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Comparison of -tocopherol microparticles produced with different wall materials:pea protein a new interesting alternativeAnna Paola T. R. Pierucci ab; Leonardo R. Andrade c; Marco Farina c; Cristiana Pedrosa a; Maria Helena M.Rocha-Leão bd

a Departamento de Nutrição Básica e Experimental, Instituto de Nutrição, Centro de Ciências da Saúde,Universidade Federal do Rio de Janeiro, b Programa de Pós-Graduação em Ciências de Alimentos, Institutode Química, Universidade Federal do Rio de Janeiro, c Departamento de Histologia e Embriologia, Institutode Ciências Biomédicas, Universidade Federal do Rio de Janeiro, d Departamento de EngenhariaBioquímica, Escola de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil

Online Publication Date: 01 January 2007

To cite this Article Pierucci, Anna Paola T. R., Andrade, Leonardo R., Farina, Marco, Pedrosa, Cristiana and Rocha-Leão, MariaHelena M.(2007)'Comparison of -tocopherol microparticles produced with different wall materials: pea protein a new interestingalternative',Journal of Microencapsulation,24:3,201 — 213

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Journal of Microencapsulation, May 2007; 24(3): 201–213

Comparison of a-tocopherol microparticles producedwith different wall materials: pea protein a newinteresting alternative

ANNA PAOLA T. R. PIERUCCI1,2, LEONARDO R. ANDRADE3,

MARCO FARINA3, CRISTIANA PEDROSA1, & MARIA HELENA

M. ROCHA-LEAO2,4

1Departamento de Nutricao Basica e Experimental, Instituto de Nutricao, Centro de Ciencias da

Saude, Universidade Federal do Rio de Janeiro, 2Programa de Pos-Graduacao em Ciencias de

Alimentos, Instituto de Quımica, Universidade Federal do Rio de Janeiro, 3Departamento de

Histologia e Embriologia, Instituto de Ciencias Biomedicas, Universidade Federal do Rio de Janeiro,

and 4Departamento de Engenharia Bioquımica, Escola de Quımica, Universidade Federal do Rio de

Janeiro, Rio de Janeiro, Brazil

(Received 25 September 2006; revised 9 January 2007; accepted 14 February 2007)

Abstract�-Tocopherol is a radical chain breaking antioxidant that can protect the integrity of tissues and play animportant role in life process. Microparticles containing �-tocopherol were produced by spray dryingtechnique using pea protein (PP), carboxymethylcellulose(CMC) and mixtures of these materials withmaltodextrin (PP-M and CMC-M) as wall materials. The microparticles produced were characterisedas regards the core retention (high performance liquid chromatography), the morphology (scanningelectron microscopy) and size distribution (laser diffraction). The retention of �-tocopherol within allmicroparticles was above 77%. They showed a spherical shape and roughness at varied degrees. Theirmean particles size remained below 7 mm, and the smallest sizes were found in PP and CMC-Mmicroparticles. The results obtained in this work show that the pea protein use for �-tocopherolmicroencapsulation is a promising system for further application in food.

Keywords: Carboxymethylcellulose, microparticles, pea protein, spray drying, tocopherol

Introduction

�-Tocopherol, the active form of vitamin E, is a radical chain breaking antioxidant that

can protect the integrity of tissues and play an important role in life process. This vitamin

is considered one of the most important dietetic antioxidant for human nutrition,

being located in all cell membranes, especially in the internal mitochondrial membrane

Correspondence: Anna Paola T. R. Pierucci, Av. Brigadeiro Trompowski, s/n�, CCS, Bl J, 2� andar. Ilha do Fundao. Rio de

Janeiro, RJ 21940 590, Brazil. Tel: (þ5521) 2560 8293. Fax: (þ5521) 2560 8293. E-mail: pierucci@nutricao.ufrj.br

ISSN 0265–2048 print/ISSN 1464–5246 online � 2007 Informa UK Ltd.

DOI: 10.1080/02652040701281167

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(Azzi and Stocker 2000). The intake of �-tocopherol helps to lower the risk of chronic

diseases, such as heart diseases, hypertension, type 2 diabetes, cancer and Alzheimer’s

disease. Yet, many individuals fail to meet the current recommendation for vitamin E intake

(Maras et al. 2004). So, food fortification with this vitamin would improve �-tocopherolintake in the diets.

The application of �-tocopherol in food is limited due to its high hydrophobicity and

instability against oxygen and UV (Azzi and Stocker 2000). Recently, efforts have been made

to develop systems for protection and delivery of active agents, and nano- and

microparticles, which are containers surrounding functional material with a polymer

membrane in the size of about 50 nm to 2mm, are being increasingly introduced (Park and

Kim 2005). Most of the published research that approached the development of these

systems involving tocopherol describes its utilisation as an antioxidant additive for the

protection of bioactive substances, such as fish oils (Baik et al. 2004), ascorbic acid (Sharma

and Lal 2005) and retinol (Lee et al. 2002). The few published works that reported the

encapsulation of tocopherol for its own protection and/or controlled release purposes,

describe encapsulation with varied wall materials by oil-in-water emulsion solvent

evaporation technique (Mojovic et al. 1996; Duclairoir et al. 2002; Park and Kim 2005).

Until now, reports on tocopherol encapsulation by spray drying were not found in the

literature.

Spray drying is the most commonly used technology for the production of microparticles.

This method is based in the atomisation of an aqueous in feed material (water, carrier, and

active agent) into a stream of hot air, and the dried droplets (powder) are recovered via

cyclone collectors. A great interest in the area of microencapsulation by spray drying is the

research for new natural biocompatible materials to act as carriers of bioactive substances

(Gouin 2004).

Legume seeds have attracted increasing attention with regard to the use of storage proteins

as functional agents in food development (Pedrosa et al. 2000). Recent studies supported

technological utilisation of pea proteins by exploring properties such as emulsification,

gelation and film formation (Choi and Han 2002; Rangel et al. 2003). Previous work from

our laboratories demonstrated the use of pea protein as a coating agent for the

microencapsulation of ascorbic acid in the development of a gastric delivery system

(Pierucci et al. 2006). These findings and the low cost of the material as a source of proteins

suggested us to perform this work, aiming at the production of microparticles, by spray

drying, using pea protein as wall material of �-tocopherol. The already known materials

carboxymethylcellulose and maltodextrin (and blends) were also used as reference wall

materials to draw a comparison. Characterisation of the microparticles was performed by

analysing �-tocopherol retention, as well as morphology, size distribution and stability

within specially designed food health purposes.

Materials and methods

Microparticles wall and core materials

Pea protein concentrate (Propulse, Parrheim foods, Canada), which is a natural food grade

product, obtained from seeds of Pisum sativum, constituted by 82% of proteins, according to

the manufacturer; sodium-carboxymethylcellulose (PE 31 FG, Latinoquımica, Argentina),

with average viscosity in 2% solution 100–500 cps and degree of substitution (average

number of carboxymethyl groups per glucose units) 0.65–0.85, as informed by the

202 A. P. T. R. Pierucci et al.

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manufacturer; and maltodextrin (MOR REX 1910-Corn Products, Brazil) were used as wall

materials; tocopherol (BASF Human Nutrition, Brazil) was the core material.

Characterisation of wall materials

The wall materials, pea protein concentrate (PP), sodium-carboxymethylcellulose (CMC)

and maltodextrin (M), were analysed for their proximate composition – moisture content,

crude ash, crude lipid and crude protein, by the standard method of the Association of

Official Analytical Chemists (AOAC 1995), and carbohydrate content was calculated as the

difference between 100% and the combined % moisture, ash, crude protein and total lipid.

All those analysis were performed in triplicate. The wall material PP was also analysed by

electrophoresis. SDS-PAGE was performed according to the method of Laemmli (1970),

using 15% (w/v) acrylamide (4% acrylamide stacking gels). The sample loading buffer

contained 50mM Tris-Cl (ph 6.8), 15% (v/v) glycerol, 0.025% (w/v), bromophenol blue,

and 2% (w/v) SDS. Protein bands were stained with Coomassie brilliant blue R. The

molecular weight markers were performed using bovine albumin (66 kDa), anidrase

carbonic (29 kDa), �-lactoglobulin (18.4 kDa) and lysosime (14.3 kDa) as standards.

Production of microparticles

Microparticles were obtained by spray-drying feed emulsions, composed by distilled water

and wall and core materials. Each one of the wall material PP and CMC was applied isolated

or blended with M, in a ratio of 1:1 (w/w), making a total of four feed emulsions, as follows:

(1) PP, composed by PP isolated and T, in a ratio of 2:1 (w/w); (2) PP-M, composed

by PP blended with M and T, in a ratio of 1:1:1 (w/w/w); (3) CMC, composed by CMC

isolated and T, in a ratio of 2:1 (w/w); and (4) CMC-M, composed by CMC blended with

M and T, in a ratio of 1:1:1 (w/w/w). The feed emulsions were prepared as follows: firstly the

wall materials were added into distilled water and homogenised with an electronic agitator

(Quimis Q250) at 300 rpm for 5min; in the sequence, the core (T) was emulsified by slowly

dropping into the homogenised solutions, under continuous stirring with the agitator. The

feed emulsions were immediately dried in the spray dryer. The dying process was performed

in a Mini Spray Dryer Buchi 190 (Buchi Laboratory Equipment, Switzerland), inlet air

temperature at 180�C and outlet at 90�C, nozzle of 0.3mm, and 1Lh�1 feed rate. The

microparticles were collected from the container, closed hermetically in an opaque

packaging and stored in desiccators at room temperature.

Physical-chemical parameters

The total solids in feed emulsions and moisture content (water content) in microparticles

were analysed by gravimetric method as cited above. The pH value of dispersions were

analysed in a potentiometer INCIBRAS at 25�C. Apparent viscosity (�ap) of the feed

emulsions was measured in a viscosimeter with coaxial cylinders, Contraves Rheomat 30

(Contraves, Zurich, Switzerland) with the thermostatic bath adjusted at 30�C and measuring

systems MS0 for the PP, PP-M and CMC-M samples and DIN25 for the CMC sample.

The tocopherol content was determined by high performance liquid chromatography

(HPLC), performed in a Shimadzu LC10 liquid chromatograph system (Shimadzu Oceania,

Australia) equipped with a 2ml sample loop and a Shimadzu UV detector set at 294 nm,

using a stainless steel, 150� 4mm, C18 (5 mm) column (Symmetry-Waters) operated at

ambient temperature. The mobile phase was metanol/acetonitrile, 30:70%, and flow rate

1.0ml/min (Sanchez-Machado et al. 2002).

Comparison of �-tocopherol microparticles produced with different wall materials 203

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Retention of the core material

The retention of tocopherol was determined as a percentage, based on the tocopherol

content per total solids of feed emulsions and the tocopherol content per total solids of the

microparticles.

Microparticles morphology

Morphology of the wall materials and the microparticles was examined by scanning electron

microscopy (SEM). The particles were deposited on conductive carbon double-faced

adhesive tape on aluminum SEM stubs, and sputter-coated with gold (Balzers Union,

FL-9496 – Balzers, Germany). The samples were observed in a JSM 5310 (JEOL, Tokyo,

Japan), operated at 15 kV.

Particle size distribution

Particle size distribution was determined by the scattering pattern of a transverse laser light

using the equipment MAF 5001 Malvern Mastersizer Plus (Malvern Instruments Inc.,

Worcestershire, England), that determines the particle diameters’ distribution ranging from

0.05 to 550 mm.

Stability of microencapsulated tocopherol into a food matrix

To study the stability of microencapsulated T with the different wall materials into a food

matrix we used as a model of food a high carbohydrate supplement previously developed by

our research group (Pierucci et al. 2000). The food is a natural orange flavoured gel,

composed of a blend of hydrocolloids, a mixture of carbohydrates and some additives as

nor-bixin (Christian Hansen), orange emulsion flavoring (IFF), citric acid (Merk) and

sodium benzoate and potassium sorbate (Pharmus), formulated as described by Pierucci

et al. (2000). The resume of the food (gel) chemical and physical characteristics is listed in

Table I. The amount of gel prepared was divided into five batches for the incorporation

of non-encapsulated T and each of the microparticles (PP, PP-M, CMC and CMC-M).

The amount of T added into the batches of gel was fixed in 400mg g�1. All gels were

packaged in 30 g transparent plastic sachets, sealed at 70�C and stored for 90 days at

Table I. Chemical and physical characteristics of the high carbohydrate

supplement (X�SD).

Variables Values

Moisture content (%) 35.21� 0.45

Ashes (%) 0.14� 0.02

Proteins (%) 0.96� 0.01

Lipids (%) ND

Total carbohydratre (%) 64.00� 0.47

Soluble solids (�Brix) 63.5� 0.50

pH 3.20� 0.00

Acidity in citric acid (%) 0.33� 0.00

Water activity (Aw) 0.92� 0.00

Apparent viscosity (mPa s�1) (30�C; �¼ 100 s�1) 1148.96� 76.06

ND¼not detected

204 A. P. T. R. Pierucci et al.

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room temperature (25�C). The tocopherol content was determined by HPLC, as cited

above, at 0, 15, 30, 45, 60 and 90 days of storage.

Statistical analysis

All the data were evaluated by applying ANOVA one-way analysis, at 5% significance. The

curves from retention data of T in the gel were fitted by regression analysis and rate

constants were calculated. All these were performed using the software Estatistica 5.0.

Results and discussion

The wall materials PP, CMC and M, were analysed for proximate composition and the

results are shown in Table II. According to information given by the PP manufacturer

(Parrheim Foods), our results show that this material is predominantly constituted of

proteins (82%), but also presents 11% of carbohydrates. CMC and M were characterised as

only carbohydrates. White et al. (2003) characterised MOR REX 1910 by high performance

anion-exchange chromatography-pulse amperometric detection and size exclusion chroma-

tography multi-angle light-scattering refractive index detection, and identified carbohydrates

of varied molecular weight, such as glucose, maltose, maltotriose and also carbohydrates

with 30 units of glucose, but carbohydrates constituted by chains between 10 and 20 units of

glucose were predominant.

The pattern of the proteins demonstrated in the electrophoresis (SDS-PAGE) of PP

(Figure 1) exhibited molecular weight in the range of 66 kDa to 14 kDa. According to the

literature, these results indicated that the major proteins from PP are legume storage

proteins, such as vicilin (Bewley and Black 1985; Pedrosa et al. 2000).

The physical-chemical parameters of the feed emulsions and microparticles are presented

in Table III. Total solids, tocopherol content, pH and viscosity of feed emulsions were

influenced by the amounts and nature of each wall material used in the formulations. The

water content of PP and PP-M microparticles was approximately 8% (w/w), while CMC and

CMC-M was approximately 2.5% (w/w). The PP and CMC microparticles showed similar

core retention values (p<0.05), but CMC-M showed the highest retention (96.7� 0.21).

The mixtures of maltodextrin with each PP and CMC had the opposite effect on core

retention, being reduced in the first case (PP-M) and increased in the second one (CMC-M)

(Table III).

The results reported here show that the retention of tocopherol in the different wall

materials comprised between 77% (PP-M) and 96% (CMC-M), which was considered

optimum in respect to the applied drying technology. The mixture of maltodextrin with PP

Table II. Proximate composition of the wall materials, Pea protein concentrate (PP), sodium-carboxymethyl-

cellulose (CMC) and maltodextrin (M) (X�SD).

Variables PP CMC M

Moisture content (%) 6.0� 1.0 2.5� 0.8 4.3� 1.0

Crude ashes (%) 0.4� 0.1 0.2� 0.03 0.1� 1.0

Protein (%) 82� 2.0 0.12� 0.01 ND

Lipids (%) 1.0� 0.2 ND ND

Carbohydrates (%) 11.0� 1.0 97.2� 1.0 95.6� 1.0

ND¼not detected.

Comparison of �-tocopherol microparticles produced with different wall materials 205

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(PP-M) had the feed emulsion destabilised, which produced lower retention of tocopherol

compared to PP isolated. However, in the mixture of maltodextrin with CMC (CMC-M)

the retention was enhanced due to the decrease of viscosity of feed emulsions, which

favoured the atomisation and drying rate of the feed (Table III).

The retention of hydrophobic molecules in the spray-drying process can be significantly

low depending on the stability of emulsion. Liu et al. (2001), demonstrated that spray-dried

hydrophobic flavours in gum Arabic matrix had 20% of retention. On the other hand, Shi

and Tan (2002) related retention above 95% of vitamin D2 within chitosan matrix.

Lane 1 Lane 2

66 kDa

29 kDa

18.6 kDa

14.3 kDa

Figure 1. SDS-PAGE; standard proteins in lane 1 and pea protein concentrate (PP) in lane 2.Arrows indicate molecular masses of proteins.

Table III. Physical-chemical parameters of the feed emulsions and of the microparticles with the varied wall

materials investigated and retention of tocopherol in the microparticles (X�SD).

Total Solids* Moisture content Tocoferol* pH Viscosity# Core retention

Samples (%) w/w (%) w/w (mgml�1) (mPa.s) (%)

Feed Emulsions

PP 14.6 – 4.88 4.5� 0.00 10.6�0.41 –

PP-M 14.6 – 4.88 4.5� 0.01 6.7�0.20a –

CMC 7.50 – 2.5 5.0� 0.00 120.7�1.22a –

CMC-M 7.50 – 2.5 5.0� 0.00 40.6�1.32b,c –

Microparticles

PP – 8.8� 0.15 28.0�0.21 – – 86.8� 0.10

PP-M – 8.5� 0.25 25.1�0.02a – – 77.8� 0.04a

CMC – 2.2� 0.25a,b 29.9�0.03a,b – – 87.1� 0.01c

CMC-M – 2.9� 0.25a,b 32.2�0.22a,b,c – – 96.7� 0.21a,b,c

*Data from feed emulsions based on the respective formulations; Apparent viscosity measured at 30�C undershear rate (�) 100.00 s�1; aSignificantly different from PP ( p<0.05); bSignificantly different from CMC ( p<0.05);cSignificantly different from PP-M ( p<0.05).

206 A. P. T. R. Pierucci et al.

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The retention data reported by researchers that applied solvent evaporation technique for

the microencapsulation of tocopherol, revealed that gliadin had 77% retention (Duclairoir

et al. 2002), while liposome had 88% and 93%, depending on the preparation technique of

liposome (Mojovic et al. 1996).

CMC has been extensively used to enhance solubility of hydrophobic drugs due to its

emulsion forming property (Feddersen and Thorp 1993). The similarity of retention data

between CMC and PP indicated the latter exhibits great potential to stabilise feed emulsion

and retain tocopherol during drying. PP as wall material of bioactive substances for food

application is more advantageous in relation to CMC. This occurs firstly because PP is a

relatively inexpensive source of natural proteins, and secondly due to its biodegradability

and compatibility for delivery of active agents into the stomach. PP might promote total

disposability of an active substance for human absorption, through the matrix erosion release

mechanism by the action of gastric enzymes.

The SEM images showed that all microparticles produced with the varied wall materials

had spherical geometry but differed as regards their surface topography. The PP and PP-M

samples were characterised by an intense invagination and roughness (Figures 2 and 3),

while CMC samples had a predominantly smooth surface, and CMC-M samples had

2

Figure 2. Scanning electron micrograph (SEM) of microparticles coated with PP showing theinvagination and the roughness surface.

3

Figure 3. SEM of the microparticles coated with PP blended with M presenting similar morphologyto PP isolated ones.

Comparison of �-tocopherol microparticles produced with different wall materials 207

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roughness to a lesser extent than PP or PP-M (Figures 4 and 5). As regards the particle size

distribution, PP had lower mean particle diameter (2.20� 0.05 mm) than PP-M

(3.52� 0.2 mm) while CMC had higher mean particle diameter (7.77� 0.23 mm), than

CMC-M (1.45� 0.01 mm).

Previous study from our laboratories described the production of ascorbic acid

microparticles coated by PP, CMC and mixtures with M, by spray-drying technique.

Accordingly, PP microparticles were intensely rough and invaginated while CMC and

CMC-M were very smooth (Pierucci et al. 2006). Spray-dried materials are usually hollow

spheres (Re 1998), however, the nature of the wall materials and its modification by the

drying process may influence the surface characteristics of microparticles. It seems that, in

cases where protein and carbohydrate blends are used as wall materials in microparticulate

systems, proteins serves as an emulsifying and film-forming agent, while carbohydrates act as

a matrix forming material (Young et al. 1993).

Here we verified that the mixture of maltodextrin with PP (PP-M) in relation to PP

isolated, increased particle size significantly, but did not affect surface morphology

(Figures 2 and 3). Sheu and Rosenberg (1998) verified that whey proteins at a ratio

4

Figure 4. SEM of the microparticles coated with CMC showing the spherical microparticles withsmooth surfaces.

5

Figure 5. SEM of the microparticles coated with the blend CMC/M presenting rough surfacemorphology.

208 A. P. T. R. Pierucci et al.

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of 1:1 to maltodextrin, or higher, improved the surface smoothness and decreased surface

indentation of maltodextrin-based microparticles. The presence of irregularities on the

surface of microparticles might influence on their flux properties (Boultboul et al. 2002).

Thus, the adoption of varied processing conditions, such as total solids of feed emulsions

and the ratio of wall materials, is eventually needed to minimise the formation of depressions

on the surface of microparticles.

The topography of CMC and CMC-M samples was quite different (Figures 4 and 5), and

this was related to the size distribution of those microparticles. The observation of smaller

particle sizes in CMC-M samples compared to CMC ones were attributed to the decrease of

viscosity of feed emulsions. The lower viscosity favoured the atomisation and production

of high drying rates, leading to rapid wall solidification when smoothing cannot occur.

Particle diameter may be enhanced when air expansion inside microparticles occurs before

dry crust is formed, which also diminishes the surface roughness (Sheu and Rosenberg

1998). In addition, very high viscosity compromises the proper formation of droplets during

the atomisation stage, resulting in large particles (Re 1998).

According to Walton and Munford 1999, rough and/or invaginated surfaces of

microparticles lead to acceleration of the release of the encapsulated material due to a

greater superficial area in contact with the medium. However, it is also indicated that the

encapsulating ability of a material is given by the degree of integrity and porosity of

microparticles (Sheu and Rosenberg 1998). Here, we demonstrated that open pores were

observed in PP, PP-M and CMC microparticles (Figures 6–8).

The highest retention of tocopherol (Table III) was observed in CMC-M microparticles,

where open pores were not observed (Figure 9). The presence of pores is unfavourable for

the protection efficacy by wall materials, against oxygen and UV action on the core

molecule. However, the high core retention observed in PP microparticles suggests an

interaction between those molecules. Pea proteins have isoelectric point at pH 5–6, where

the molecules are strongly folded (Pedrosa et al. 2000). The pH of feed emulsions

(Table III) favoured the unstable the dynamics conformation of proteins, exposing the

charges from amino acids. This, presumably, induced electrostatic interactions between

tocopherol and pea proteins.

The tocopherol free and microencapsulated in the different wall materials were added into

a food gel and stored for 90 days for the time-course control of tocopherol content.

The retention curves of tocopherol along the time of storage are presented in Figure 10.

6

Figure 6. SEM of the sample PP, showing the presence of an open pore and coalescence of smallermicroparticles.

Comparison of �-tocopherol microparticles produced with different wall materials 209

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9

Figure 9. SEM of the sample CMC-M showing microparticles without open pores.

7

Figure 7. SEM of the sample PP-M showing a microcapsule with an open pore and coalescence ofsmaller particles.

8

Figure 8. SEM of the sample CMC showing the presence of an open pore in one microparticle.

210 A. P. T. R. Pierucci et al.

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The free tocopherol content decreased significantly more than all of the microencapsulated

ones, which demonstrate that the microencapsulation processes were effective in the

protection of tocopherol, independently of the type of wall material. The tocopherol content

of PP-M microparticles decreased as much as T, during the first 15 days of storage. The PP

and CMC microparticles had higher initial decrease in tocopherol content than CMC-M,

but this profile changed towards the end of storage period, where PP had higher tocopherol

content than all other microparticles. The rapid decrease in tocopherol content of PP and

CMC samples was related to the presence of the observed open pores in those microparticles

(Figures 6–8). It was considered that physical-chemical properties of the wall materials

played important roles in the maintenance of tocopherol content within the food matrix.

As cited in the literature, CMC forms three-dimensional nets through hydrogen bonds with

the aqueous medium, resulting in the increase of apparent viscosity (Feddersen and Thorp

1993). This contributes to the formation of a diffusion barrier around microparticles in

contact with the dissolution medium, hindering tocopherol to cross over and retarding the

release from CMC and CMC/M microparticles. On the other way, the pH of the food gel

(Table I) is near by isoelectric points of proteins from PP, which favoured the retention of

tocopherol inside protein molecules. The association of M with PP interfered negatively in

the conformational stability of proteins, which might have favoured the higher decrease of

tocopherol compared to PP microparticles (Figure 10).

The microparticles’ morphology, size distribution and core retention are fundamental

parameters that must be investigated when microparticulate systems are developed.

Different studies that approached the development and characterisation of microparticles

demonstrated that the parameters cited above directly interfere with the stability and release

profile of the encapsulated material (Yamamoto et al. 2002; Roos 2003). Thus, the

productions of small and homogeneous particles, with high core retention and without

defects are needed for a satisfactory system control. Here we demonstrated that

0

20

40

60

80

100

120

0 20 40 60 80 100

Time (days)

Toc

ophe

rol c

onte

nt (

%)

T

PP-M

PP

CMC-M

CMC

** *

*

Figure 10. Retention curves of �-Tocopherol free (T) and microencapsulated in the different wallmaterials, pea protein (PP), pea protein blended with matodextrin (PP-M), carboxymethylcellulose(CMC) and carboxymethylcellulose blended with maltodextrin (CMC-M), added into the food gel,during 90 days storage. *samples with similar �-tocopherol content ( p<0.05): 15 days – T and P, PPand CMC; 30 days – PP and CMC; 45 days – PP and CMC-M; 60 days – CMCM and CMC.

Comparison of �-tocopherol microparticles produced with different wall materials 211

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microparticles with open pores may have a rapid initial decrease of tocopherol content within

a food gel matrix, but the final stability of tocopherol was not compromised.

According to our results, microparticles with high tocopherol retention and stability can

be produced using PP as wall materials. The mixture of maltodextrin with CMC can provide

great modifications on the core retention, morphology and particle sizes of microparticles.

Although the mixture of maltodextrin with PP had no effect on surface morphology of

particles it seemed to reduce core retention and stability. Thus, the use of maltodextrin was

beneficial in association with CMC but not with PP. The presence of pores in some

microparticles resulted in the slight reduction of core retention, but did not compromise the

retention quality or final stability of those. Our next step will be to study the release kinetics

of the tocopherol microparticles in simulated human gastric and enteric conditions.

This comparative study is of great importance since CMC, being a well known material

used in the coating process of hydrophobic active substances, was useful to validate the use

of PP as a natural alternative material for the microencapsulation process of tocopherol by

spray drying. This, allied to the fact that PP is a good source of proteins for human health

and nutrition, support its application as wall material of active biomaterials in the

development of novel foods for specific health purposes.

Acknowledgements

Parrheim Foods, Canada, for the PPC (Propulse); Colloids Naturales for the CMC; Corn

Products Brazil for the M; and BASF-Human Division, Brazil, for the ascorbic acid.

Financial Support: Capes; CNPq/PRONEX; Institutos do Milenio/CNPq.

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