Pressure .............................................................................. 105

Jan Tříska

Chapter 8 Sensory Properties of High-Pressure Treated Fruit and Vegetable Juices ........................................................................ 121

Pui Yee Lee and Indrawati Oey

vii

viii Contents

Chapter 9 High-Pressure Processing Combined with Heat for Fruit and Vegetable Preservation ............................................................. 135

Ariette Matser and Martijntje Vollebregt

Chapter 10 Examples of Commercial Fruit and Vegetable Juices and Smoothies Cold Pasteurized by High Pressure ......................... 147

Milan Houska and Petr Pravda

Chapter 11 Regulatory Aspects of High-Pressure Processed Foods in North America, Europe, Asia, New Zealand, and Australia ...................... 155

Tatiana Koutchma and Keith Warriner

Chapter 12 Conclusions and Final Remarks ........................................................ 169

Milan Houska and Filipa Vinagre Marques da Silva

Index ..................................................................................................................... 173

Series Preface

CONTEMPORARY FOOD ENGINEERING Food engineering is the multidisciplinary field of applied physical sciences combined

with the knowledge of product properties. Food engineers provide the technological

knowledge transfer essential to the cost-effective production and commercialization of

food products and services. In particular, food engineers develop and design pro-cesses

and equipment to convert raw agricultural materials and ingredients into safe, convenient,

and nutritious consumer food products. However, food engineering top-ics are

continuously undergoing changes to meet diverse consumer demands, and the subject is

being rapidly developed to reflect market needs. In the development of food engineering, one of the many challenges is to employ

modern tools and knowledge, such as computational materials, science, and nano-

technology, to develop new products and processes. Simultaneously, food quality

improvement, safety, and security continue to be critical issues in food engineer-ing

studies. New packaging materials and techniques are being developed to pro-vide

more protection to foods, and novel preservation technologies are emerging to

enhance food security and defense. Additionally, process control and automation

regularly appear among the top priorities identified in food engineering. Advanced

monitoring and control systems are developed to facilitate automation and flexible

food manufacturing processes. Furthermore, energy-saving and the minimization of

environmental problems continue to be important food engineering issues, and sig-

nificant progress is being made in waste management, efficient utilization of energy,

and reduction of effluents and emissions in food production. The Contemporary Food Engineering Series, consisting of edited books, attempts

to address some of the recent developments in food engineering. The series covers

advances in classical unit operations in engineering applied to food manufacturing

as well as topics such as progress in the transport and storage of liquid and solid

foods; heating, chilling, and freezing of foods; mass transfer in foods; chemical and

biochemical aspects of food engineering and the use of kinetic analysis; dehydration,

thermal processing, nonthermal processing, extrusion, liquid food concentration,

membrane processes, and applications of membranes in food processing; shelf-life

and electronic indicators in inventory management; sustainable technologies in food

processing; and packaging, cleaning, and sanitation. These books are aimed at pro-

fessional food scientists, academics researching food engineering problems, and

graduate-level students. The editors of these books are leading engineers and scientists from different parts

of the world. All the editors were asked to present their books to address the market’s

needs and pinpoint cutting-edge technologies in food engineering.

ix

x Series Preface

All contributions are written by internationally renowned experts who have both

academic and professional credentials. All authors have attempted to provide criti-

cal, comprehensive, and readily accessible information on the art and science of a

relevant topic in each chapter, with reference lists for further information. Therefore, each book can serve as an essential reference source to students and

researchers in universities and research institutions.

Da-Wen Sun Series Editor

Series Editor

Prof. Da-Wen Sun, born in southern China, is a global

authority in food engineering research and education; he is a

member of the Royal Irish Academy (RIA), which is the

highest academic honor in Ireland; he is also a member of

Academia Europaea (The Academy of Europe), one of the

most prestigious academies in the world, a fellow of the

International Academy of Food Science and Technology, and

a fellow of International Academy of Agricultural and

Biosystems Engineering. He is also the founder and editor- in-chief of Food and Bioprocess Technology, one of the most prestigious food science

and technology journals; the series editor of “Contemporary Food Engineering” book

series with already about 50 volumes published; and the founder and president of the

International Academy of Agricultural and Biosystems Engineering (iAABE). In

addition, he served as the president of the International Commission of Agricultural and

Biosystems Engineering (CIGR), the world’s largest organization in the field, in 2013–

2014, where is now an honorary president. He has contributed significantly to the field

of food engineering as a researcher, academic authority, and educator. His main research activities include cooling, drying, and refrigeration pro-cesses

and systems, quality and safety of food products, bioprocess simulation and

optimization, and computer vision/image processing and hyperspectral imaging

technologies. His many scholarly works have become standard reference materi-als

for researchers, especially in the areas of computer vision, computational fluid

dynamics modeling, vacuum cooling, and related subjects. Results of his work have

been published in over 800 papers including more than 400 peer-reviewed journal

papers (Web of Science h-index = 79); among them, 31 papers have been selected

by Thomson Reuters’s Essential Science IndicatorsSM as highly cited papers, rank-

ing him no. 1 in the world in agricultural sciences (December 2015). He has also

edited 14 authoritative books. According to Thomson Scientific’s Essential Science

IndicatorsSM, based on data derived over a period of ten years from Web of Science,

there are about 4,500 scientists who are among the top one percent of the most cited

scientists in the category of Agriculture Sciences, and in the last few years, Professor

Sun has consistently been ranked among the very top 10 scientists in the world (he

was at the 9th position in January 2017), and has been named Highly Cited

Researcher in 2015 and 2016 by Thomson Reuters. He received a first-class BSc honors and MSc in mechanical engineering and a PhD

in chemical engineering in China before working in various universities in Europe. He

became the first Chinese national to be permanently employed in an Irish university when

he was appointed college lecturer at the National University of Ireland, Dublin

(University College Dublin, UCD), in 1995, and was then progres-sively promoted in the

shortest possible time to senior lecturer, associate professor, and full professor. Dr. Sun

is now a professor of food and biosystems engineering

xi

xii Series Editor

and the director of the UCD Food Refrigeration and Computerized Food Technology

Research Group. As a leading educator in food engineering, Prof. Sun has trained many PhD stu-dents

who have made their own contributions to the industry and academia. He has also

frequently delivered lectures on advances in food engineering at academic insti-tutions

worldwide, and delivered keynote speeches at international conferences. As a recognized

authority in food engineering, he has been conferred adjunct/visiting/­ consulting

professorships from 10 top universities in China, including Zhejiang University,

Shanghai Jiaotong University, Harbin Institute of Technology, China Agricultural

University, South China University of Technology, and Jiangnan University. In

recognition of his significant contribution to food engineering world-wide and for his

outstanding leadership in the field, the International Commission of Agricultural and

Biosystems Engineering (CIGR) awarded him the “CIGR Merit Award” in 2000, and

again in 2006, and the Institution of Mechanical Engineers based in the United Kingdom

named him “Food Engineer of the Year 2004.” In 2008, he was awarded the “CIGR

Recognition Award” in honor of his distinguished achievements as one of the top 1%

among agricultural engineering scientists in the world. In 2007, he was presented with

the only “AFST(I) Fellow Award” given in that year by the Association of Food Scientists

and Technologists (India), and in 2010, he was presented with the “CIGR Fellow Award”;

the title of Fellow is the highest honor at CIGR and is conferred to individuals who have

made sustained, outstanding con-tributions worldwide. In March 2013, he was presented

with the “You Bring Charm to the World Award” by Hong Kong–based Phoenix Satellite

Television with other award recipients including the 2012 Nobel Laureate in Literature,

and the Chinese Astronaut Team for Shenzhou IX Spaceship. In July 2013, he received

the “Frozen Food Foundation Freezing Research Award” from the International

Association for Food Protection (IAFP) for his significant contributions to enhancing the

field of food-freezing technologies. This is the first time that this prestigious award was

presented to a scientist outside the United States. In June 2015 he was presented with the

“IAEF Lifetime Achievement Award.” This IAEF (International Association of

Engineering and Food) award highlights the lifetime contribution of a prominent engineer

in the field of food.

Editors

Dr. Milan Houska, born June 16, 1952 in Prague.

1971–1976: MSc degree in process engineering and design of chemical and

food machinery 1980: PhD degree, thesis “Engineering Rheology of Thixotropic Fluids” 1980–1985: Scientific worker of Department of Physical Properties of Foods

at Food Research Institute Prague (FRIP) 1985–1998: Head of Department of Physical Backgrounds of Food Processing,

FRIP 1999–2015: Head of Department of Food Engineering, FRIP 2015–2017: Senior researcher June 2017–now: Vice-director for research at FRIP

He earned his PhD degree after 3 years of studying at Department of Process

Engineering at Faculty of Mechanical Engineering of the Czech Technical University

in Prague. The title of the PhD thesis was “Engineering Rheology of Thixotropic

Fluids.” After finishing PhD studies, he started to work at FRIP at the Department of

Physical Properties of Foods, where studies of texture and mechanical and ther-mal

properties were conducted. After several years of the work in this department, he

became a head of this department. After joining with the Department of Heat

Processing of Foods, he started to be a leader of the joint departments with the title

Department of Food Engineering.

Research activities • Rheological and mechanical properties of foods • Food properties database • Modelling of thermal processes during production • Distribution and retail and quantitative analysis of risk of growth and sur-

vival of pathogenic and spoilage microorganisms • Food color (with coworkers) • Influence of high pressure on foods • Vacuum cooling of liquid and solid foods • Enhanced speed thawing of foods

Main projects • Coordinator of the project “Aseptic cooker AV-630.” • Coworker at the project “Aseptic filling machine ASP200/360.” • Coordinator of the previous project granted by the National Agency for

Agricultural. • Research “Development of equipment and research of influence of high

pressure on nonthermal processing of foods,” successfully finished in 1998.

xiii

xiv Editors

• Coordinator of the project dealing with processing of foods that decrease

the allergenic activities of apple, carrot, and celery juices. • Coordinator of the project dealing with physical methods of treatment of

wine grapes to contain more resveratrol content (UV treatment, ozonized

water treatment, and storage). • He is an active editor of the Journal of Food Engineering, Elsevier.

Dr. Filipa Vinagre Marques da Silva’s research activity and interests are in Food

Process Engineering, in particular studying the effects of new food pres-ervation

technologies such as high-pressure processing, on food safety and shelf-life, and the

design of proper pasteurization processes. Her expertise in microbiology and

enzymes are helpful for studying the effect of emerging food pasteurization

technologies on food spoilage microbes/enzymes. The production of plant extracts

and the determination of their biological activity such as anti-bacterial, antifungal,

and insecticidal activities, is another area of research.

Contributors

Francisco Purroy Balda Pui Yee Lee Hiperbaric, S.A. Department of Food Science Burgos, Spain University of Otago

Dunedin, New Zealand Roman Buckow CSIRO Agriculture and Food Ariette Matser Werribee, Victoria, Australia Wageningen UR Food & Biobased

Research Begoña De Ancos Wageningen, the Netherlands Institute of Food Science, Technology

and Nutrition—ICTAN Indrawati Oey Spanish National Research Department of Food Science

Council—CSIC University of Otago Madrid, Spain Dunedin, New Zealand

Jaroslav Dobiáš Petr Pravda Department of Food Preservation Kofola Joint Stock Company University of Chemistry and Ostrava-Poruba, Czech Republic

Technology Prague, Czech Republic Concepci n Sánchez-Moreno

Institute of Food Science, Technology Evelyn and Nutrition—ICTAN Department of Chemical Engineering Spanish National Research University of Riau Council—CSIC Pekanbaru, Indonesia Madrid, Spain

Milan Houska Filipa Vinagre Marques da Silva Food Research Institute Chemical and Materials Engineering Prague, Czech Republic Department

University of Auckland Tatiana Koutchma Auckland, New Zealand Agriculture and Agri-Food Canada Guelph, Ontario, Canada

xv

xvi Contributors

Netsanet Shiferaw Terefe Martijntje Vollebregt

CSIRO Agriculture and Food Wageningen UR Food & Biobased

Werribee, Victoria, Australia Research

Jan Tříska

Wageningen, the Netherlands

Keith Warriner

Global Change Research Institute CAS

Brno, Czech Republic University of Guelph

Guelph, Ontario, Canada

Lukáš Vápenka

Department of Food Preservation

University of Chemistry and Technology

Prague, Czech Republic

2 High-Pressure

Processing Effect on

Microorganisms in Fruit

and Vegetable Products

Filipa Vinagre Marques da Silva and Evelyn

CONTENTS 2.1 Introduction....................................................................................................... 4

2.2 Spoilage Microorganisms in Fruit and Vegetable Products.............................. 4

2.2.1 Microbial Spores................................................................................... 4

2.2.2 Undesirable Microorganisms in Fruit Products.................................... 5

2.2.3 Undesirable Microorganisms in Vegetable Products............................ 6

2.3 Pasteurization.................................................................................................... 7

2.3.1 HPP Background................................................................................... 7

2.3.2 Mechanisms of Microbial Inactivation during HPP and HPTP........... 7

2.3.3 Models for Describing Log Microbial Survivors after HPP and HPTP.... 8

2.3.3.1 Simple First-Order Linear Model........................................... 9

2.3.3.2 Nonlinear Weibull Model..................................................... 10

2.4 HPP and HPTP Inactivation of Microorganisms in Fruit Products................ 11

2.4.1 Spore-Formers..................................................................................... 11

2.4.1.1 Bacterial Spores.................................................................... 11

2.4.1.2 Mold and Yeast Spores......................................................... 13

2.4.1.3 Modeling the Microbial Spore Inactivation......................... 13

2.4.2 Vegetative Cells................................................................................... 18

2.4.2.1 Log Reductions..................................................................... 18

2.4.2.2 Modeling the Microbial Inactivation.................................... 18

2.5 HPP and HPP-Thermal Inactivation of Microorganisms in Vegetable

Products........................................................................................................... 23

2.5.1 Spore-Formers..................................................................................... 23

2.5.2 Vegetative Cells................................................................................... 23

2.5.3 Modeling the Microbial Inactivation.................................................. 27

2.6 Design of HPP and HPTP Pasteurization Processes for Fruit

and Vegetable Products................................................................................... 27

2.6.1 HPP or HPTP Pasteurization Requirements for New Foods.............. 27

2.6.2 Fruit Products............................................................................. ......... 29

2.6.3 Vegetable Products and Low-Acid Foods........................................... 30

References ................................................................................................................ 31

3

4 High Pressure Processing of Fruit and Vegetable Products

2.1 INTRODUCTION High pressure processing (HPP), also named high hydrostatic pressure, is a modern

method of food pasteurization commercially used in many countries. It relies on the

application of very high pressures (up to 600 MPa) to the food/beverage to inactivate

microorganisms. Since no heat or mild heat is applied, most of the original food sensory,

nutrient, and functional properties are retained after processing, and fresh-like fruit and

vegetable products with longer shelf life are produced. HPP can damage the microbial

cell membrane, which affects its permeability and ion exchange, and denature proteins

involved in microbial replication. Examples of commercial HPP processed fruit and veg-

etable products are citrus/fruit/vegetable juices, fruit jams, jellies and dressings, avocado

products and salsas, and vegetable products/meals. After pasteurization, the fruit and

vegetable products may contain microorganisms in lower concentrations. Therefore, they

are stored cold and distributed at temperatures below 7°C to avoid or retard undesir-able

microbial growth during storage. The low temperature also inhibits enzymatic or other

biochemical spoilage reactions. The microorganisms able to grow under refriger-ated

conditions, classified as psychrotrophs, are more critical for HPP fruit and vegetable

products. Nevertheless, since few studies on psychrotroph’s inactivation by HPP are

available, all types of microorganisms were reviewed. Those were bacteria, molds, and

yeasts, which can be found in fruit and vegetable products and included spore-formers,

non-spore-formers, pathogenic, and spoilage organisms. We are listing different catego-

ries of microorganisms covered in the chapter.

2.2 SPOILAGE MICROORGANISMS IN

FRUIT AND VEGETABLE PRODUCTS The highest incidence of rapid spoilage of processed foods is caused by bacteria,

followed by yeasts and molds (Sinell, 1980). Parasites (protozoa and worms), natural

toxins, viruses, and prions can also be a problem if industry uses contaminated raw

materials (FDA, 1992).

2.2.1 MICROBIAL SPOREs Before discussing microbial targets of pasteurization, we must recognize that the

spore is the most resistant microbial form. Spore is a highly resistant dehydrated form

of dormant cell produced under conditions of environmental stress and as a result of

“quorum sensing.” Molds (e.g., Neosartorya fischeri, Byssochlamys nivea), certain

yeasts (Saccharomyces cerevisiae), and bacteria (Alicyclobacillus acidoterrestris,

Bacillus coagulans, Bacillus subtilis) can produce spores, although yeast spores are

not as resistant as bacterial spores. Heat is the most efficient method for spore

inactivation and is presently the basis of a huge world-wide industry (Bigelow and

Esty, 1920; Gould, 2006). Microbial spores are much more resistant to heat in

comparison to their vegetative counterparts, generally being able to survive the

pasteurization process. Similarly, spores are much more resistant to HPP than

vegetative cells, and usually HPP by itself is insufficient to inactivate spores in foods.

Thus, the combination of HPP with moderate heat

HPP Effect on Microorganisms in Fruit and Vegetable Products 5

(HPP-thermal or high pressure thermal processing—HPTP) is used to inactivate

spores. The HPTP requires lower temperatures and/or times than thermal pro-cessing

alone for the same spore inactivation (Evelyn and Silva, 2015a,b, 2016a,b; Evelyn et

al., 2016; Silva et al., 2012). Spore resistance may also be affected by the food

environment in which the organism is processed (Evelyn, 2016; Evelyn and Silva,

2015a, 2016b). For instance, spores (and vegetative cells) become more resistant at

low water activity (Corry, 1976; Murrel et al., 1966; Silva et al., 1999; Uchida and

Silva, 2017). The spore age is another important factor for spore resis-tance,

especially for mold spores, which become more resistant to HPTP with time (Evelyn

and Silva, 2017). If, after pasteurization, the storage temperature as well as the food

characteristics (pH, water activity, food constituents) are favor-able for sufficient

time, surviving spores can germinate and grow to attain high numbers (e.g., 107/g or

mL) and cause food-borne diseases or spoilage. Control of spores during storage of

pasteurized foods requires an understanding of both their resistance and outgrowth

characteristics.

2.2.2 UNDEsIRABLE MICROORGANIsms IN FRuIT PRODuCTs In high-acid and acidified foods, the main pasteurization goal is to avoid spoil-age

during distribution at room temperature or at refrigerated conditions, rather than

avoiding outbreaks of public health concern. High-acid foods include most of the

fruits, normally containing high levels of organic acids. The spoilage flora is mainly

dependent on pH and soluble solids. The type of organic acids and other constituents

of these foods such as polyphenols might also affect the potential spoilage

microorganisms. Given the high acid content of this class of foods (pH < 4.6), the

bacterial pathogens (vegetative and spore cells) including the deadly spore-forming

Clostridium botulinum are not able to grow. It is generally assumed that the higher

the acidity of the food, the less probable the germination and growth of bacterial

spores, a pH < 4.6 being accepted as safe in terms of patho-genic spore-formers.

However, various incidents in high-acid foods involving the spore-forming spoilage

bacterium Alicyclobacillus acidoterrestris (Cerny et al., 1984; Jay, 2000) have been

registered since its optimum growth pH is between 3.5 and 4.5 for the type strain

(Pinhatti et al., 1997), and optimum growth temperature is between 35°C and 53°C

(Deinhard et al., 1987; Sinigaglia et al., 2003) depend-ing on the strain.

Typical microbes associated with spoilage of high-acid and acidified foods are A.

acidoterrestris bacteria, molds such as Byssochlamys nivea and Neosartorya fischeri,

yeasts (e.g., Saccharomyces cerevisiae), and lactic acid bacteria (LAB; e.g.,

Lactobacillus, Leuconostoc). The growth of spoilage spore-forming Bacillus and

Clostridium has been reported in less acidic fruit products (3.7 < pH < 4.6) such as tomato

purée/juice, mango pulp/nectar, canned pear, and pear juice (Ikeyami et al., 1970;

Shridhar and Shankhapal, 1986). In addition, less resistant vegetative microor-ganisms

belonging to the LAB family that do not have the capacity to produce spores can be found

in spoiled fruits and vegetables. The Escherichia coli O157:H7 is a veg-etative pathogen

able to survive and grow at 25°C in acidic environments but not at ≤10°C (Conner et al.,

1995). It is known that Salmonella and E. coli 0157:H7 possess

6 High Pressure Processing of Fruit and Vegetable Products

relatively high resistance to acidic environments, being able to survive up to several

weeks at pH ≤ 4.6. Although growth is not probable in this acidic environment, their

very low infectious dose (10–100 cells) can become a public health concern even in

the absence of growth (FDA, 2011).

2.2.3 UNDEsIRABLE MICROORGANIsms IN VEGETABLE PRODuCTs Most of the bacteria grow best around pH values of 6.5 to 7. As opposed to high acid

fruit products, vegetable products and certain fruit juices (e.g., tomato, pear, some

tropical juices) have low acidity (pH > 4.6), and therefore vegetative bacte-rial

pathogens (e.g., Salmonella, Escherichia coli), bacterial spores from pathogens

(Clostridium botulinum, Bacillus cereus), and bacterial spores from spoilage species

(Geobacillus stearothermophilus = Bacillus stearothermophilus) can grow. With

respect to temperature, the optimum growth temperature of most bacteria is around

37°C. Thus, cold storage and distribution of low acidity vegetable products is an

additional hurdle to controlling the growth of possible survivors (e.g., spore-formers)

in the HPP pasteurized vegetable product. As mentioned, various pathogens can be associated with food-borne diseases and

outbreaks from improperly processed/preserved/stored low-acid chilled foods. With

respect to public health, the most dangerous spore-formers in low-acid chilled foods

are the psychrotrophic nonproteolytic strains of Clostridium botulinum (Gould, 1999;

Carlin et al., 2000a). In spite of the low incidence of this intoxi-cation, the mortality

rate is high if not treated immediately and properly. These strains of C. botulinum

have been implicated in human botulism incidents from the ingestion of not only a

few contaminated fish and meat products but also vegetable products (Lindström et

al., 2006) such as canned truffle cream/canned asparagus (Therre, 1999), pasteurized

vegetables in oil (Aureli et al., 1999), and canned egg-plant (Peredkov, 2004).

Bacillus cereus is another spore-forming and pathogenic bacterium detected in

pasteurized and chilled foods such as cooked rice and other chilled foods containing

vegetables (Carlin et al., 2000a,b), since some strains of B. cereus can grow at low

temperatures (T < 8°C) (Dufrenne et al., 1994, 1995; García-Armesto and

Sutherland, 1997; Choma et al., 2000). There are some non-pathogenic spore-

formers including Bacillus and Clostridium spp. (Broda et al., 2000), and molds that

can cause significant economic losses to food producers. For example, B. circulans

was identified as the major spoilage Bacillus in commercial vegetable purées

pasteurized and stored at 4°C (Carlin et al., 2000b). Very limited data on spoilage

and HPP/HPTP/thermal resistance of spore-formers are available in the literature. Other examples of foodborne infections from raw and processed foods include E.

coli serotype O157:H7 (verotoxigenic E. coli VTEC; raw fruit juice, lettuce) and

Vibrio cholerae (water, ice) (FDA, 1992; WHO, 2002). Psychrotrophic spoil-age

microbes such as LAB (Lactobacillus spp., Leuconostoc spp., Carnobacterium spp.),

molds (Thamnidium spp., Penicillium spp.), and yeasts (Zygosaccharomyces spp.)

can also occur in chilled low-acid vegetable products during storage in general due

to postprocess contamination. These are very sensitive to HPP.

HPP Effect on Microorganisms in Fruit and Vegetable Products 7

2.3 PASTEURIZATION Pasteurization was redefined by the United States Department of Agriculture as “any

process, treatment, or combination thereof, that is applied to food to reduce the most

resistant microorganism(s) of public health significance to a level that is not likely to

present a public health risk under normal conditions of distribution and storage”

(NACMCF, 2006). This definition therefore includes nonthermal pasteurization pro-

cesses such as HPPs, and the effects of HPP on microorganisms and foods are active

research topics (Karwe et al., 2014; Norton and Sun, 2008; Rendueles et al., 2011). The

efficacy of HPP in terms of microbial spore and endogenous enzyme inactiva-tion in fruit

and vegetable products is limited (Evelyn, 2016; Sulaiman and Silva, 2013; Sulaiman et

al., 2015, 2017; Van Buggenhout et al., 2006). Thus, simultaneous­ HPP-thermal (HPTP)

processing has been investigated for efficient spore inacti-vation (Evelyn and Silva,

2015a,b, 2016a; Evelyn et al., 2016). Silva et al. (2012) could successfully reduce the

temperature required to inactivate Alicyclobacillus acidoterrestris in orange juice from

85–95°C to 45–65°C when using 600 MPa HPP. Likewise, approximately less than 30°C

of temperature resulted in similar N. fischeri and B. nivea ascospore inactivation after 600

MPa HPTP of juice/puree (Evelyn and Silva, 2015b; Evelyn et al., 2016), thus

demonstrating the benefit of HPP technology.

2.3.1 HPP BACKGROuND HPP pasteurized foods were first seen in Japan from the early 1990s (Van Loey et

al., 2003), although the extension of food shelf life by HPP was known since 1899

(Hite, 1899). Fruit jams and sauces are examples of the first HPP processed foods,

followed by other food products such as guacamole in the United States, fruit juice

in France, Mexico, and the UK, and a delicatessen style ham in Spain (Patterson et

al., 2006). Since then, HPP has been extended to preserve fruits and vegetables

(32%), juices and beverages (11%), meat products (27%), seafood and fish (16%),

and other products (14%) (Buckow and Bull, 2012). Approximately 265 industrial-

scale HPP machines have been produced and installed worldwide for food process-

ing until 2014 with the highest number installed in the North America and Europe

(Hiperbaric, 2015). Please consult Chapter 5 for more details.

2.3.2 MEChANIsms Of MICROBIAL INACTIvATION DuRING HPP AND HPTP The mechanism of microbial inactivation by high pressure has been thoroughly

investigated. Considerable alterations in the cellular structure or physiological func-tions

of microorganisms after exposure to high pressure alone and combined with mild heat

result in microbial cell death. This can be seen by observing the structural damage of the

cell membrane and envelopes due to membrane phase transition and flluidity changes

(Abe, 2013; Rozali, 2015). However, microbial spores are distin-guishable from

vegetative cells in the mechanism of inactivation by high pressure. Generally, a two-step

inactivation process has been widely accepted for spore inac-tivation: (i) activation of

nutrient germinant receptors and the release of dipicolinic

8 High Pressure Processing of Fruit and Vegetable Products

Nonnutrient spore germination

Dominant at 100−200 MPa—

retarded up to 600 MPa, T:

30−50°C

Germinant receptors

(GerA homologs)

Nonphysiological germination

p > 600 MPa and T > 60°C

Nonphysiological germination

Retarded at 200 MPa—

dominant at 400−600 MPa, T

< 60°C

Release of ions and

Ca2+

−DPA (SpoVA protein unfolding?

irreversible or reversible changes in the inner membrane?)

Partial core hydration

Retarded at 400−600 MPa

and T < 50°C (Gpr inactivation?)

Cortex hydrolysis Rapid inactivation

and full core hydration > 7 log10

Active Gpr

SASP degradation

Max 4 log10 Inactivation

(pressure resistant

superdormant spores?)

FIGURE 2.1 Proposed germination and inactivation pathways of Bacillus subtilis, depen-

dent on the applied pressure (P) and temperature (T) conditions by Reineke et al. (2013)

(permission from Elsevier).

acid during germination, causing a loss of spore resistance; and (ii) subsequent inac-

tivation by pressure and heat (Black et al., 2005; Georget et al., 2015; Heinz and

Knorr, 2002; Mathys et al., 2009; Reineke et al., 2013). Reineke et al. (2013) suggested that spore germination and inactivation pathways were

dependent on the pressure–temperature combinations to explain the mecha-nism of

Bacillus subtilis spore inactivation by HPTP in buffer solution (Figure 2.1). For 100–200

MPa at 30–50°C, physiological spore germination occurs by trigger-ing germinant

receptors. Spores are able to degrade small acid-soluble proteins, but only 4 log

inactivation was obtained after long pressure dwell times (>1 h). For 400–600 MPa at T

< 60°C, and pressure (P) > 600 MPa and temperature (T) > 60°C, nonphysiological

pressure induced germination occurs followed by subsequent inac-tivation, which is

fastest and higher (>7 log inactivation). Nonetheless, more research is needed to elucidate

the mechanisms of the spore inactivation in food products.

2.3.3 MODELs fOR DEsCRIBING LOG MICROBIAL SuRvIvORs AfTER HPP AND HPTP

Mathematical models and kinetic parameters for microbial inactivation are impor-

tant tools to analyze the effectiveness of HPP and HPTP, to design new processes,

HPP Effect on Microorganisms in Fruit and Vegetable Products 9

Log

N/N

0

0 B. nivea inactivation in strawberry puree

(8.1°Brix) by 600 MPa–75°C

−1 A. acidoterrestris inactivation in apple

juice (10°Brix) by 600 MPa–45°C

−2

N. fischeri inactivation in apple juice

(10.6°Brix) by 600 MPa–75°C

S. cerevisiae inactivation in beer (4.8%

−3 alc/vol) by 400 MPa–room temperature

A. acidoterrestris inactivation in orange

−4

juice (9.2°Brix) by 600 MPa–65°C

−5

−6

0 10 20 30 40 50

Time (min)

FIGURE 2.2 Bacteria, mold and yeast spore inactivation by HPP and HPTP in fruit prod-

ucts and beer.

and to optimize food safety and quality. These are based on the reduction in the number

of microorganisms in response to the application of a lethal effect. Linear and nonlinear

models have been commonly used to describe the log survival curves of pathogenic and

spoilage bacteria after HPP and HPTP treatments. The nonlin-earity of log microbes vs.

time is very common, with curves presenting concave upward and tails as shown in

examples presented in Figure 2.2 for B. nivea, N. fisch-eri, S. cerevisiae, and A.

acidoterrestris spores submitted to HPP/HPTP. Note that although linearity was

registered for A. acidoterrestis spores in apple juice treated at 600 MPa–45°C, the

inactivation of spores suspended in orange juice treated at 600 MPa–65°C seemed

nonlinear, showing that the same microbe can exhibit linear or nonlinear behavior

depending on the processing conditions. The effect of pressure on microbial inactivation

is well known and similar to temperature. The higher the HPP pressure, the higher the

inactivation. Therefore, the HPTP inactivation studies are often conducted at the

maximum pressure allowed by the equipment with mea-surable changes in the microbial

concentration with processing time. 2.3.3.1 Simple First-Order Linear Model Predictive microbiology began when Bigelow and Esty (1920), Bigelow (1921), and Esty

and Meyer (1922) proposed the use of first-order kinetics to model the thermal

inactivation of microorganisms in foods. The model describes a linear decrease in the

logarithmic cell populations with time, as a constant intensity of pressure and/ or heat is

applied. The decimal reduction time DP,T value is the time in minutes at a

10 High Pressure Processing of Fruit and Vegetable Products

certain temperature and pressure necessary to reduce microbial population by 90%,

and is calculated from the reciprocal of the slope of the following equation:

log N −

t (2.1)

N 0

D

P ,T

The temperature coeffiicient zT value (°C) is the temperature increase for constant

pressure that results in a 10-fold decrease in the D value. This is estimated from the

negative reciprocal of the slope of Equation 2.2:

D

Tref − T

log

(2.2) D z

Tref T

DTref is the D value at the reference temperature Tref (can be any reference tem-

perature, °C); T is the temperature of the isothermal treatment (°C). Similarly, the pressure coefficient zP value (MPa) can also be estimated for a fixed temperature (Equation 2.3, P = HPP pressure in MPa):

D

Pref − P

log

(2.3) D z

Pr ef P

With respect to HPP, deviations from the linearity (e.g., tails) can be observed in the

survival curves (Evelyn and Silva, 2015a,b, 2016a,b; Evelyn et al., 2016), which can

mean that individuals of a microbial population have different resistances. The biphasic model is a particular case of the first-order kinetics, where the spore

survival line presents two rates of microbial inactivation corresponding to two D

values. 2.3.3.2 Nonlinear Weibull Model Due to its simplicity and accuracy, the Weibull distribution (Weibull, 1951) has been

used to describe the nonlinear microbial inactivation in various foods. Two math-

ematical forms of the Weibull model are shown in Equations 2.4 and 2.5. In the

Weibull adapted by Peleg and Cole (1998), b (the scale factor) is a rate parameter

that is related to the velocity of the inactivation of the microorganism, and n is the

survival curve shape factor:

log N −btn (2.4)

N

0

n < 1 and n > 1 correspond to survival curves with concave upward (tailings) and

concave downward (shoulders), respectively. If n = 1 t, the Weibull model becomes

the simple fiirst-order kinetics.

HPP Effect on Microorganisms in Fruit and Vegetable Products 11

Van Boekel (2002) presented another form of the Weibull model, in which the Greek

letters α and β are the scale and shape parameters, respectively (Equation 2.5). Likewise,

the survival curve is concave upward if β < 1 and concave downward if β > 1 and linear if β = 1:

log N

− 1 t β

(2.5)

N0

2.303 α

2.4 HPP AND HPTP INACTIVATION OF

MICROORGANISMS IN FRUIT PRODUCTS 2.4.1 SPORE-FORmERs In this section, a review of the inactivation results obtained with bacterial and mold

spores treated by HPTP and yeast spores treated by HPP in fruit products will be first

discussed followed by a review of the models and estimated parameters used to

predict microbial spore inactivation by HPP and HPTP in fruit products. Overall, the

spores of some strains of B. nivea mold appear to be more resistant to HPTP than N.

fischeri mold spores and A. acidoterrestris bacterial spores. The last two seem to

have similar resistance. The examples of spore survival lines shown in Figure 2.2

can also confirm this. 2.4.1.1 Bacterial Spores Table 2.1 shows the log reduction achieved in A. acidoterrestris and Bacillus coagu-lans

bacterial spores suspended in fruit juices, pulps, and concentrates after high pressure in

the range of 200 to 621 MPa combined with moderate temperatures of 45–90°C. Tomato

juice was HPTP at higher temperature, 105°C. The log reductions for A. acidoterrestris

in fruit juice concentrates were minimal due to the high sugar protective effect against

pressure and heat. For example, regarding apple juice con-centrates processed for 10 min

at 621 MPa–90°C, there is no inactivation for 70°Brix as opposed to 5.0 decimal

reductions in 35°Brix (Lee et al., 2006). Similarly, in another study with another strain of

apple juice/concentrates (35.7°Brix), there is no effect of 200 MPa–50°C process for 10

min vs. 2.0 log reduction in 11.2°Brix juice. The processing temperature has an important

role in the spore inactivation. In general, higher reductions in spores were obtained at

higher HPP temperatures (60–105°C). For example, HPTP of apple juice containing

ATCC 49025 strain pro-cessed at 621 MPa–90°C–1 min resulted in 6.0 log reductions

(Lee et al., 2002), whereas 600 MPa–45°C–10 min only achieved 1.2 log reductions

(Uchida and Silva, 2017) in spite of higher processing time. The effect of strain is also

noticeable in Sokołowska et al.’s (2013) results and by comparing between the results of

different authors. Likewise, B. coagulans is very resistant requiring also the use of heat

for its inactivation in tomato juice/pulp. The use of 105°C resulted in 3.2 log reductions

after 0.5 min processing. In general, to achieve 6 log bacterial spore reduction, the

maximum pressure and temperature should be used in HPTP processing. To reduce the

processing times and increase throughput, higher temperature is recommended.

TABLE 2.1 Bacterial Spore Inactivation in Fruit Products after HPP Combined with Moderate Heat (HPTP) Soluble

Solids Pressure Temp. Time Log

Bacteria Strain Fruit Products pH (°Brix) (MPa) (°C) (min) Reduction Reference

Alicyclobacillus acidoterestrisa ATCC 49025, Apple juice 3.7 nr 621 90 1 6.0 Lee et al. 2002 NFPA1013

Alicyclobacillus acidoterestrisa NFPA1013, Apple juice conc. 3.9 17.5 621 90 5 5.8 Lee et al. 2006 NFPA1101 Apple juice conc. 3.9 35 621 90 10 5.0

Apple juice conc. 3.9 70 621 90 10 0.0

Alicyclobacillus acidoterestris NZRM 4098 Orange juice 3.8 9.2 600 65 10 2.6 Silva et al. 2012

Alicyclobacillus acidoterestris NZRM 4447 Apple juice 3.4 10.6 600 45 10 1.2 Uchida 2015 (ATCC 49025) Lime juice conc. 2.5 20.2 600 45 10 0.5

Blackcurrant 3.1 30.3 600 45 10 0.2

juice conc.

Alicyclobacillus acidoterestris TO-117/02 Apple juice 3.3 11.2 200 50 10 2.0 Sokolowska et al. 2013 Concentrate 3.3 23.6 200 50 10 1.2

Concentrate 3.2 35.7 200 50 10 0.0

Alicyclobacillus acidoterestris TO-29/4/02 Apple juice 3.3 11.2 200 50 10 2.6

Concentrate 3.3 23.6 200 50 10 1.4

Concentrate 3.2 35.7 200 50 10 0.5

Bacillus coagulans 185A Tomato juice 4.2 6.0 600 105 0.5 3.2 Daryaei and Balasubramaniam 2013

Bacillus coagulans ATCC 7050 Tomato pulp 4.3 4.0 600 60 10 5.0 Zimmermann et al. 2013 a Cocktail of strains. nr: not reported.

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HPP Effect on Microorganisms in Fruit and Vegetable Products 13

2.4.1.2 Mold and Yeast Spores Table 2.2 presents the HPTP inactivation of resistant mold spores in fruit prod-ucts.

Similar to bacteria, no inactivation of Byssochlamys nivea was observed in bilberry

jam 63°Brix after 700 MPa–70°C–15 min, and in juice concentrates with 41 and

50°Brix after 5 min at 689 MPa–60°C. B. nivea seemed to be the most resistant among

all the molds, with log reductions between 1.5 and 3.2 after 600 to 700 MPa combined

with 70–75°C for 15 min. Ferreira et al. (2009) could obtain 6 log reduction when

using 90°C HPP instead of 70°C for 15 min. The three strains of Byssochlamys fulva

were much less resistant than B. nivea and reduced by 2.8– 3.6 log after 600 MPa–10

min, without any heating. Neosartorya fischeri in apple juice presented 3.7 log

reductions after 600 MPa–75°C–15 min treatment; 600 MPa HPP at room

temperature for 15 min could only achieve 1.1 log reduction in Talaromyces

avellaneus. HPP temperatures ≤ 45°C combined with 350–500 MPa could achieve

higher reduction in Eurotium repens (4.2 log) and Penicillium expan-sum (6.0 log)

spores, indicating lower resistance of these mold species. With respect to yeast ascospores, they present lower resistance than bacterial and

mold spores, and only ambient HPP was used (Table 2.3). Zygosaccharomyces bailii

spores were reduced from 0.5 (grape juice) to 2 log (cranberry juice) depending on

the juice after 15 min at 300 MPa. At 500 MPa, 6 log reduction of Saccharomyces

cerevisiae in apple and orange juices was obtained after 0.4 to 1.1 min process

depending on the strain.

2.4.1.3 Modeling the Microbial Spore Inactivation Depending on the study, the spore inactivation in fruits was linear (=first order kinet-

ics) or nonlinear, exhibiting an upward concavity and tail (see Figure 2.2). A review

of the models and its parameters is presented in Table 2.4. The increase in spore

resistance with processing time can result in tails in the survival curves and pose a

problem to HPP processors, it being more difficult to inactivate the spores as process-

ing time increases. Therefore, the increase in processing time is not the best strategy

for increasing log reductions. Instead, increasing the HPTP pressure and/or tempera-

ture will be more effective. However, most of the commercial machines operate at a

maximum pressure of 600 MPa and maximum temperature of 25°C, although for

experimental purposes, Hiperbaric built in 2009 a unique piece of equipment that

enables the combination of pressure (630 MPa working pressure) and temperature

(5–90°C). The design of commercial HPP units must be improved to handle higher

processing pressures and/or temperatures. The log inactivation of A. acidoterrestris with processing time was modeled with the

first-order kinetics, although a slight concavity was observed in some of the sur- vival lines by Silva et al. (2012) and Uchida and Silva (2017). At 600 MPa, the D65°C

value in orange juice was 3.4 min and zT value = 34.4°C, and for apple juice with an

other strain the D45°C value = 8.6 min. The D600 MPa, 45°C value increased from 8.6 min

in 10.6°Brix apple juice to 20 min in 20°Brix lime juice concentrate and 46 min in 30°Brix blackcurrant juice concentrate. First-order kinetics parameters were also

determined for S. cerevisiae in juices, which were much easier to inactivate at ≤40°C

(D500 MPa value 0.07 to 0.45 min). With respect to spores of Bacillus coagulans, and

TABLE 2.2 Mold Spore (4–5 Weeks Old) Inactivation in Fruit Products after HPP Alone and Combined with Moderate Heat Soluble

Solids Pressure Temp. Time Log

Molds Strain Fruit Products pH (°Brix) (MPa) (°C) (min) Reduction Reference

Byssochlamys nivea nr Pineapple nectar 3.7 12 600 90 15 6.0 Ferreira et al. 2009

600 70 15 1.5

Pineapple juice 3.7 13 600 90 5 6.0

600 70 15 2.0

Byssochlamys nivea DSM 1824 Grape juice nr nr 700 70 15 3.2 Butz et al. 1996

Byssochlamys nivea JCM 12806 Strawberry puree 3.4 8.1 600 75 15 1.8 Evelyn et al. 2015b

(CBS 696.95)

Byssochlamys nivea nr Apple juice concentrate 3.8 41 689 60 5 0.0 Palou et al. 1998

Cranberry juice concentrate 2.6 50 689 60 5 0.0

Byssochlamys nivea DSM 1824 Bilberry jam nr 63 700 70 15 0.0 Butz et al. 1996

Byssochlamys nivea FRR 4421 Mango puree* 5.0 nr 600 Room T 10 0.0 Chapman et al. 2007

FRR 3798 Mango puree* 5.0 nr 600 Room T 10 0.1

FRR 2457 Mango puree* 5.0 nr 600 Room T 10 3.0

Neosartorya fischeri JCM 1740 Apple juice 3.7 10.6 600 75 15 3.7 Evelyn et al. 2016

Byssochlamys fulva FRR 3792 Mango puree* 5.0 nr 600 Room T 10 2.8 Chapman et al. 2007

FRR 2295 Mango puree* 5.0 nr 600 Room T 10 3.1

FRR 2785 Mango puree* 5.0 nr 600 Room T 10 3.6 Voldřich et al. 2004

Talaromyces avellaneus nr Apple juice 4.5 11 600 17 15 1.1

Eurotium repens DSMZ 62631 Apple juice 3.3 nr 500 45 15 4.2 Merkulow et al. 2000

Penicillium expansum DSMZ 1994 Apple juice 3.3 nr 350 40 15 6.0

(CECT 2279)

*Although mango is a fruit, given the high pH (>4.6), pathogen and spoilage bacteria (including sporeformers) may also grow and care must be taken. nr: not reported.

14

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TABLE 2.3 Yeast Spore Inactivation in Fruit Products after HPP* Soluble Pressure Log

Spores Strain Fruit Products pH Solids (°Brix) (MPa) Time (min) Reduction Reference

Zygosaccharomyces ATCC Grape juice 3.0 nr 300 15 0.5 Raso et al. 1998 bailii 36947

Orange juice 3.9 nr 300 15 1.5

Apple juice 4.1 nr 300 15 1.5

Pineapple juice 3.4 nr 300 15 1.5

Cranberry juice 3.5 nr 300 15 2.0

Saccharomyces YM-147 Orange juice 3.9 nr 500 1.1 6.0 Zook et al. 1999 cerevisiae

Apple juice 3.8 nr 500 0.9 6.0

Saccharomyces nr Orange juice 3.7 11 500 0.4 6.0 Parish 1998 cerevisiae

*HPP was conducted at room temperature, without heat. nr: not reported.

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15

TABLE 2.4 Modeling the Microbial Spore Inactivation in Fruit Products after HPP and HPTP Soluble

Solids Pressure Temp.

Spores Fruit Products pH (°Brix) Model (MPa) (°C) Model Parameters* Reference

Bacteria

Alicyclobacillus Orange juice 3.8 9.2 First order 600 65 D-value zT-value: 34.4°C Silva et al. 2012 acidoterestris (min): 3.4

NZRM 4098

Alicyclobacillus Apple juice 3.4 10.6 First order 600 45 D-value Uchida 2015 acidoterestris (min): 8.6

NZRM 4447 (ATCC Lime juice 2.5 20.2 600 45 19.9

49025) conc.

Blackcurrant 3.1 30.3 600 45 46.1

juice conc.

Bacillus coagulans 185A Tomato juice 4.2 nr Weibull 600 95 b = 1.93; n = 0.68 Daryaei and Balasubramaniam 2013

Bacillus coagulans ATCC Tomato pulp 4.3 4.0 Biphasic 600 60 D-value (min)a: (1) 1.6 Zimmermann et al. 2013

7050 (2) 6.2

Molds Byssochlamys nivea JCM Strawberry puree 3.4 8.1 Weibull 600 75 b = 0.29; n = 0.66 Evelyn and Silva 2015b 12806 (CBS 696.95)

Neosartorya fischeri JCM Apple juice 3.7 10.6 Weibull 600 75 b = 1.44; n = 0.35 Evelyn et al. 2016 1740 (ATCC 1020)

(Continued)

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TABLE 2.4 (CONTINUED) Modeling the Microbial Spore Inactivation in Fruit Products after HPP and HPTP Soluble

Solids Pressure Temp.

Spores Fruit Products pH (°Brix) Model (MPa) (°C) Model Parameters* Reference

Eurotium repens Apple juice 3.3 12.4 Biphasic 500 45 D-value (min)a: (1) 2.0 Merkulow et al. 2000

DSMZ 62631 (2) 9.0

Penicillium expansum Apple juice 3.3 12.4 Biphasic 350 40 D-value (min)a: (1)<1.0 Merkulow et al. 2000

DSMZ 1994 (CECT 2279) (2) no inactivation

Yeastsb

Saccharomyces cerevisiae Orange juice 3.9 nr First order 500 Room T D-value (min): 0.18 zP-value: Zook et al. 1999 YM-147 117 MPa Apple juice 3.8 nr First order 500 Room T 0.45 115 MPa

Saccharomyces cerevisiae Orange juice 3.7 11 First order 500 Room T D-value (min): 0.067 zP-value: Parish 1998 123 MPa *D- and z-values are the first-order kinetic parameters (Equations 2.1, 2.2, and 2.3); b and n are the Weibull scale and shape factors (Equation 2.4), respectively. nr: not reported. a The biphasic model assumes two rates of inactivation corresponding to two D-values. The D-values were calculated from the inactivation rates published.

b HPP of yeast ascospores was conducted at room temperature, without heat.

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18 High Pressure Processing of Fruit and Vegetable Products

molds B. nivea and N. fischeri, the nonlinearity with concave upward (n between 0.35

and 0.68) was best described by the Weibull model (Equation 2.4). One other option

for these sort of nonlinear survival curves is the first-order biphasic, which divides

the inactivation into two straight lines, corresponding to two different rates, the first

higher inactivation rate presenting a lower D value, followed by a more resistant

microbial population with a higher D value. The biphasic model was fitted to B.

coagulans (600 MPa–60°C, D values of 1.6 and 6.2 min), and molds Eurotium repens

(500 MPa–45°C, D values of 2 and 9 min) and P. expansum (350 MPa–40°C, D

values of <1.0 followed by no inactivation).

2.4.2 VEGETATIvE CELLs 2.4.2.1 Log Reductions Although it is known that Salmonella declines or does not grow in acidic environ-

ments (pH 3.5 to 4.4; Parish et al., 1997), HPP studies at 615 MPa for 2 min resulted

in 9 log reductions in apple, orange, and grapefruit juices (Teo et al., 2001). E. coli

has been implicated in outbreaks in fresh unprocessed strawberries and other unpas-

teurized fruit products, but was easily inactivated (>8 log reductions) after 5 min at

350, 450, and 650 MPa at <35°C (Hsu et al., 2014). This result demonstrates that E.

coli is not a problem in HPP processed products. Table 2.5 presents a review of some

of the results obtained for the HPP inactivation of vegetative microorganisms in fruit

products. As opposed to bacterial and mold spore-formers (Tables 2.1 and 2.2), 6 or

more log reductions were obtained in single strength juices after HPP and no

additional heat needed (≤40°C). Except for Voldřich et al. (2004) who obtained 6 log

after 600 MPa–5 min, most of the authors investigated pressures between 300 and

400 MPa, which required 2 to 12 min processing times. However, those times could

be hugely reduced if 600 MPa was used. For example, Parish (1998) worked with

orange juice and S. cerevisiae and while under 500 MPa, 0.1 min was required for 6

log reductions, at 350 MPa 38 times more time (=3.8 min) was needed. As expected,

42°Brix orange juice concentrate required longer process-ing times than 11.4°Brix

orange juice (Basak et al., 2002). There is not a clear distinction of the resistance to

HPP between acid lactic bacteria and vegetative cells of molds and yeasts.

2.4.2.2 Modeling the Microbial Inactivation Modeling studies carried out with vegetative cell inactivation in fruit products

revealed log linearity with HPP time and some authors estimated the first-order

kinetic parameters (Table 2.6). Once again, to be able to obtain survival data and

model the kinetics, low HPP pressures were used. For example, at 350 MPa, the D

value ranged between 0.5 and 2 min. While the D value for S. cerevisiae in orange

juice was 0.63 min at 350 MPa, it decreased to 0.017 min at 500 MPa. The D values at 600 MPa can be estimated from the zP value provided by the authors.

Those are very useful to estimate minimum processing conditions equivalent to 6D or 6

log reductions (see Section 2.5 focusing on the design of pasteurization processes). The

estimated D600 MPa value for Leuconostoc mesenteroides in orange

TABLE 2.5 Microbial Inactivation of Vegetative Cells in Fruit Products after HPP* Soluble

Solids Pressure Time Log

Vegetative Cells Strain Fruit Products pH (°Brix) (MPa) (min) Reduction Reference

Bacteria Leuconostoc ATCC 8293 Orange juice 3.7 11.4 350 12 6.0 Basak et al. 2002 mesenteroides

Orange juice conc. 3.5 42 400 36.6 6.0

Leuconostoc ATCC 8293 Mango juice 4.5 15 400 4.2 6.0 Hiremath and Ramaswamy mesenteroides 2012

Lactobacillus brevis nr Orange juice 3.8 11.6 350 4 6.0 Katsaros et al. 2010

Lactobacillus plantarum nr Orange juice 3.8 11.6 350 3 6.0 Katsaros et al. 2010

Molds Talaromyces avellaneus nr Apple juice 3.45 10.8 600 5 6.0 Voldřich et al. 2004

Yeasts Candida lipolytica LMM02.68 Apple pieces in acidified 3.0 12.1 400 10 >6.0 Vercammen et al. 2012 glucose solution 24.3 400 10 >6.0

Zygosaccharomyces bailii ATCC 2333 Mango juice 4.5 15 350 3.72 6.0 Hiremath and Ramaswamy 2012

Zygosaccharomyces bailii ATCC 36947 Juices of: pineapple, 3.0–4.1 nr 300 5 4.5–5.0 Raso et al. 1998 grape, apple, cranberry,

and orange

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TABLE 2.5 (CONTINUED) Microbial Inactivation of Vegetative Cells in Fruit Products after HPP* Soluble

Solids Pressure Time Log

Vegetative Cells Strain Fruit Products pH (°Brix) (MPa) (min) Reduction Reference

Pichia membranifaciens ATCC 2085 Mango juice 4.5 15 300 6 6.0 Hiremath and Ramaswamy 2012

Saccharomyces cerevisiae ATCC 38618 Orange juice 3.7 11.4 250 32.4 6.0 Basak et al. 2002 Orange juice conc. 3.5 42 400 141 6.0

Saccharomyces cerevisiae nr Orange juice 3.7 10.7 500 0.1 6.0 Parish 1998 350 3.8 6.0

Saccharomyces cerevisiae nr Orange juice nr 11 300 15 ≥6.0 Kuldiloke and Eshtiaghi 2008

Saccharomyces cerevisiae ATTC 2601, Apple sauce 3.7 13 300 2.64 6.0 Chauvin et al. 2006 ATTC 9763,

UCD 552, Apple sauce 3.6 20 300 3 6.0

Pasteur Reda

Apple sauce 3.6 30 300 4.62 6.0

Saccharomyces cerevisiae ATTC 2601, Blueberries 3.0 11.6 300 2.2 6.0 Chauvin et al. 2005 ATTC 9763,

UCD 552, Diced apples 3.2 12.6 300 2 6.0

Pasteur Reda *HPP was carried out at temperatures ≤ 40°C. nr: not reported a Cocktail of strains.

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TABLE 2.6 First-Order Kinetic Parameters for the Inactivation of Vegetative Microorganisms in Fruit Products after HPP* Soluble

Solids Pressure

Vegetative Cells Fruit Products pH (°Brix) (MPa) First-Order Kinetic Parameters Reference

D-value (min) zP-value (MPa) Bacteria

Leuconostoc mesenteroides Orange juice 3.7 11.4 350 2.0 137 Basak et al. 2002

ATCC 8293 Orange juice concentrate 3.5 42 400 6.1 251

Leuconostoc mesenteroides Mango juice 4.5 15 400 0.7 72 Hiremath and Ramaswamy 2012

ATCC 8293

Lactobacillus brevis Orange juice 3.8 11.6 350 0.67 105 Katsaros et al. 2010

Lactobacillus plantarum Orange juice 3.8 11.6 350 0.5 81

Yeasts Zygosaccharomyces bailii Mango juice 4.5 15 350 0.62 84 Hiremath and Ramaswamy 2012

ATCC 2333

Pichia membranifaciens Mango juice 4.5 15 300 1.0 84 Hiremath and Ramaswamy 2012

ATCC 2085

Saccharomyces cerevisiae Orange juice 3.7 11.4 250 5.4 135 Basak et al. 2002

ATCC 38618 Orange juice concentrate 3.5 42 400 23.5 287

Saccharomyces cerevisiae Orange juice 3.7 10.7 500 0.017 106 Parish 1998 350 0.63

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TABLE 2.6 (CONTINUED) First-Order Kinetic Parameters for the Inactivation of Vegetative Microorganisms in Fruit Products after HPP* Soluble

Solids Pressure

Vegetative Cells Fruit Products pH (°Brix) (MPa) First-Order Kinetic Parameters Reference

D-value (min) zP-value (MPa)

Saccharomyces cerevisiaea Apple sauce 3.7 13 300 0.44 nr Chauvin et al. 2006 ATTC 2601, ATTC 9763, Apple sauce 3.6 20 300 0.50

UCD 522, Pasteur Red

Apple sauce 3.6 30 300 0.77

Saccharomyces cerevisiaea Blueberries 3.0 11.6 300 0.37 nr Chauvin et al. 2005 ATTC 2601, ATTC 9763, Diced apples 3.2 12.6 300 0.33

UCD 522, Pasteur Red *DT and z-value are the first-order kinetic parameters (Equations 2.1 and 2.3); room temperature HPP with T ≤ 25°C. nr: not reported. a Cocktail of strains.

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HPP Effect on Microorganisms in Fruit and Vegetable Products 23

juice and orange juice concentrate is 2 and 58 s, respectively. D600 MPa values in orange

juice of Lactobacillus brevis is 0.12 s, and in Lactobacillus plantarum, it is 0.075 s.

2.5 HPP AND HPP-THERMAL INACTIVATION OF

MICROORGANISMS IN VEGETABLE PRODUCTS Most vegetable products present low acidity (pH > 4.6) and therefore microbial safety is

a concern. In practice, a cheaper and consumer acceptable solution is to combine

vegetable juices with fruit juices containing a high content of acids, causing pH lower-

ing (Houška et al., 2006). In this section, a review of studies carried out with spore and

vegetative microbial cells inactivation/modeling in vegetable products is presented.

2.5.1 SPORE-FORmERs Table 2.7 presents a review of the microbial spore inactivation in vegetable products after

HPTP and HPP. As opposed to fruit beverages (e.g., juices) and other fruit prod-ucts, not

many studies were carried out with vegetable products. Ananta et al. (2001) worked with

the very resistant Bacillus stearothermophilus, which was renamed Geobacillus

stearothermophilus. This is a thermophile (optimum growth 30–75°C) bacterium that

causes spoilage in food products. Being one of the most resistant spores, it is commonly

used as a challenge organism for validation of thermal sterilization processes. If G.

stearothermophilus is inactivated, all the other less resistant spore-formers will be as well.

HPTP at 600 MPa–90°C required very long times of 45 and 30 min for six decimal

reductions in the spores suspended in cocoa mass and mashed broccoli, respectively.

Increasing the HPTP temperature from 90°C to 95°C allowed the reduction of the time

from 30 to 12 min. Cold storage is still the best method to con-trol the growth of this

bacterium. Six log reductions with less resistant Bacillus species were obtained with

Bacillus licheniformis in carrot juice after 600 MPa–60°C– 4.2 min. Room temperature

HPP at 500 MPa for 20 min could only reduce B. subtilis by 3.2 log in cantaloupe juice,

confirming that HPTP is required for efficient bacterial spore inactivation. Merkulow et

al. (2000) investigated the inactivation of E. repens and P. expansum mold spores in

broccoli juice: while only 5 min at 350 MPa–40°C were needed for 6 log reductions of P.

expansum, a long time of 96 min at 500 MPa– 45°C was needed for E. repens. Similar to

bacteria, using higher HPTP temperatures (60–90°C) to achieve a quick inactivation of

mold spores in vegetable products is rec-ommended. As mentioned previously, the design

of commercial HPP units must be improved to handle higher processing pressures and/or

temperatures.

2.5.2 VEGETATIvE CELLs Table 2.8 presents a review of microbial inactivation of vegetative microorganisms in

vegetable products. The microorganisms investigated were the bacteria Escherichia coli

(including O157:H7), Salmonella typhimurium and Salmonella enterica, the Aspergillus

flavus mold, and S. cerevisiae yeast. Regarding processing conditions for E. coli

inactivation (6–6.4 log reductions) in carrot juice, the results can vary

TABLE 2.7 Microbial Spore Inactivation in Vegetable Products after HPP and HPTP Vegetable

Spores Products pH Pressure (MPa) Temp. (°C) Time (min) Log Reduction Reference

Bacteria Bacillus stearothermophilus* Cocoa mass nr 600 90 45 6.0 Ananta et al. 2001

ATCC 7953 (70%)

Bacillus stearothermophilus* Mashed broccoli nr 600 90 30 6.0 Ananta et al. 2001

ATCC 7953 95 12 6.0

Bacillus licheniformis Carrot juice 6.2 600 60 4.2 6.0 Tola and Ramaswamy 2014

Bacillus subtilis Cantaloupe juice 5.7 500 Room T 20 3.2 Ma et al. 2010

Molds

Eurotium repens Broccoli juice 6.6 500 45 96 6.0 Merkulow et al. 2000

DSMZ 62631

Penicillium expansum Broccoli juice 6.6 350 40 5 6.0 Merkulow et al. 2000

DSMZ 1994 *Renamed Geobacillus stearothermophilus. nr: not reported.

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TABLE 2.8 Microbial Inactivation of Vegetative Cells in Vegetable Products after HPP* Vegetative Cells Vegetable Products pH Pressure (MPa) Time (min) Log Reduction Reference

Bacteria

Escherichia coli O157:H7a Carrot juice 6.2 615 2 6.4 Teo et al. 2001 ATCC 43895, SEA 13B88, 932

Escherichia coli Carrot juice 6.6 600 15 6.0 Van Opstal et al. 2005

MG1655

Escherichia coli Cantaloupe juice 5.7 500 8 5.0 Ma et al. 2010

Escherichia coli Apple–broccoli juice 4.2 500 4 >6.0 Houška et al. 2006 acidified

Escherichia coli O157:H7 Alfalfa seeds nr 475 8 2.0 Ariefdjohan et al. 2004

MF7123A

Escherichia coli O157:H7a Green onions nr 450 2 2.2 Neetoo et al. 2011 250, cider strain, DD3795

Salmonella Carrot juice 6.2 615 2 5.1–7.8 Teo et al. 2001

5 strains

Salmonella typhimurium and entericaa Alfalfa seeds in water nr 600 25 5.0 Neetoo and Chen 2010 T43, T45, TDT 104, W35, Mo57

Salmonella typhimurium and entericaa Jalapeño pepper nr 500 2 3.5 Neetoo and Chen 2012 T43, T45, TDT 104, W35, Mo57 Serrano pepper 5.1

Salmonella entericaa Green onions nr 450 2 3.5 Neetoo et al. 2011 T43, T45, TDT 104

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TABLE 2.8 (CONTINUED) Microbial Inactivation of Vegetative Cells in Vegetable Products after HPP* Vegetative Cells Vegetable Products pH Pressure (MPa) Time (min) Log Reduction Reference

Molds

Aspergillus flavusa Apple–broccoli juice 4.2 400 5 >5.7 Houška et al. 2006 acidified

Yeasts

Saccharomyces cerevisiaea Apple–broccoli juice 4.2 400 5 >5.0 Houška et al. 2006 acidified

Saccharomyces cerevisiae Beetroot juice 4.2 300 10 3.5 Sokołowska et al. 2013

NCFB 3191 acidified a Cocktail of strains. *Room temperature HPP, T below 40°C. nr: not reported.

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HPP Effect on Microorganisms in Fruit and Vegetable Products 27

from 15 min at 600 MPa with strain MG1655 to 2 min at 615 MPa with a cocktail of

strains, thus emphasizing the importance of the strain for the resistance to the HPP

treatment. High log reductions were also obtained in acidified apple-broccoli (>6) and

cantaloupe (5.0) juices, while lower inactivation (2 decimal log) was obtained in alfalfa

seeds, probably due to low water content. With respect to Salmonella, except alfalfa

seeds, 2 min HPP with pressures ranging between 450 and 615 MPa could achieve 3.5

(green onion) to 7.8 (carrot juice) log reductions, depending on the vegetable product and

strain. Houška et al. (2006) showed >5.0 log reductions for A. flavus and S. cerevisiae in

apple-broccoli juice after 5 min at 400 MPa.

2.5.3 MODELING ThE MICROBIAL INACTIvATION Table 2.9 shows the modeling of microbial inactivation carried out in vegetable prod-

ucts. B. licheniformis spore inactivation in carrot juice and E. repens/P. expansum spore

inactivation in broccoli juice were nonlinear. The first was modeled with Weibull

distribution (Tola and Ramaswamy, 2014) and the second used a biphasic model. For E.

repens submitted to 500 MPa–45°C, initially the D value was 16 min, and after 125 min

a plateau without any inactivation was registered. Regarding P. expansum, first the D

value was <1 min followed by no inactivation (350 MPa– 40°C; Merkulow et al., 2000).

The inactivation of B. stearothermophilus spores in cocoa mass was nonlinear and

modeled with a more complex nth-order kinetics model (Ananta et al., 2001). Although

B. licheniformis inactivation was nonlinear for 400–500 MPa and 40–50°C, it was readily

inactivated at 600 MPa combined with the higher temperature tested of 60°C, and the

inactivation in this case was close to linear. Therefore, the first-order model was also used

successfully with a D value of 0.70 min for 600 MPa–60°C (Tola and Ramaswamy,

2014). The results demonstrated how important it is to use higher pressures and

temperatures to avoid nonlinearity and obtain a quick inactivation of the microorganisms.

The inactivation of the veg-etative microorganism E. coli in carrot juice did not require

heat and was log linear presenting a D value of 2.5 min at 600 MPa (Van Opstal et al.,

2005).

2.6 DESIGN OF HPP AND HPTP PASTEURIZATION

PROCESSES FOR FRUIT AND VEGETABLE PRODUCTS 2.6.1 HPP OR HPTP PAsTEuRIZATION REQuIREmENTs fOR NEW FOODs In general, a pasteurization process design for a new food product must meet its

specifications, such as: if the food will be distributed at room temperature or refrig-

erated, the shelf life, and the consumer types (infants, elderly, or the sick; Silva and

Gibbs, 2009). The following guidelines are recommended for developing a new food

pasteurization process (Silva and Gibbs, 2009; Silva et al., 2014):

(i) Conduct a hazard analysis to identify the microorganism(s) of public health

concern and spoilage in the fruit or vegetable product. Include spore-

formers able to germinate and grow in the food causing food degradation,

under the storage conditions (e.g., temperature, atmosphere).

TABLE 2.9 Modeling the Microbial Inactivation in Vegetable Products after HPP and HPTP* Vegetable Products Pressure Temp.

Form pH Model (MPa) (°C) Kinetic Parameters Reference Spores

Bacillus licheniformis Carrot juice 6.2 First order 600 60 D-value zP-value = 339 MPa Tola and Ramaswamy 2014 (min): 0.70

zT-value = 23.2°C Carrot juice 6.2 Weibull 600 60 α = 0.13; β = 0.70

Eurotium repens Broccoli 6.6 Biphasic 500 45 D-value (min): (1) 16.0 Merkulow et al. 2000 juice

DSMZ 62631 (2) no inactivation

Penicillium expansum Broccoli 6.6 Biphasic 350 40 D-value (min): (1) <1 Merkulow et al. 2000 juice

DSMZ 1994 (CECT 2279) (2) no inactivation

Vegetative Cells

Escherichia coli Carrot juice 6.6 First order 600 20 D-value (min): 2.5 Van Opstal et al. 2005

MG 1655 (ATCC 47076) *D- and z-values are the first-order kinetic parameters (Equations 2.1, 2.2, and 2.3); α and β are the scale and shape factors of the Weibull model (Equation 2.5),

respectively.

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HPP Effect on Microorganisms in Fruit and Vegetable Products 29

(ii) Always check for C. botulinum growth potential in the new food,

especially if a vegetable product is to be processed. (iii) Select the most resistant microorganism that is likely to survive the

process as a pasteurization target. (iv) Consider the level of inactivation needed (number of decimal log reduc-

tions). Ideally, this would involve determining the initial cell numbers and

normal variations in concentrations that occur prior to pasteurization. (v) Set a minimum P value (pasteurization value) that delivers at least 6 log

reductions in the most resistant microbe. The P value in HPP and HPTP

processes is the processing time during the constant pressure phase of the

HPP or HPTP cycle. (vi) Determine experimentally the selected microbe inactivation in the new food

for different processing conditions and assess the impact of the food matrix

on the microbial survival. (vii) Validate the efficacy of the pasteurization process by performing storage

tests under specific conditions (ambient or chilled storage). (viii) Define the critical limits needed during processing to meet the

performance standards. (ix) Define operating parameters (pressure and time for HPP and temperature

for HPTP) for the proposed HPP or HPTP pasteurization process. (x) Use preservatives for additional safety or longer shelf life.

Due to the wide variety and combinations of HPP/HPTP parameters, a process must

be defined for each type of food. The design process requires careful control of food

composition, including pH, water activity, or soluble solids content (°Brix), and

preservatives. The critical HPTP process parameters include the initial food tempera-ture,

the process pressure during the constant pressure phase, the process time during the

constant pressure phase, and the average temperature during the constant pressure phase.

Usually the times to reach the HPP pressure (less than 2 min) and to decompress (less

than 30 s) are not accounted for in the HPP pasteurization time. This procedure allows

more processing and to work on the safe side, as opposed to underprocessing. Other

factors such as the presence of added CO2 (e.g., carbonated beverages) require extra care,

especially during decompression to avoid package bursting.

2.6.2 FRuIT PRODuCTs A critical factor in high-acid and acidified foods is the pH. This factor should be

controlled before and after the pasteurization and during storage since the thermal

process and subsequent storage may increase the pH allowing growth of pathogens

and some resistant spore-forming Bacillus species. The pH of less acid fruits must

be controlled at least below 4.5 by acidification. Another concern refers to the endog-

enous heat-resistant enzymes from fruits. Those should be inactivated by pasteuri-

zation, since if they are active during storage, they can also modify the food pH

allowing food poisoning outbreaks and spoilage. In low pH (<4.6) high-acid foods, no Clostridium botulinum has been detected that

will germinate, grow, and produce toxin (Blocher and Busta, 1983). The majority

30 High Pressure Processing of Fruit and Vegetable Products

of bacterial spores would be inhibited by the low pH, and only acid-tolerant micro-

organisms such as Alicyclobacillus acidoterrestris, molds, yeasts, LAB, and acetic acid

bacteria might develop. The yeasts, lactic acid, and acetic acid bacteria of high-acid

products are less heat resistant than most of the bacterial and mold spores, and therefore

a milder HPP without heat is sufficient for their inactivation and subsequent storage. Silva

et al. (1999) proposed A. acidoterrestris spores as a reference target of thermal

pasteurization for shelf-stable high acidic fruit products (Silva and Gibbs, 2001, 2004).

Since the HPP fruit products are usually cold stored, A. acidoterrestris will not be able to

grow at low temperatures. Nevertheless, the review of resistance to HPTP processes of

bacterial spores presented in Table 2.1 showed that a cocktail of ATCC 49025 and NFPA

1013 A. acidoterrestris spores suspended in apple juice processed at 621 MPa at 90°C

for 1 min was reduced by 6 log (Lee et al., 2002), the minimum recommended for food

pasteurization. With respect to B. coagulans (ATCC 7050) suspended in tomato pulp,

five decimal reductions were registered after a 10 min HPTP process at 600 MPa–60°C

(Zimmermann et al., 2013). Mold spores are a great concern in fruit products since they can be very resis-tant

to pressure, as shown in the review of Table 2.2, and grow at lower tempera-tures

than the bacterial spores. In addition, they can germinate and grow under acidic

conditions of fruit products. Among the molds investigated, B. nivea is the most

resistant mold and can exhibit higher resistance than A. acidoterrestris bacte-rial

spores. The resistance and nonlinear properties of B. nivea can be different,

depending on the strain and spore age. Ferreira et al. (2009) was able to obtain 6 log

reductions in pineapple nectar and juice after HPTP at 600 MPa and 90°C for 15 and

5 min, respectively. The yeast ascospores are much less resistant than B. nivea, not

requiring heat for their inactivation. For example, Zook et al. (1999) obtained 6 log

reductions after 1.1 min room temperature HPP at 500 MPa. Lastly, if a pro-cess is

targeting only non-spore-forming bacteria, the HPP treatments to obtain 6D at 600

MPa will be very short: L. mesenteroides 12 s in orange juice and 348 s in 42°Brix

orange concentrate; L. brevis in orange juice 0.72 s; L. plantarum in orange juice

0.45 s. In conclusion, the major concerns are B. nivea and N. fisheri mold spores, if the

fruit products to be processed are prone to contamination by these fungi.

2.6.3 VEGETABLE PRODuCTs AND LOW-ACID FOODs Vegetable products belong to the low-acid foods (pH > 4.6) class. To minimize the out-

growth of pathogenic microbes in the foods during distribution, the microbial spores

surviving pasteurization must be controlled by using cold storage and transportation (1–

8°C), and a limited shelf-life. Vegetable products such as soup, some sauces, food

ingredients, and certain fruit juices (e.g., pear, some tropical juices) are examples of low-

acid foods. For this class of foods, food processors have to demonstrate that the processed

food is safe, not being capable of supporting the growth and toxin production by C.

botulinum within the specified storage life of the food. The follow-ing microbes are able

to grow at pH > 4.6 and at low temperatures: nonproteolytic C. botulinum, Listeria,

Yersinia enterocolitica, Aeromonas, Vibrio parahaemolyti-cus; a few strains of Bacillus

cereus, Escherichia coli O157:H7, Salmonella; the

HPP Effect on Microorganisms in Fruit and Vegetable Products 31

spoilage LAB, molds, and yeasts. Unfortunately, no study is available with C. botuli-num,

B. cereus, and other pathogenic microorganisms in vegetable products, although it is

known to be very difficult to inactivate psychrotrophic B. cereus spores in milk at 600

MPa–75°C (Evelyn and Silva, 2015a). The review presented in Table 2.7 for microbial

spores demonstrated that Bacillus stearothermophilus (=Geobacillus stearothermophilus)

spores are very resistant requiring ≥600 MPa combined with temperatures in the

magnitude of 90–95°C and quite long processing times of 12 to 45 min for six decimal

reductions (Ananta et al., 2001). The B. licheniformis spores are less resistant requiring

lower temperature and time (=600 MPa–60°C–4.2 min) for the same inactivation (Tola

and Ramaswamy, 2014). The survivors of mesophilic (optimum growth temperature 10–

50°C) and thermophilic (optimum growth tempera-ture 50–70°C) spores, including some

strains of Clostridium botulinum (Juneja and Marks, 1999) and B. cereus, C. perfringens,

B. coagulans, G. stearothermophilus, and Desulfotomaculum nigrificans, will not be able

to grow under refrigerated storage (T < 8°C). The distribution chain should be carefully monitored and checked for tempera-ture

abuses. E. repens mold spore was very difficult to inactivate (96 min) in broccoli juice using

HPP alone at 500 MPa, while P. expansum spores reached the six log reduc-tions after 5 min

at 350 MPa–40°C (Merkulow et al., 2000). From Table 2.8 with vegeta-tive microbial cells,

both cocktails of E. coli O157:H7 (three strains) and Salmonella (five strains) suspended in

carrot juice required only 2 min at 615 MPa at room temperature to achieve six or more log

reductions (Teo et al., 2001), while MG1655 E. coli required 15 min at 600 MPa for the same

inactivation (Van Opstal et al., 2005). Some of the mentioned processes are insufficient to achieve six decimal reduc-

tions of C. botulinum. Therefore, addition of preservatives is necessary for safety

assurance. The surviving Clostridium and Bacillus spores must be controlled with refrigeration (T < 8°C) and other hurdles such as salts (>3.5% salt-on-water, e.g.,

NaCl, sodium lactate) and nitrites (>100 ppm, e.g., NaNO2). It is known from the

literature that a salt content ≥3.5% in the food stops or retards the botulinum growth during chill storage (Graham et al., 1996; Peck, 2006).

REFERENCES Abe, F. 2013. Dynamic structural changes in microbial membranes in response to high

hydrostatic pressure analyzed using time-resolved fluorescence anisotropy measure-

ment. Biophysical Chemistry 183:3–8. Ananta, E., Heinz, V., Schlüter, O., and Knorr, D. 2001. Kinetic studies on high pressure inac-

tivation of Bacillus stearothermophilus spores suspended in food matrices. Innovative

Food Science & Emerging Technologies 2:261–272. Ariefdjohan, M.W., Nelson, P.E., Singh, R.K., Bhunia, A.K., Balasubramaniam, V.M., and

Singh, N. 2004. Efficacy of High Hydrostatic Pressure Treatment in Reducing

Escherichia coli O157 and Listeria monocytogenes in Alfalfa Seeds. Journal of Food

Science 64(5):M117–M120. Aureli, P., Fenicia, L., and Franciosa, G. 1999. Classic and emergent forms of botulism: The

current status in Italy. Eurosurveillance 4:7–9. Basak, S., Ramaswamy, H.S., and Piette, J.P.G. 2002. High pressure destruction kinetics of

Leuconostoc mesenteroides and Saccharomyces cerevisiae in single strength and con-

centrated orange juice. Innovative Food Science & Emerging Technologies 3:223–231.

32 High Pressure Processing of Fruit and Vegetable Products

Bigelow, W.D. 1921. The logarithmic nature of thermal death time curves. Journal of Infectious Diseases 29(5):528–536.

Bigelow, W.D., and Esty, J. 1920. The thermal death point in relation to time of typical ther-mophilic organisms. Journal of Infectious Diseases 27(6):602–617.

Black, E.P., Koziol-Dube, K., Guan, D., Wei, J., Setlow, B., Cortezzo, D.E., Hoover, D.G.,

and Setlow, P. 2005. Factors influencing germination of Bacillus subtilis spores via

activa-tion of nutrient receptors by high pressure. Applied and Environmental

Microbiology 71(10):5879–5887. Blocher, J.C., and Busta, F.F. 1983. Bacterial spore resistance to acid. Food Technology

37(11):87–99. Broda, D.M., Saul, D.J., Lawson, P.A., Bell, R.G., and Musgrave, D.R. 2000. Clostridium

gasigenes sp nov., a psychrophile causing spoilage of vacuum packed meat.

International Journal of Systematic and Evolutionary Microbiology 50(1):107–118. Buckow, R., and Bull, M. 2012. High pressure processing for seafood & meat products.

Retrieved­ November 11, 2015, from http://allnaturalfreshness.com/wp-content/uploads

/2013/08/HPP-MeatSeafood-Workshop-May2012.pdf. Butz, P., Funtenberger, S., Haberditzl, T., and Tauscher, B. 1996. High pressure inactivation

of Byssochlamys nivea ascospores and other heat resistant moulds. LWT—Food Science

and Technology 29(5–6):404–410. Carlin, F., Girardina, H., Peck, M.W., Stringer, S.C., Barker, G.C., Martinez, A., Fernandez, A.,

Fernandez, P., Waites, W.M., Movahedi, S., Van-Leusden, F., Nauta, M., Moezelaar, R., del-

Torre, M., and Litman, S. 2000a. Research on factors allowing a risk assessment of spore-

forming pathogenic bacteria in cooked chilled foods containing vegetables: FAIR

collaborative project. International Journal of Food Microbiology 60:117–135. Carlin, F., Guinebretiere, M.H., Choma, C., Pasqualini, R., Braconnier, A., and Nguyen, C.

2000b. Spore-forming bacteria in commercial cooked, pasteurised and chilled veg-etable

purees. Food Microbiology 17(2):153–165. Cerny, G., Hennlich, W., and Poralla, K. 1984. Fruchtsaftverderb durch bacillen: Isolierung und

charakterisierung des verderbserregers. Z. Lebensm. Unters. Forsch. 179(3):224–227. Chapman, B., Winley, E., Fong, A.S.W., Hocking, A.D., Stewart, C.M., and Buckle, K.A.

2007. Ascospore inactivation and germination by high pressure processing is affected

by ascospore age. Innovative Food Science & Emerging Technologies 8(4):531–534. Chauvin, M.A., Lee, S.Y., Chang, S., Gray, P.M., Kang, D.H., and Swanson, B.G. 2005. Ultra

high pressure inactivation of Saccharomyces cerevisiae and Listeria innocua on apples

and blueberries. Journal of Food Processing and Preservation 29(5–6):424–435. Chauvin, M.A., Chang, S., Kang, D.H., and Swanson, B.G. 2006. Sucrose and ultra high pres-

sure inactivation of Saccharomyces cerevisiae and Listeria innocua. Journal of Food

Processing and Preservation 30(6):732–741. Choma, C., Guinebretiere, M.H., Carlin, F., Schmitt, P., Velge, P., Granum, P.E., and Nguyen-

The C. 2000. Prevalence, characterization and growth of Bacillus cereus in commer-cial

cooked chilled foods containing vegetables. Journal of Applied Microbiology

88(4):617–625. Conner, D.E., and Kotrola, J.S. 1995. Growth and survival of Escherichia coli O157: H7 under

acidic conditions. Applied and Environmental Microbiology 61(1):382–385. Corry, J.E.L. 1976. The effects of sugars and polyols on the heat resistance and morphology

of osmophilic yeasts. Journal of Applied Bacteriology 40(3):269–276. Daryaei, H., and Balasubramaniam, V.M. 2013. Kinetics of Bacillus coagulans spore inactiva-tion

in tomato juice by combined pressure–heat treatment. Food Control 30(1):168–175. Deinhard, G., Blanz, P., Poralla, K., and Altan, E. 1987. Bacillus acidoterrestris sp. nov., a

new thermotolerant acidophile isolated from different soils. Systematic and Applied

Microbiology 10:47–53.

HPP Effect on Microorganisms in Fruit and Vegetable Products 33

Dufrenne, J., Soentoro, P., Tatini, S., Day, T., and Notermans, S. 1994. Characteristics of

Bacillus-cereus related to safe food-production. International Journal of Food

Microbiology 23(1):99–109. Dufrenne, J., Bijwaard, M., te-Giffel, M., Beumer, R., and Notermans, S. 1995. Characteristics

of some psychrotrophic Bacillus cereus isolates. International Journal of Food

Microbiology 27:175–183. Esty, J.R., and Meyer, K.F. 1922. The heat resistance of the spores of B. botulinus and allied

anaerobes. Journal of Infectious Diseases 31(6):650–663. Evelyn. 2016. Power ultrasound and high pressure processing inactivation of specific

microbial spores in foods. Doctoral Thesis, Department of Chemical and Materials

Engineering, University of Auckland, New Zealand. Evelyn, and Silva, F.V.M. 2015a. High pressure processing of milk: Modeling the inactivation

of Bacillus cereus spores at 38−70°C. Journal of Food Engineering 165:141–148. Evelyn, and Silva, F.V.M. 2015b. Inactivation of Byssochlamys nivea ascospores in straw-

berry puree by high pressure, power ultrasound and thermal processing. International

Journal of Food Microbiology 214:129–136. Evelyn, and Silva, F.V.M. 2016a. High pressure thermal processing for the inactivation of

Clostridium perfringens spores in beef slurry. Innovative Food Science & Emerging

Technologies 33:26–31. Evelyn, and Silva, F.V.M. 2016b. Modeling the inactivation of psychrotrophic Bacillus cereus

spores in beef slurry by 600 MPa HPP combined with 38–70°C: Comparing with

thermal processing and estimating the energy requirements. Food and Bioproducts

Processing 99, 179–187. Evelyn, Kim, H.J., and Silva, F.V.M. 2016. Modeling the inactivation of Neosartorya fischeri

ascospores in apple juice by high pressure, power ultrasound and thermal processing.

Food Control 59:530–537. Evelyn, and Silva, F.V.M. 2017. Resistance of Byssochlamys nivea and Neosartorya fischeri

mould spores of different age to high pressure thermal processing and thermosoni­

cation. Journal of Food Engineering 201:9–16. FDA, 1992. Foodborne Pathogenic Microorganisms and Natural Toxins Handbook. US Food

and Drug Administration, Center for Food Safety & Applied Nutrition. http://www.fda .gov/downloads/Food/FoodborneIllnessContaminants/UCM297627.pdf.

FDA. 2011. Bacteriological Analytical Manual, Chapter 4: Diarrheagenic Escherichia coli.

Ferreira, E.H.R., Rosenthal, A., Calado, V., Saraiva, J., and Mendo, S. 2009. Byssochlamys nivea inactivation in pineapple juice and nectar using high pressure cycles. Journal of Food Engineering 95(4):664–669.

Garcia-Armesto, M.R., and Sutherland, A.D. 1997. Temperature characterization of psy-

chrotrophic and mesophilic Bacillus species from milk. Journal of Dairy Research

64:261–270. Georget, E., Sevenich, R., Reineke, K., Mathys, A., Heinz, V., Callanan, M., Rauh, C., and

Knorr, D. 2015. Inactivation of microorganisms by high isostatic pressure processing in

complex matrices: A review. Innovative Food Science & Emerging Technologies 27:1–

14. Gould, G.W. 1999. Sous vide foods: Conclusions of an ECFF botulinum working party. Food

Control 10(1):47–51. Gould, G.W. 2006. History of science—Spores. Lewis B. Perry Memorial Lecture 2005.

Journal of Applied Microbiology 101(3):507–513. Graham, A.F., Mason, D.R., and Peck, M.W. 1996. Inhibitory effect of combinations of heat

treatment, pH, and sodium chloride on growth from spores of nonproteolytic

Clostridium botulinum at refrigeration temperature. Applied and Environmental

Microbiology 62(7):2664–2668.

34 High Pressure Processing of Fruit and Vegetable Products

Guerrero-Beltrán, J.O.S.É.Á., Barbosa-Cánovas, G.V., and Welti-Chanes, J.O.R.G.E. 2011a.

High hydrostatic pressure effect on Saccharomyces cerevisiae, Escherichia coli and

Listeria innocua in pear nectar. Journal of Food Quality 34(6):371–378. Guerrero-Beltrán, J.A., Barbosa-Cánovas, G.V., and Welti-Chanes, J. 2011b. High hydrostatic

pressure effect on natural microflora, Saccharomyces cerevisiae, Escherichia coli, and

Listeria Innocua in navel orange juice. International Journal of Food Engineering 7(1).

DOI: 10.2202/1556-3758.2166. Heinz, V., and Knorr, D. 2002. Effects of high pressure on spores. In Ultra High Pressure

Treatments of Foods, Eds. Hendrickx, M.E.G. and Knorr, D. New York: Kluwer/

Plenum, pp. 77–114. Hiperbaric. 2015. High pressure processing (HPP) technology as a preservation technique for

foods. Retrieved August 30, 2015, from http://www.malta-consolider.com/download

/sups/13-SUPS_D.Flores-FoodScienceAndTechnology.pdf. Hiremath, N.D., and Ramaswamy, H.S. 2012. High-pressure destruction kinetics of spoil-age

and pathogenic microorganisms in mango juice. Journal of Food Processing and

Preservation 36(2):113–125. Hite, B.H. 1899. The effect of pressure on the preservation of milk. Virginia Agriculture

Experiment Station Bulletin 58:15–35. Houška, M., Strohalm, J., Kocurová, K., Totušek, J., Lefnerová, D., Tříska, J., Vrchotová, N.,

Fiedlerová, V., Holasova, M., Gabrovská, D., and Paulíčková, I. 2006. High pressure and

foods—Fruit/vegetable juices. Journal of Food Engineering 77(3):386–398. Hsu, H., Sheen, S., Sites, J., Huang, L., Wu, J.S. 2014. Effect of high pressure treatment on

the survival of Shiga toxin-producing Escherichia coli in strawberry puree. Food

Microbiology. 40:25–30. Ikeyami, Y., Okaya, C., Samayama, Z., Mori, D., and Oku, M. 1970. Gaseous spoilage by

butyric anaerobes in canned fruits, I. canned mandarin orange. Canners Journal 49(11):993–

996. Jay, J.M. 2000. Intrinsic and extrinsic parameters of foods that affect microbial growth. In Modern Food Microbiology, 6th ed. US: Springer-Verlag, pp. 35–56.

Juneja, V.K., and Marks, H.M. 1999. Proteolytic Clostridium botulinum growth at 12–48°C

simulating the cooling of cooked meat: Development of a predictive model. Food

Microbiology 16:583–592. Karwe, M.V., Maldonado, J., and Mahadevan, S. 2014. High Pressure Processing: Current

Status. In Conventional and Advanced Food Processing Technologies, Ed.

Bhattacharya, S. UK: John Wiley & Sons, Ltd., pp. 595–616. Katsaros, G.I., Tsevdou, M., Panagiotou, T., and Taoukis, P.S. 2010. Kinetic study of high

pressure microbial and enzyme inactivation and selection of pasteurisation condi-tions

for Valencia orange juice. International Journal of Food Science & Technology

45(6):1119–1129. Kuldiloke, J., and Eshtiaghi, M.N. 2008. Application of non-thermal processing for preserva-

tion of orange juice. KMITL Science Technology Journal 8(2):64–74. Lee, S.Y., Dougherty, R.H., and Kang, D.H. 2002. Inhibitory effects of high pressure and heat

on Alicyclobacillus acidoterrestris spores in apple juice. Applied and Environmental

Microbiology 68(8):4158–4161. Lee, S.Y., Chung, H.J., and Kang, D.H. 2006. Combined treatment of high pressure and heat

on killing spores of Alicyclobacillus acidoterrestris in apple juice concentrate. Journal

of Food Protection 69(5):1056–1060. Lindstrom, M., Kiviniemi, K., and Korkeala, H. 2006. Hazard and control of group II (non-

proteolytic) Clostridium botulinum in modern food processing. International Journal of

Food Microbiology 108:92–104. Ma, Y., Hu, X., Chen, J., Zhao, G., Liao, X., Chen, F., Wu, J., and Wang, Z. 2010. Effect of

UHP on enzyme, microorganism and flavour in cantaloupe (Cucumis melo L.) juice.

Journal of Food Process Engineering 33:540–553.

HPP Effect on Microorganisms in Fruit and Vegetable Products 35

Mathys, A., Reineke, K., Heinz, V., and Knorr, D. 2009. High pressure thermal sterilization–

development and application of temperature controlled spore inactivation studies. High

Pressure Research 29:3–7. Merkulow, N., Eicher, R., and Ludwig, H. 2000. Pressure inactivation of fungal spores in aque-ous

model solutions and in real food systems. High Pressure Research 19(1–6):253–262. Murrel, W.G., and Scott, W.J. 1966. The heat resistance of bacterial spores at various water

activities. Journal of General Microbiology 43:411–425. National Advisory Committee on Microbiological Criteria for Foods. 2006. Requisite scien-

tific parameters for establishing the equivalence of alternative methods of pasteuriza-

tion. Journal Food Protection 69(5):1190–1216. Neetoo, H., and Chen, H. 2010. Inactivation of Salmonella and Escherichia coli O157:H7 on

artificially contaminated alfalfa seeds using high hydrostatic pressure. Food

Microbiology 27:332–338. Neetoo, H., and Chen, H. 2012. High pressure inactivation of Salmonella on Jalapeño and

Serrano peppers destined for direct consumption or as ingredients in Mexican salsa and

guacamole. International Journal of Food Microbiology 156:197–203. Neetoo, H., Nekoozadeh, S., Jiang, Z., Chen, H., 2011. Application of high hydrostatic pres-

sure to decontaminate green onions from Salmonella and Escherichia coli O157:H7.

Food Microbiology 28:1275–1283. Norton, T., and Sun, D.W. 2008. Recent advances in the use of high pressure as an effective

processing technique in the food industry. Food and Bioprocess Technology 1:2–34. Palou, E., López-Malo, A., Barbosa-Cánovas, G.V., Welti-Chanes, J., Davidson, P.M., and

Swanson, B.G. 1998. Effect of oscillatory high hydrostatic pressure treatments on

Byssochlamys nivea ascospores suspended in fruit juice concentrates. Letters in Applied

Microbiology 27(6):375–378. Palou, E., Hernández-Salgado, C., López-Malo, A., Barbosa-Cánovas, G.V., Swanson, B.G.,

and Welti-Chanes, J. 2000. High pressure-processed guacamole. Innovative Food

Science & Emerging Technologies 1(1):69–75. Peck, M.W. 2006. Clostridium botulinum and the safety of minimally heated, chilled foods:

An emerging issue? Journal of Applied Microbiology 101(3):556. Peredkov, A. 2004. Botulism, canned eggplant—Kyrgyzstan (Osh). ProMED Mail,

20041203.3225. Parish, M.E. 1998. High pressure inactivation of Saccharomyces cerevisiae, endog-enous

microflora and pectinmethylesterase in orange juice. Journal of Food Safety 18(1):57–

65. Parish, M.E., Narciso, J.A., and Friedrich, L.M. 1997. Survival of Salmonellae in orange juice.

Journal of Food Safety 17(4):273–281. Patterson, M.F., Ledward, D.A., and Rogers, N. 2006. High pressure processing. In Food

Processing Handbook. Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA., pp. 173–

197. Peleg, M., and Cole, M.B. 1998. Reinterpretation of microbial survival curves. Critical

Reviews in Food Science 38:353–380. Pinhatti, M.E.M.C., Variane, S., Eguchi, S.Y., and Manfio, G.P. 1997. Detection of acidother-

mophilic Bacilli in industrialized fruit juices. Fruit Processing 7(9):350–353. Raso, J., Calderón, M.L., Góngora, M., Barbosa-Cánovas, G.V., and Swanson, B.G. 1998.

Inactivation of Zygosaccharomyces bailii in fruit juices by heat, high hydrostatic pres-

sure and pulsed electric fields. Journal of Food Science 63(6):1042–1044. Reineke, K., Mathys, A., Heinz, V., and Knorr, D. 2013. Mechanisms of endospore inactiva-

tion under high pressure. Trends in Microbiology 21:296–304. Rendueles, E., Omer, M., Alvseike, O., Alonso-Calleja, C., Capita, R., and Prieto, M. 2011.

Microbiological food safety assessment of high hydrostatic pressure processing: A

review. LWT—Food Science and Technology 44(5):1251–1260.

36 High Pressure Processing of Fruit and Vegetable Products

Ríos-Romero, E., Tabilo-Munizaga, G., Morales-Castro, J., Reyes, J.E., Pérez-Won, M., and

Ochoa-Martínez, L.A. 2012. Efecto de la aplicación de alta presion hidrostática sobre la

inactivación microbiana y las propiedades fisicoquímicas de arilos de granada. CyTA-

Journal of Food 10(2):152–159. Rozali, S.N.M. 2015. Studies on the mechanisms of microbial spore inactivation by elec-tron

microscope observations. Final year project, Chemical and Materials Engineering

Department, University of Auckland, New Zealand. Shridhar, P., and Shankhapal, K.V. 1986. Bacterial spoilage of canned mango pulp and green

garden peas. Indian Journal of Microbiology 26(12):39–42. Silva, F.V.M., Gibbs, P.A., Vieira, M.C., and Silva, C.L.M. 1999. Thermal inactivation of

Alicyclobacillus acidoterrestris spores under different temperature, soluble solids and

pH conditions for the design of fruit processes. International Journal of Food

Microbiology 51(2−3):95–103. Silva, F.V.M., and Gibbs, P.A. 2001. Alicyclobacillus acidoterrestris spores in fruit prod-ucts

and design of pasteurization processes. Trends in Food Science and Technologies

12(2):68–74. Silva, F.V.M., and Gibbs, P.A. 2004. Target selection in designing pasteurization processes

for shelf-stable high-acid fruit products. Critical Reviews in Food Science and Nutrition

44(5):353–360. Silva, F.V.M., and Gibbs, P.A. 2009. Principles of thermal processing: Pasteurization. In

Engineering Aspects of Thermal Food Processing. Ed. Simpson, R. Contemporary Food

Engineering Series. Boca Raton, USA: CRC Press, Taylor & Francis Group, pp. 13–48. Silva, F.V.M., Tan, E.K., and Farid, M. 2012. Bacterial spore inactivation at 45–65°C using

High Pressure Processing: Study of Alicyclobacillus acidoterrestris in orange juice.

Food Microbiology 32(1):206–211. Silva, F.V.M., Gibbs, P.A., Nunez, H., Almonacid, S., and Simpson, R. 2014. Thermal

Processes: Pasteurization. In Encyclopedia of Food Microbiology. Eds. Batt, C.A., and

Tortorello, M.L., Amsterdam: Elsevier, pp. 577–595. Sinell, H.J. 1980. Interacting factors affecting mixed populations in microbial ecology of

foods, Vol. 1, ed. Silliker J.H., Academic Press, New York, 215 pp. Sinigaglia, M., Corbo, M.R., Altieri, C., Campaniello, D., D’amato, D., and Bevilacqua, A.

2003. Combined effects of temperature, water activity, and pH on Alicyclobacillus acidoterrestris spores. Journal of Food Protection 66(12):2216–2221.

Sokołowska, B., Skąpska, S., Fonberg-Broczek, M., Niezgoda, J., Chotkiewicz, M.,

Dekowska, A., and Rzoska, S.J. 2013. Factors influencing the inactivation of

Alicyclobacillus acidoterrestris spores exposed to high hydrostatic pressure in apple

juice. High Pressure Research 33(1):73–82. Sulaiman, A., and Silva, F.V.M. 2013. High pressure processing, thermal processing and

freezing of ‘Camarosa’ strawberry for the inactivation of polyphenoloxidase and con-

trol of browning. Food Control 33(2):424–428. Sulaiman, A., Soo, M.J., Yoon, M.M., Farid, M., and Silva, F.V.M. 2015. Modeling the poly-

phenoloxidase inactivation kinetics in pear, apple and strawberry purees after high

pressure processing. Journal of Food Engineering 147:89–94. Sulaiman, A., Farid, M., and Silva, F.V.M. 2017. Strawberry puree processed by thermal, high

pressure, or power ultrasound: Process energy requirements and quality modeling dur-

ing storage. Food Science and Technology International 23(4): 293–309. Teo, A.Y.L., Ravishankar, S., and Sizer, C.E. 2001. Effect of low-temperature, high-pressure

treatment on the survival of Escherichia coli O157:H7 and Salmonella in unpasteurized

fruit juices. Journal of Food Protection 64(8):1122–1127. Therre, H. 1999. Botulism in the European Union. Eurosurveillance 4:2–7.

HPP Effect on Microorganisms in Fruit and Vegetable Products 37

Tola, Y.B., and Ramaswamy, H.S. 2014. Combined effects of high pressure, moderate heat

and pH on the inactivation kinetics of Bacillus licheniformis spores in carrot juice. Food

Research International 62:50–58. Uchida, R., and Silva, F.V.M. 2017. Alicyclobacillus acidoterrestris spore inactivation by high

pressure combined with mild heat: Modelling the effect of temperature and soluble

solids. Food Control 73:426–432. Van Boekel, M.A.J.S. 2002. On the use of the Weibull model to describe thermal inactivation of

microbial vegetative cells. International Journal of Food Microbiology 74:139–159. Van Buggenhout, S., Messagie, I., Van der Plancken, I., and Hendrickx, M. 2006. Influence

of high-pressure–low-temperature treatments on fruit and vegetable quality related

enzymes. Journal of European Food Research and Technology 223(4):475–485. Van Loey, A., Smout, C., and Hendrickx, M. 2003. High hydrostatic pressure technology in

food preservation. In Food Preservation Techniques, Eds. Zeuthen, P., and Bogh-

Sorensen, L. Cambridge, UK: Woodhead Publishing Limited, pp. 428–448. Van Opstal, I., Vanmuysen, S.C.M., Wuytack, E.Y., Masschalck, B., and Michiels, C.W. 2005.

Inactivation of Escherichia coli by high hydrostatic pressure at different temperatures in

buffer and carrot juice. International Journal of Food Microbiology 98:179–191. Vercammen, A., Vanoirbeek, K.G., Lemmens, L., Lurquin, I., Hendrickx, M.E., and Michiels,

C.W. 2012. High pressure pasteurization of apple pieces in syrup: Microbiological shelf-life and quality evolution during refrigerated storage. Innovative Food Science &

Emerging Technologies 16:259–266. Voldřich, M., Dobiáš, J., Tichá, L., Čeřovský, M., and Krátká, J. 2004. Resistance of vegeta-

tive cells and ascospores of heat resistant mould Talaromyces avellaneus to the high

pressure treatment in apple juice. Journal of Food Engineering 61(4):541–543. Weibull, W.D. 1951. A statistical distribution function of wide applicability. Journal of

Applied Mechanics 18:293–297. World Health Organization, 2002. Foodborne Diseases, Emerging. Fact Sheet No. 124.

https://apps.who.int/inf-fs/en/fact124.html. Zimmermann, M., Schaffner, D.W., and Aragão, G.M.F. 2013. Modeling the inactiva-tion

kinetics of Bacillus coagulans spores in tomato pulp from the combined effect of high

pressure and moderate temperature. LWT—Food Science and Technology 53(1):107–

112. Zook, C., Parish, M., Braddock, R., and Balaban, M. 1999. High pressure inactivation kinet-

ics of Saccharomyces cerevisiae ascospores in orange and apple juices. Journal of Food

Science 64(3):533–535.