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Journal of Cereal Science 48 (2008) 686–697

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Journal of Cereal Science

journal homepage: www.elsevier .com/locate/ jcs

Influence of formulation and process on the aromatic profileand physical characteristics of bread

Pauline Poinot, Gaelle Arvisenet*, Joelle Grua-Priol, Dorothee Colas,Catherine Fillonneau, Alain Le Bail, Carole ProstENITIAA, UMR GEPEA CNRS 6144, Nantes Atlantique Universites, Rue de la Geraudiere, 44322 Nantes Cedex 3, France

a r t i c l e i n f o

Article history:Received 20 July 2007Received in revised form 10 March 2008Accepted 14 March 2008

Keywords:BreadOdourPartial bakingVolatile compounds

Abbreviations: ANOVA, analysis of variance; HS-Smicroextraction; LRI, linear retention index; LSD, leasidentification based on standard MS spectra databasesPCA, principal component analysis; R1, recipe 1; R2recipe 1/conventional process; R1FBF, recipe 1/fullyrecipe 1/frozen dough process; R2FD, recipe 2/frozen1/partially baked process; R3PB, recipe 3/partially bapartially baked frozen process; rpm, rotations per minon standard injection; tan, tangent.

* Corresponding author. Tel.: þ33 2 51 78 55 12; faE-mail address: arvisenet@enitiaa-nantes.fr (G. Ar

0733-5210/$ – see front matter � 2008 Elsevier Ltd.doi:10.1016/j.jcs.2008.03.002

a b s t r a c t

This work consisted of two complementary sets of experiments in which breads differing in theirrecipe and/or process were characterised according to their odorant perception, volatile compoundcomposition and physical properties. The results revealed that commercial partially baked and/orpartially baked frozen breads were characterised by a different odour compared to commercial con-ventional, fully baked frozen and frozen dough breads, which were perceived similarly. These differ-ences were explained by their variable aromatic composition. By analysing breads based on the samerecipe but from different processes, it was demonstrated that adding a freezing stage before doughproofing or at the end of the conventional process, as well as after partial baking, did not influencebread aroma. Likewise, partial baking had no effect on bread odour and aromatic profile. Thus, thearomatic differences between commercial conventional, fully baked frozen and frozen dough breads onthe one hand, and commercial partially baked breads on the other hand, were due to their differentformulations. Concerning bread physical properties, the recipe also influenced bread crust/crumb ratioand density. Moreover, adding a partial baking stage to the process led to breads with a more compactcrumb.

� 2008 Elsevier Ltd. All rights reserved.

1. Introduction

For centuries, baked cereal products have been widely con-sumed throughout the world. Among these, bread is the mostpopular because of its nutritional quality and its sensorial andtextural properties (Patel et al., 2005). However, conventional breadis characterised by a relatively short shelf-life, resulting fromphysicochemical changes that lead to a loss of freshness with anincrease in crumb hardness and an alteration of its organolepticquality (Baik and Chinachoti, 2000; Barcenas et al., 2003). Due to anincreasing consumer demand for fresh bread, new technologies

PME, head-space solid phaset significant differences; MS,: Wiley 6; NS, not significant;

, recipe 2; R3, recipe 3; R1C,baked frozen process; R1FD,dough process; R1PB, recipe

ked process; R3PBF, recipe 3/ute; STD, identification based

x: þ33 2 51 78 55 20.visenet).

All rights reserved.

have been developed to avoid these undesirable changes and toextend bread shelf-life (Fik and Surowka, 2002). One methodinvolves the addition of particular components, such as emulsifiersand hydrocolloids or proteins and enzyme preparations, to therecipe (Barcenas et al., 2003; Fik and Surowka, 2002). Anothermethod applied to prevent bread staling consists in modifying theprocess conditions. The major objective is to offer consumers freshbread at any time of the day, thus excluding these aging problems.Among these processes, an efficient technique is to add a freezingstage after the final baking, which leads to a fully baked frozenbread (Fik and Surowka, 2002). Freezing temperatures can also beapplied to the dough, interrupting the bread-making beforeproofing (Barcenas et al., 2003; Patel et al., 2005; Rouille et al.,2000). This corresponds to the frozen dough technology, also calledgreen dough. A first partial baking stage can also be added to theprocess, followed by refrigeration and storage at room temperature,or by storage in freezing conditions. These technologies producepartially baked bread and partially baked frozen bread, respectively(Barcenas et al., 2003; Vulicevic et al., 2004). These different breadsare important products in terms of innovation and feasibility asthey correspond to processes that reduce cereal waste, processspace and baking equipment (Patel et al., 2005). Nowadays, they arewidely commercialised since they offer fresh baked bread with

P. Poinot et al. / Journal of Cereal Science 48 (2008) 686–697 687

a simple final baking stage at retail outlets or in householdconditions.

Because of the development of these new technologies, anunderstanding of the influence of flour parameters, recipe in-gredients, as well as the bread-making process, has become es-sential to improve or maintain bread organoleptic characteristics(Cayot, 2007). Indeed, bread characteristics are largely influencedby the process applied and the recipe (Pozo-Bayon et al., 2006).Baardseth et al. (2000) demonstrated that a change in themanufacturing process (traditional French process versus in-dustrially modified process) produced variations in the overallsensory quality of French baguettes. Flour quality also affectedFrench baguette quality. Many studies were then carried out toinvestigate the effect of a frozen stage or partial baking on breadphysical and sensory qualities (Fik and Surowka, 2002; Patelet al., 2005; Rouille et al., 2000). They essentially aimed to definethe optimal freezing conditions for frozen bread dough (Patelet al., 2005), or the optimal partial baking and freezing condi-tions for partially baked bread (Barcenas and Rosell, 2006; Fikand Surowka, 2002; Vulicevic et al., 2004), in order to deliverbread to consumers with sensory qualities close to those of freshbread.

Although the sensory and physical qualities of frozen doughbread and partially baked bread (frozen or not) have been widelyanalysed (Barcenas and Rosell, 2006; Barcenas et al., 2003; Fikand Surowka, 2002; Patel et al., 2005; Rouille et al., 2000;Vulicevic et al., 2004), only a few studies have dealt with theimpact of both their process and their formulation on the releaseof volatile compounds. Within this context, Zehentbauer andGrosch (1998a,b) studied the release of crust volatile compoundsfrom two French baguettes differing in their amount of yeast andtheir dough-making process. They showed that a modification ofthe process and the formulation parameters involved changes inthe amount of volatile compounds released, which led to dif-ferent crust odorant perceptions. However, overall bread flavouris the result of many interactions between volatile and non-volatile bread compounds, present both in the crust and thecrumb. Thus, changes in the bread-making process and recipecould lead to a modification of crust and crumb physical prop-erties, which could be linked to a change in overall odorantperception due to the formation and release of different volatilecompounds.

This work consisted of two successive sets of experiments. Thefirst aimed to analyse the odorant perception, volatile compoundrelease and physical characteristics of five commercial breads.These were based on different recipes (ingredients were added indifferent quantities in the formula) and used different processingconditions: conventional bread (or ‘‘scratch baking’’), fully bakedfrozen bread, frozen dough bread, partially baked bread andpartially baked frozen bread. As these breads differed both in theirrecipes and their processes, complementary experiments werethen carried out to investigate the reasons for their aromatic andphysical distinction. During these experiments, conventional,frozen dough and partially baked breads prepared using the samerecipe were characterised. The odorant perception, aromaticcomposition and physical properties of the breads studied duringthese two series of experiments were then linked to determine theimpact of process and formulation on bread organolepticcharacteristics.

2. Materials and methods

2.1. Raw materials

Type 55 wheat flour was purchased from Moulins SouffletPantin (Pornic, France). Flour was characterised by 13.7% moisture

(AACC method 44-15A), 10.6% protein (ICC Standard method no.116/1), 0.5% ash (AACC method 08-01), 402 s Hagberg fallingnumber (AACC method 56-81B and ICC method no.107/1), 38 sZeleny index evaluated by the sedimentation test developed byZeleny. Salt was supplied by Esco France S.A. (Levallois-Perret,France) and improver (83.2% dry flour, 15% Multec datem HP20, 1%alfa-amylase and xylanase, 0.8% ascorbic acid) was purchased fromPuratos (Groot-Bijgaarden, Belgium). Fresh compressed yeast wassupplied by Michard SAS (Theix, France).

2.2. Bread preparation

Fig. 1 shows the flow diagram for the five commercial bread-makings studied. The recipes and processes of these five breadswere provided by partners of the European project FOOD-2006-36302 EU-FRESH BAKE. Three different recipes were followed (R1,R2 and R3), which differed in their quantities of yeast, water andimprover. In these recipes, water quantity had previously beenadapted to produce a homogenous dough hydration. Conven-tional bread (R1C) and fully baked frozen bread (R1FBF) werebased on the same recipe (R1), while partially baked bread(R3PB) and partially baked frozen bread (R3PBF) were based onrecipe R3. Frozen dough bread (R2FD) was based on a differentformula (R2).

Fig. 2 shows the flow diagram for the study of breads based onthe same recipe and different processes. The formula used for thesethree breads corresponded to the formulation of the commercialconventional and the fully baked frozen breads (R1) (Fig. 1). Theconventional (R1C), frozen dough (R1FD) and partially baked(R1PB) processes were studied to reveal the impact of the recipeand the process on bread characteristics.

Dough was mixed in an SP10 spiral mixer (VMI, Montaigu,France). At the end of mixing, the dough temperature was mea-sured and found to be between 17 �C and 18 �C. The dough wasflattened with a roller to obtain a round, symmetrical andhomogenous thick sheet. It was then divided into 30 samples, ballshaping about 70 g using a dividing–moulding machine (Bongard,Holtzheim, France). For fermentation, samples were placed ina proofing cabinet (Panimatic, Souppes s/Loing, France). Partialbaking was carried out in a ventilated oven with steam injection atthe beginning of baking (Sofinor, Bois-Grenier, France). At the endof partial baking, the bread core temperature was checked. It was100 �C. The final baking was done in a static sole oven (MIWECondo, Arnstein, Germany) without forced convection of hot andmoist air. The temperature in the final baked bread core wasverified and found to be between 98 �C and 103 �C. Freezing offully baked frozen breads (R1FBF), frozen dough breads (R1FD andR2FD) and partially baked frozen breads (R3PBF) was carried outin a freezer (Matal, France) at �30 �C for 30 min. Bread sampleswere placed directly in the freezer without previous packing. Aftertheir freezing stage, fully baked frozen breads (R1FBF) werethawed at room temperature for 60 min before measurements.Likewise, frozen dough breads (R1FD and R2FD) were thawed for60 min at room temperature and then placed in the proofingcabinet for fermentation. Partially baked frozen breads (R3PBF)were thawed at room temperature for 10 min before their finalbaking.

To control the final baking stage, the coloration of bread crustwas followed. Indeed, bread crusts had to reach the same color-ation as that of a bread reference. After the final baking, breadswere cooled for 30 min at room temperature. Bread crust color-ation was measured by a Minolta CR300 colorimeter (Carrieres-sur-Seine, France) which displayed the L*C*h colour parametersfor every sample. Breads were placed on their base and fourmeasurements were made at four different locations on the top ofthe breads. The difference in coloration between breads and the

Recipe 1 (noted R1)

2% salt 1% improver

5% fresh yeast 58% water 100% flour

Mixing

2 min 100 rpm7 min 200 rpm

Bulk fermentation

15 min covered withplastic at roomtemperature

Recipe 2 (noted R2)

2% salt3% improver

5% fresh yeast56% water

100% flour

Mixing

2 min 100 rpm7 min 200 rpm

Recipe 3 (noted R3)

2% salt1% improver

2% fresh yeast52% water100% flour

Mixing

2 min 100 rpm 7 min 200 rpm

Conventional bread

(noted R1C)

Frozen dough bread

(noted R2FD)

Cooling

30 min at room temperature

Final baking

20 min at 230°C with 0,5 L steam at start baking

Cooling

30 min at roomtemperature

Freezing

30 min at -30°C

Defrosting

60 min at roomtemperature

Fully baked frozen bread

(noted R1FBF)

Final baking

12 min at 230°Cwithout steam

Partially baked bread

(noted R3PB)

Freezing

30 min at -30°C

Defrosting

10 min at roomtemperature

Final baking

12 min at 230°Cwithout steam

Partially baked

frozen bread

(noted R3PBF)

Defrosting

60 min at room temperature

Moulding

Scaling 2100g for 30 pieces ball shaping

Dividing / moulding

Flatten the dough with roller. Dividing and moulding into 30 pieces

Freezing

30 min at -30°C Fermentation

105 min at 30°C and 95 RH

Partial baking

3 min at 190°C with 0,5 L steam at start bakingthen 14 min at 165°C

Fermentation

60 min at 35°C and 95 RH

Resting

10 min covered with plastic at room temperature

Fig. 1. Flow diagram illustrating the formulation steps of the five commercial breads differing by their recipes and processes. R1C: recipe 1/conventional process; R1FBF: recipe 1/fully baked frozen process; R2FD: recipe 2/frozen dough process; R3PB: recipe 3/partially baked process; R3PBF: recipe 3/partially baked frozen process.

P. Poinot et al. / Journal of Cereal Science 48 (2008) 686–697688

Cooling

30 min at room temperature

Final baking

12 min at 230°C withoutsteam

Defrosting

60 min at roomtemperature

Dividing / moulding

Flatten the dough withroller. Dividing andmoulding into 30

pieces

Freezing

30 min at -30°C

Partial baking

3 min at 190°C with 0,5 Lsteam at start baking

then 14 min at 165°C

Fermentation

60 min at 35°C and 95 RH

Final baking

20 min at 230°C with 0,5 L steam at start baking

Conventional bread

(noted R1C)

Partially baked bread

(noted R1PB)

Frozen dough bread

(noted R1FD)

Bulk fermentation

15 min covered withplastic at roomtemperature

Recipe 1 (noted R1)

2% salt1% improver

5% fresh yeast58% water100% flour

Mixing

2 min 100 rpm7 min 200 rpm

Resting

10 min covered withplastic at roomtemperature

Moulding

Scaling 2100g for 30pieces ball shaping

Fig. 2. Flow diagram illustrating the formulation steps of the three breads based on the same recipe but differing by their processes. R1C: recipe 1/conventional process; R1FD:recipe 1/frozen dough process; R1PB: recipe 1/partially baked process.

P. Poinot et al. / Journal of Cereal Science 48 (2008) 686–697 689

P. Poinot et al. / Journal of Cereal Science 48 (2008) 686–697690

reference (DE) was evaluated according to the followingequations:

b* ¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi���C*�2��

tan h2����

1þ ðtan hÞ2��s

a*¼ b*=ðtan hÞ

DE ¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi��Lsample crust � Lbread reference crust

�2þ�

a*sample crust � a*

bread reference crust

�2þ�

b*sample crust � b*

bread reference crust

�2s

where L is the clearness, C* the saturation, h the shade angle, and a*

and b* are coloration coordinates.The results showed that the five commercial breads were all

baked similarly (3.75<DE< 5.04). The same result was obtainedfor breads produced from the same recipe but different processes(6.56<DE< 7.14). This confirmed that the final baking was re-producible between all bread-makings. Thus, bread characteristics(density, crust/crumb ratio, texture and odour) were due only totheir formulation and their bread-making process.

During the whole study, 10 breads per baking batch were usedfor the overall measurements each day: two breads were dedicatedto texture analysis, four breads were used for the density and crust/crumb ratio measurements, and the last four breads were used forthe volatile compound extraction and the sensory analysis. More-over, during the study of the five commercial breads, two differentbread-makings were carried out each day.

2.3. Instrumental texture analysis

Crumb texture was determined by a texture analyser Instron5544 (Guyancourt, France) provided with the Merlin Instron Soft-ware and equipped with a 35 mm diameter cylindrical probe, largerthan the size of a bread crumb. Measurements were performed ata constant room temperature. Slices of 25 mm thickness werecompressed to 40% of their original height in a simple compressiontest, at a cross-head speed of 100 mm min�1. The maximum forceapplied to compress slices was noted. The measurement of thecrumb texture of two breads per baking batch was performed 3 hafter the final baking. Eight texture measurements were thenrecorded for all bread-making conditions.

2.4. Bread density

After 3 h cooling at room temperature, the density of four breadswas determined. The measurement consisted in weighing breadsand in assessing their volume using a rapeseed displacementmethod (Rouille et al., 2000). The mass/volume ratio was thencalculated. As each bread-making process was carried out fourtimes, 16 measurements of bread density were obtained for eachtype of bread-making.

2.5. Crust/crumb ratio

The crust/crumb ratio of four breads was assessed 3 h afterbaking. Breads were first weighed. Then, bread crumb was removeduniformly from the crust by hand. The separation between crumband crust was determined by the fact that crumb can be removedfrom the crust with a very low force. The mass of the remainingcrust was measured. The crust to crumb ratio was then calculated

from the corresponding mass ratio. This measurement was re-peated four times, thus 16 measurements were performed for eachbread-making condition.

2.6. Crumb moisture loss after the final baking

Bread crumb moisture loss was assessed 3 h after the finalbaking. A crumb slice of 2 g was taken from the bread centre. It was

then dried at 100 �C for 24 h. The moisture loss was calculated bythe weight loss as a percentage of the initial weight of the sample.Four measurements of bread crumb moisture loss were obtainedfor each bread-making process.

2.7. Sensory analysis

Triangular tests were carried out to assess odorant differencesbetween breads corresponding to two different bread-makings.During each set of experiments, a factorial design was performed tocompare the odour of breads obtained by a specific bread-makingprocess with the odour of breads obtained by another process.Thus, the five commercial breads were compared between eachother for their odour. The odour of the three breads based on thesame recipe but different processes was also compared in anotherset of experiments.

Four breads per baking batch were used for each sample prep-aration. Thirty minutes after the final baking, breads were entirelycrushed and homogenised. Then 6 g of these crushed breads wasput in 100 mL flasks, which were then hermetically closed andidentified by a three-number code.

Sessions were carried out in a specific sensory room, 1 h 30 minafter sample preparation. The panellists were isolated from eachother in cubicles. For each triangular test, samples were presentedto 30 naive judges, aged from 20 to 50 years. During a session,judges were asked to smell three samples. Among these, twocontained crushed bread from the same bread-making while thethird sample contained crushed bread from a different bread-making. They had to identify which sample was different from theother two. Panellists were allowed to smell samples only once andthey were forced to answer the question (forced-choice method).Samples were presented to the judges in a random order.

A significant odorant difference for a risk of 5% between twobreads was obtained when it was perceived by more than 15 judges(AFNOR, 2002).

2.8. Bread volatile compound analysis

2.8.1. ChemicalsAlkanes from octane to nonadecane, used to calculate volatile

compound retention indexes, came from Aldrich (Steinheim, Ger-many) except for octane, hexadecane, octadecane and nonadecane,which were purchased from Sigma (Saint Louis, USA), pentadecanefrom Fluka (Steinheim, Germany) and hexane from Merck (Darm-stadt, Germany). 1-Butanol, used as an internal standard, wassupplied by Aldrich (Steinheim, Germany). Standards were alsoemployed for compound identification. They were purchased fromAldrich (Steinheim, Germany), except for 2-butanone, 1-propanol,2,3-butanediol, and isobutyric acid, which were from Fluka

Table 1ANOVA to determine the effect of the bread-making on bread physical character-istics: crumb hardness, density, crust/crumb ratio and crumb moisture lost after 24 hat 100 �C

Physicalmeasurement

p-Value(level of 0.05)

Effect of the bread-makingon the physical propertiesof the five commercial breads

Crumb texture 0.0141Density 0.0000Crust/crumb ratio 0.0000Crumb moisture lossafter 24 h at 100 �C

0.7966

Effect of the bread-makingon the physical propertiesof the three breads basedon the same recipeand different processes

Crumb texture 0.0396Density 0.9238Crust/crumb ratio 0.9948Crumb moisture lossafter 24 h at 100 �C

0.1986

P. Poinot et al. / Journal of Cereal Science 48 (2008) 686–697 691

(Steinheim, Germany), 2,3-pentanedione from Safc (Steinheim,Germany), and acetic acid from Panreac (Barcelona, Spain).

2.8.2. Bread volatile compound extractionFour breads per baking batch were used to carry out the

experiments. The HS-SPME (Head-Space Solid Phase Micro-Extraction) conditions (fibre type, extraction time and extractiontemperature) applied to extract bread volatile compounds hadbeen previously optimised to ensure that extracts were represen-tative of the odour of the bread from which they came (Poinot et al.,2007). Thirty minutes after baking, breads were entirely crushed(crust and crumb). Six grams of homogenised crushed bread wasplaced in a 125 mL flask with a magnetic stirring bar and 5 mL ofinternal standard. The flask was then sealed with a silicone septaand immersed in a water bath at 35 �C. After 5 min equilibrium,a 75 mm Carboxen/Polydimethylsiloxane fibre was exposed to thesample head-space for 30 min. During the extraction, the samplewas continuously shaken with a magnetic stirring bar. At the end ofthe extraction time, the fibre was inserted into a Gas Chromato-graph injector port for volatile thermal desorption during 5 min. Aseach bread-making process was performed four times, four volatilecompound extractions were carried out for each bread type.

2.8.3. Gas chromatography and mass spectrometry analysisThe identification and quantification of volatile compounds

was carried out with a Gas Chromatograph Agilent 6890N coupledto a Flame Ionization Detector, a quadrupole Mass DetectorAgilent 5973 Network. Volatile compounds were separated ona DB-WAX polar capillary column 30 m� 0.32 mm, 0.5 mm filmthickness (J&W Scientific, Folsom, USA). Helium was used as thecarrier gas with a flow rate of 2 mL min�1 (pressure: 62.4 kPa). Theinjector temperature was set at 260 �C in split 1:1 mode for 2 min.It was then put in splitless mode until the end of the run time. Theoven temperature program was held for 2 min at 45 �C, thenincreased by 5 �C min�1 to 50 �C, by 0.5 �C min�1 to 51 �C, by8 �C min�1 to 170 �C, and then by 18 �C min�1 to 230 �C. Thetemperature was then held at 230 �C for 8 min (for a total runtime of 31.20 min).

The mass detector was at 250 �C and operated in scan mode,with electronic impact ionization (ionization energy 70 eV), whilea mass range of 33–300 amu and a scan rate of 2.72 scans s�1 wereused to detect the ions formed. Compound identification was basedon a comparison of linear retention indices (LRI), mass spectra(comparison with standard MS spectra databases: Wiley 6), andinjection of standards. The quantification was performed using 1-butanol as the added standard. The concentrations of volatilecompounds were expressed in microgram equivalents of 1-butanolper gram of bread.

2.9. Statistical analysis

Instrumental data were subjected to Analysis of Variance(ANOVA) using Statgraphics Plus 5.1 Software (Manugistics, Rock-ville, Maryland, USA). One-way ANOVA and possible significantdifferences between the physical response values were evaluatedby Least Significant Differences (LSD) multiple comparison testswith a confidence level of 95%.

One-way ANOVA and LSD tests were then performed on theamount of each volatile compound trapped in all bread extractswith a confidence level of 95%. Another one-way ANOVA was per-formed to show the effect of the bread-making on the total quantityof volatile compounds released according to their origin.

A Principal Component Analysis (PCA) using Uniwin Plus 5.1Software (Sigma Plus, Paris, France) was done on the quantities ofvolatile compounds extracted from the five commercial breads todifferentiate them.

3. Results

3.1. Bread physical characteristics

The difference in crumb texture of the five commercial breads isshown in Table 1 and Fig. 3. A significant difference was determinedat a confidence level of 95% between commercial bread crumbtexture according to the bread-making process (p-value: 0.0141).The LSD test revealed that the commercial breads could be differ-entiated into three groups. The force applied to compress conven-tional and frozen dough breads was significantly lower compared tothat applied to partially baked breads (frozen or not). The crumb ofcommercial conventional bread had an intermediate resistance tocompression. Commercial frozen dough bread was characterised bythe softest crumb, while commercial partially baked breads (frozenor not) were characterised by the most compact crumb. To explainthe physical differences observed between these five bread-makingprocesses, breads formulated from the same recipe but by differentprocesses were then analysed (Fig. 2). There was a significant effectof the process on crumb texture (Table 1). Indeed, partial bakingwas responsible for a significantly harder bread crumb compared toconventional and dough freezing treatments (Fig. 3).

Concerning density and crust/crumb ratio, a significant effect ofthe bread-making on commercial breads was identified (p-values:0%) (Table 1). In contrast, their crumb moisture loss did not differ(p-value: 0.7966). Commercial breads could be separated into threeand four different LSD groups according to their density and theircrust/crumb ratio, respectively (Fig. 3). Conventional bread wascharacterised by the lowest density and the highest crust/crumbratio. The density of fully baked frozen bread was significantlyhigher and it was also characterised by a significantly lower crust/crumb ratio. Like conventional bread, frozen dough bread wasdefined by the lowest density, and it was also characterised by anintermediate crust/crumb ratio. Partially baked bread and partiallybaked frozen bread could be gathered in the same group accordingto their density and their crust/crumb ratio. These two breads werecharacterised by the significantly highest density and the smallestcrust/crumb ratio. The density and crust/crumb ratio differencesobserved between the commercial breads were further in-vestigated by the analysis of breads based on the same recipe butfrom different processes. It was thus demonstrated that neitherdough freezing nor partial baking had an effect on bread densityand crust/crumb ratio (Table 1, Fig. 3).

3.2. Characterisation of bread odorant perceptions

Triangular tests with a confidence level of 95% were performedto find out if there were odorant differences between breads(Table 2). Commercial conventional, fully baked frozen and frozendough breads were characterised by a similar odour. On the

Crumb texture : Mean of the maximal

compressive force (Newton) Density (10

1 Kg.L

-1) Crust/crumb ratio

Physical

properties of the

five commercial

breads

0

2

4

6

8

R1C R1FBF R2FD R3PB R3PBF R1C R1FBF R2FD R3PB R3PBF R1C R1FBF R2FD R3PB R3PBF0

1

2

3

4

0

1

2

3

4

Physical

properties of

the three breads

based on the

same recipe and

different

processes

0

1

2

3

R1C R1FD R1PB R1C R1FD R1PB R1C R1FD R1PB0

1

2

3

4

0

1

2

3

4

b,c

a,b

c

aa

b

cc

aa

e e e

e

ff

a b

c

dd

ee

e

Fig. 3. Comparison of bread physical characteristics. R1C: recipe 1/conventional process; R1FBF: recipe 1/fully baked frozen process; R2FD: recipe 2/frozen dough process; R3PB:recipe 3/partially baked process; R3PBF: recipe 3/partially baked frozen process; R1FD: recipe 1/frozen dough process; R1PB: recipe 1/partially baked process. a,b,c,d/e,f: LSD resultsat a confidence level of 95%. Bread-makings noted with the same letter are not significantly different at a confidence level of 95%.

P. Poinot et al. / Journal of Cereal Science 48 (2008) 686–697692

contrary, they were perceived differently compared to commercialpartially baked and partially baked frozen breads. Moreover, frozendough bread had the same odour as partially baked bread. Nosignificant odorant difference was assessed between breads withthe same formula and different processes.

First, to understand the odorant differences perceived betweenthe five commercial breads, their volatile extracts were analysed.Volatile compound extraction was performed four times for eachbread-making. The identification and quantification of volatilecompounds trapped was then carried out (Table 3). Thus, 46 dif-ferent volatile compounds were identified in the whole of thebread-makings. A PCA was performed on the quantity of volatilecompounds identified for each bread-making. Figs. 4 and 5 displaythe configuration plots obtained by PCA. The first three principaldimensions explained 67.3% of the total variance. Each dimensionwas correlated with different bread volatile compounds. The firstdimension (which explained 46.5% of the total variance) mainlyopposed alcohols, such as ethanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 1-pentanol, and 1-hexanol, resulting from fermentation

Table 2Results of the triangular tests performed to compare the odour of the breadsanalysed

Comparison of bread odour perception

Difference in odourperceptionof the fivecommercialbreads

R1C R1FBF R2FD R3PB R3PBFR1C NS NS � �R1FBF NS � �R2FD NS �R3PB �R3PBF

Comparison of bread odour perception

Difference in odourperception of thethree breads basedon the same recipeand different processes

R1C R1FD R1PBR1C NS NSR1FD NSR1PB

R1C: recipe 1/conventional process; R1FBF: recipe 1/fully baked frozen process;R2FD: recipe 2/frozen dough process; R3PB: recipe 3/partially baked process;R3PBF: recipe 3/partially baked frozen process; R1FD: recipe 1/frozen dough pro-cess; R1PB: recipe 1/partially baked process. Results are given for at a confidencelevel of 95%; NS: not significant; �: significant.

and/or lipid oxidation, to Maillard volatile products, such as 2-methylpropanal, 2-methylfuran, 2-acetylfuran, 3-methylbutanal,2,3-pentanedione, 1-methylpyrrole, 5-methyl-2-furfural, 2-meth-ylpyrazine, 2,3-dimethylpyrazine, pyrazine, 2-ethyl-5-methylpyr-azine, 2-ethyl-6-methylpyrazine, pyrrole, furfuryl alcohol andfermentative acids. The second dimension was negatively corre-lated to fermentative compounds, such as 2-methyl-1-propanol, 3-hydroxy-2-butanone and benzaldehyde. The third dimension waspositively correlated to 2-pentylfuran and benzaldehyde.

The representation of the five commercial breads revealed thatmost of the four extracts of conventional bread, fully baked frozenbread and frozen dough bread were opposed on the first dimensionto the extract repetitions of partially baked bread and partiallybaked frozen bread, which had a close volatile composition. TheLSD test performed on the total quantities of volatile compoundsresulting from the Maillard reaction, lipid oxidation and fermen-tation (Table 4) revealed that commercial conventional bread, fullybaked frozen bread and frozen dough bread were composed ofsignificantly higher quantities of Maillard compounds. Commercialpartially baked frozen bread extracts were characterised by sig-nificantly lower amounts of these compounds, while they con-tained significantly more alcoholic compounds coming from lipidoxidation and/or fermentation. Commercial partially baked breadcontained intermediate amounts of lipid oxidation and fermenta-tive compounds.

Secondly, volatile extracts of breads produced from the samerecipe but by different processes were analysed to explain thearomatic differences perceived between the commercial breads.The compounds identified in these bread extracts corresponded tothe volatile compounds characterised in the commercial breads(Table 3). An ANOVA was carried out to determine whether therewas a significant difference in each quantity of volatile compounddepending on the process applied. The results revealed that thequantity of 42 of the volatile compounds was not significantlydifferent at a confidence level of 95% (data not shown). A significantbread-making process effect was only seen on amounts of ethylacetate, 2-methyl-1-propanol, 2-methyl-1-butanol and 3-methyl-1-butanol. The quantity of ethyl acetate and 2-methyl-1-butanolwas significantly lower in partially baked breads. A significantlyhigher quantity of 2-methyl-1-propanol was identified in frozen

Table 3Volatile compounds extracted by HS-SPME from the bread extracts analysed

Volatile compound LRI Identification Origin

2-Methylpropanal 821 LRI, MS, STD Maillard reactionj,k

2-Methylfuran 874 LRI, MS, STD Maillard reactionj,i

Ethyl acetate 903 LRI, MS, STD Fermentationd,g

2-Butanone 916 LRI, MS, STD Maillard reactiona,j

2-Methylbutanal 923 LRI, MS, STD Maillard reactionj,k

3-Methylbutanal 899 LRI, MS, STD Maillard reactionj,k

Ethanol 945 LRI, MS, STD Fermentationd, g

2,3-Butanedione 985 LRI, MS, STD Fermentationd,g;Maillard reactionj

1-Propanol 1050 LRI, MS, STD Fermentationg,j;lipid oxidatione

2,3-Pentanedione 1073 LRI, MS, STD Maillard reactiona,j,k

Hexanal 1105 LRI, MS, STD Lipid oxidationc,d,e

2-Methyl-1-propanol 1116 LRI, MS, STD Fermentationd,g

1-Methylpyrrole 1162 LRI, MS, STD Maillard reactiona,j

2-Pentylfuran 1227 LRI, MS, STD Maillard reactiona,j;lipid oxidatione

2-Methyl-1-butanol 1245 LRI, MS, STD Fermentationd,g

3-Methyl-1-butanol 1254 LRI, MS, STD Fermentationc,d,f,g

Pyrazine 1262 LRI, MS, STD Maillard reactiona,j

1-Pentanol 1286 LRI, MS, STD Lipid oxidationd,e

Dihydro-2-methyl-3(2H)-furanone

1288 LRI, MS, STD Maillard reactiona,j

2-Methylpyrazine 1309 LRI, MS, STD Maillard reactiona,d,j

3-Hydroxy-2-butanone 1323 LRI, MS, STD Fermentationd,g

Hydroxyacetone 1333 LRI, MS, STD Undetermined2-Ethylpyrazine 1377 LRI, MS, STD Maillard reactiona,j

2,5-Dimethylpyrazine 1375 LRI, MS, STD Maillard reactiona,j

1-Hexanol 1389 LRI, MS, STD Lipid oxidationd,e

2,3-Dimethylpyrazine 1397 LRI, MS, STD Maillard reactiona,j

2-Ethyl-6-methylpyrazine 1420 LRI, MS Maillard reactiona,j

2-Ethyl-5-methylpyrazine 1428 LRI, MS Maillard reactiona,j

2-Ethyl-3-methylpyrazine 1441 LRI, MS, STD Maillard reactionj

3-Furfural 1454 LRI, MS Maillard reactionj

1-Octen-3-ol 1469 LRI, MS, STD Lipid oxidatione

Acetic acid 1466 LRI, MS, STD Fermentationd,g,h

Furfural 1516 LRI, MS, STD Maillard reactiona,d,j;fermentationc

Pyrrole 1518 LRI, MS, STD Maillard reactiona,j

2-Acetylfuran 1556 LRI, MS, STD Maillard reactiond,k

Propionic acid 1554 LRI, MS, STD Fermentationb,h

Benzaldehyde 1578 LRI, MS, STD Fermentationd;lipid oxidatione,i

2,3-Butanediol 1592–1636 LRI, MS, STD UndeterminedIsobutyric acid 1582 LRI, MS, STD Fermentationb,j

5-Methyl-2-furfural 1642 LRI, MS, STD Maillard reactiona,d,j

Butyric acid 1652 LRI, MS, STD Fermentationb

Isovaleric acid 1691 LRI, MS, STD Fermentationb,j

Furfuryl alcohol 1705 LRI, MS, STD Maillard reactiond,j

Hexanoic acid 1884 LRI, MS, STD Fermentationb;lipid oxidatione,j

Phenylethyl alcohol 1895 LRI, MS, STD Fermentationc,d,f

Maltol 1891 LRI, MS, STD Maillard reactionj

LRI: linear retention index on DB-WAX column; MS: identification based on stan-dard MS spectra databases: Wiley 6; STD: identification based on standard injection;compounds written in italic were tentative identifications.

a Aubry et al., 1997.b Daigle et al., 1999.c Frasse et al., 1992.d Galey et al., 1994.e Grosch, 1987.f Grosch and Schieberle, 1997.g Hansen and Schieberle, 2005.h Javanainen and Linko, 1993.i Oruna-Concha et al., 2002.j Pozo-Bayon et al., 2006.k Rychlik and Grosch, 1996.

P. Poinot et al. / Journal of Cereal Science 48 (2008) 686–697 693

dough breads. Finally, the amount of 3-methyl-1-butanol was sig-nificantly lower in partially baked breads than in frozen doughbreads. Conventional breads contained an intermediate amount ofthis volatile compound. To complete these results, an ANOVA wasperformed on the total quantity of the volatile compounds groupedin terms of their origin (Table 4). A significant effect of the process

on the total amount of volatile compounds was observed. Com-pounds resulting from the Maillard reaction and lipid oxidationwere released in similar quantities whichever process was applied.Partially baked breads were characterised by a significantly loweramount of fermentative compounds than in conventional and fro-zen dough breads.

4. Discussion

4.1. Bread physical characteristics

In order to highlight the influence of the formula and the pro-cess on bread physical characteristics, an analysis of bread crumbtexture, as well as the measurement of density, crust/crumb ratioand crumb moisture loss, was carried out.

As conventional bread (R1C) and fully baked frozen bread(R1FBF) were based on the same recipe, the physical differencesidentified between them may be linked to the freezing–thawingstage that distinguished them. Indeed, adding a freezing–thawingstage after the final baking in the conventional process led tobreads that were characterised by a relatively harder and morecompact crumb. This may be due to the difference in moisturecontent between the crust and the crumb portions in conventionalbread (Cauvain, 1998). Crust and crumb may thus expand andcontract at different rates during the freezing and thawing cycles,which leads to a detachment of the crust from the body of theproduct (Cauvain, 1998), as well as crumb contraction (Ribotta andLe Bail, 2007). Crumb contraction could be due to the freezing itself,during which water is removed from the protein–starch–watermatrix in the form of ice. This leads to an increase in the matrixcontraction and then a more compact crumb after thawing (Ribottaand Le Bail, 2007). Another explanation of this more compactcrumb could be that during chilling, the gas phase and possibly thedough macromolecules could be compressed (Ribotta and Le Bail,2007).

As frozen dough bread was characterised by similar physicalcharacteristics to conventional bread when they were based on thesame recipe (R1), it may be thought that a freezing stage (not fol-lowed by prolonged frozen storage) has no effect on these prop-erties when they are measured rapidly after the final baking.Indeed, in our study, the physical properties of all the breads weremeasured 3 h after their final baking. As previously reported byRibotta et al. (2001), bread crumb hardness of conventional breadswas the same as that of frozen dough breads when it was measuredrapidly after their final baking. Moreover, frozen dough breads werefrozen for only 30 min. This time may not have been sufficient toinduce physical modifications in bread crumb structure. On thecontrary, prolonged storage would be expected to induce a de-terioration in bread quality (lower loaf volume, longer fermentationtime, increased proofing time and increased bread staling) as wasreported by Phimolsiripol et al. (2008). This deterioration is mainlydue to an alteration of dough properties, which results from a de-crease in both yeast viability and activity. A decrease in CO2 pro-duction and a release of reducing substances, such as glutathione,from yeasts could lead to dough weakening (Phimolsiripol et al.,2008; Ribotta et al., 2001). Frozen storage also leads to damage ofthe three-dimensional gluten protein network with a reduction ingluten cross-linking, which induces poor gas retention ability(Phimolsiripol et al., 2008; Rouille et al., 2000). Modification of thewater-binding capacity of dough constituents also alters breadtextural properties (Ribotta et al., 2001; Rouille et al., 2000).

A freezing–thawing stage added to the commercial partiallybaked process had no effect on bread crumb texture, crust/crumbratio, density and crumb water loss. Like in frozen dough breads,this result could be explained by the rapid freezing (30 min) of thepartially baked breads. Indeed, as previously demonstrated by

2-Methylpropanal

5-Methyl-2-furfural

2-Acetylfuran

Pyrazine

2-Methylpyrazine1-Methylpyrolle

3-Methylbutanal

2-Methylfuran

2-Ethyl-5-methylpyrazineMaltol

2,3-PentanedionePyrolle

2-Ethylpyrazine

2,3-Dimethylpyrazine2-Ethyl-3-methylpyrazine

HydroxyacetoneFurfuryl alcohol

Hexanoic acidIsobutyric acid

Dihydro-2-methyl-3(2H)-furanone

2-Ehyl-6-methylpyrazine3-Furaldéhyde

Butyric acid

Propionic acid2,5-Dimethylpyrazine

Isovaleric acid2,3-Butanedione

Acetic acid

2,3-ButanediolEthyl acetate

Furfural

2-Butanone

3-Hydroxy-2-butanone

Benzaldéhyde

Hexanal

Phenylethyl alcohol

2-Methylbutanal

2-Pentlyfuran

2-Methyl-1-propanol

HexanolPentanol

Ethanol 3-Methyl-1-butanol

Propanol2-Methyl-1-butanol

1-Octen-3-ol

PC 1 - 46.5%

PC

2

- 1

0.7

%

R2FD1

R1FBF1R2FD

2

R2FD3

R1FBF3

R1FBF4

R1FBF4

R2FD4

R3PBF1

R3PBF2

R3PB2

R3PBF4

R3PB4

R3PB3

R3PBF3

R3PB1

R1C2

R1C1

R1C1

R1C4

-10

0

10

-10 0 10PC 1 - 46.5%

PC

2 - 10.7%

Fig. 4. Correlation and commercial bread extract plots based on the quantity of volatile compounds extracted from them in the first two dimensions. R1C: recipe 1/conventionalprocess; R1FBF: recipe 1/fully baked frozen process; R2FD: recipe 2/frozen dough process; R3PB: recipe 3/partially baked process; R3PBF: recipe 3/partially baked frozen process. 1/2/3/4: Number of repetition.

P. Poinot et al. / Journal of Cereal Science 48 (2008) 686–697694

Barcenas and Rosell (2006), partial baking followed by a rapidfreezing stage produces breads with characteristics similar to theconventional one. It may be that ice crystals, which can form inthe crumb during freezing, did not develop sufficiently to damagethe protein network, which would normally lead to an increase incrumb firmness (Barcenas and Rosell, 2006). The deterioration ofstarch granules, caused by ice recrystallisation during frozen stor-age, may also not have been enough to modify the bread structure(Barcenas and Rosell, 2006).

Our study also showed that the high density and the low crust/crumb ratio of commercial partially baked breads (frozen or not)were mainly due to their different formulas (and not to the partial

baking) compared to commercial conventional, fully baked frozenand frozen dough breads. The commercial partially baked breads(frozen or not) contained less yeast in their recipe than the otherthree commercial breads. This lower content would result in a re-duced fermentation activity. CO2 production and release duringproofing were thus lower, reducing crumb expansion. The resultingcrumb was then more compact and the corresponding bread wascharacterised by a higher density.

Finally, bread density and crust/crumb ratio were mainly influ-enced by bread recipe since conventional, frozen dough and par-tially baked breads had a similar density and crust/crumb ratiowhen they were based on the same formula.

2-Methylpropanal

5-Methyl-2-furfural

2-Acetylfuran

Pyrazine

2-Methylpyrazine

1-Methylpyrolle3-Methylbutanal

2-Methylfuran

2-Ethyl-5-methylpyrazine

Maltol

2,3-Pentanedione

Pyrolle

2-Ethylpyrazine

2,3-Dimethylpyrazine

2-Ethyl-3-methylpyrazine

Hydroxyacetone

Furfuryl alcohol

Hexanoic acid

Isobutyric acidDihydro-2-methyl-3(2H)-furanone

2-Ehyl-6-methylpyrazine

3-Furaldéhyde

Butyric acid

Propionic acid

2,5-Dimethylpyrazine

Isovaleric acid

2,3-Butanedione

Acetic acid

2,3-Butanediol

Ethyl acetate

Furfural

2-Butanone

3-Hydroxy-2-butanone

Benzaldéhyde

Hexanal

Phenylethyl alcohol

2-Methylbutanal

2-Pentlyfuran

2-Methyl-1-propanol

Hexanol

Pentanol

Ethanol

3-Methyl-1-butanol

Propanol

2-Methyl-1-butanol 1-Octen-3-ol

PC 1 - 46.5%

PC

3

- 1

0.1

%

R1C4

R1C3

R1C1

R1C2

R3PB1

R3PBF3

R3PB3

R3PB4

R3PBF4 R3PB

2

R3PBF2

R3PBF1

R2FD4

R1FBF4

R1FBF1

R1FBF3

R2FD3

R2FD2

R1FBF2

R2FD1

-10

0

10

-10 0 10PC 1 - 46.5%

PC

3 - 10.1%

Fig. 5. Correlation and commercial bread extract plots based on the quantity of volatile compounds extracted from them in the first and the third dimensions. R1C: recipe 1/conventional process; R1FBF: recipe 1/fully baked frozen process; R2FD: recipe 2/frozen dough process; R3PB: recipe 3/partially baked process; R3PBF: recipe 3/partially bakedfrozen process. 1/2/3/4: Number of repetition.

P. Poinot et al. / Journal of Cereal Science 48 (2008) 686–697 695

4.2. Characterisation of bread odorant perceptions

Triangular tests revealed that a freezing stage had no influenceon bread odour when it preceded or followed the final baking of theconventional process. Thus, the physical modifications identifiedduring analysis and induced by a freezing stage may not be greatenough to have an impact on the final odour perception of bread. Incontrast, adding a freezing stage after partial baking had a signifi-cant influence on bread odorant perception. It was demonstratedthat the difference in odour between commercial conventional,

fully baked frozen and frozen dough breads on the one hand, andcommercial partially baked breads (frozen or not) on the otherhand, was mainly due to their different recipes. In other words, theodorant differences perceived between breads resulted largelyfrom the different quantities of yeast and water in their recipes.

The analysis of bread volatile extracts explained the odorantdifferences highlighted by the triangular tests. As demonstratedpreviously (Poinot et al., 2007), HS-SPME extracts obtained underthese conditions of fibre, temperature and time, were representa-tive of the odour of the corresponding bread. Thus, the fact that

Table 4Comparison of the global quantities of volatile compounds grouped in relation to their origin and extracted by HS-SPME from the different breads analysed

Bread-making Total Maillardreaction*

Lipidoxidation*

Fermentation* Fermentationwithout ethanol

Mean quantity (mg equivalent of 1-butanol g�1 bread)Comparison between

the five differentcommercial breads

R1C 11.49 3.34a 0.17a 8.75a 2.82R1FBF 9.91 2.20a 0.18a 7.93a 2.04R2FD 8.94 2.38a 0.16a 6.79a 2.09R3PB 13.25 0.64b 0.23a,b 12.65a,b 2.65R3PBF 15.76 0.78b 0.29b 15.02b 2.93

Bread-making Total* Maillardreaction

Lipidoxidation

Fermentation*

Mean quantity (mg equivalent of 1-butanol g�1 bread)Comparison between

the three breads basedon the same recipeand different processes

R1C 9.923e 3.80 0.24 6.56e,f

R1FD 10.67e 3.58 0.32 7.47e

R1PB 7.142f 2.59 0.22 4.81f

R1C: recipe 1/conventional process; R1FBF: recipe 1/fully baked frozen process; R2FD: recipe 2/frozen dough process; R3PB: recipe 3/partially baked process; R3PBF: recipe 3/partially baked frozen process; R1FD: recipe 1/frozen dough process; R1PB: recipe 1/partially baked process. *Significant difference in the volatile compounds quantity releasedfrom breads at a confidence level of 95%. a,b/e,f: LSD results at a confidence level of 95%; bread-makings noted with the same letter are not significantly different at a confidencelevel of 95%.

P. Poinot et al. / Journal of Cereal Science 48 (2008) 686–697696

panellists perceived the odour of commercial conventional, fullybaked frozen and frozen dough breads differently from that ofcommercial partially baked and partially baked frozen breads,could be explained by their different composition in volatile com-pounds. Similarly, judges did not find odorant differences betweenbreads based on the same recipe but from different processes. Thiscould also be linked to their similar aromatic profile.

The different odorant perceptions perceived between commer-cial conventional, fully baked frozen and frozen dough breads onthe one hand, and commercial partially baked breads (frozen ornot) on the other hand, may be due to the lower quantity of Mail-lard compounds identified in the two latter. It may be that theywere characterised by fewer roasty, malty and sweet notes usuallygiven as descriptors for Maillard compounds (Pozo-Bayon et al.,2006). The lower content of these volatiles may be mainlyexplained by the different amounts of fresh yeast in commercialbreads (and not by the process). As previously shown (Zehentbauerand Grosch, 1998a,b), yeast content can influence the quantity ofMaillard volatile compounds in bread. Yeasts contribute to theformation of Maillard precursors, which are then transformed intovolatile compounds during bread baking (Schierberle, 1990;Zehentbauer and Grosch, 1998b). Thus, as the yeast content waslower in commercial partially baked breads, a smaller amount ofMaillard precursors were formed, leading to the release of a lowerquantity of Maillard volatile compounds compared to the otherthree commercial breads. Moreover, these differences did not seemto be linked to the baking time or temperature, as the bread coretemperature was constant at 100 �C for all the bread-makings.

The different amount of yeast in the five commercial breads alsoseemed to be responsible for the significant differences identifiedfor the compounds resulting from lipid oxidation. These resultsagree with those of Frasse et al. (1992), who demonstrated thata higher yeast activity induced a decrease in lipoxygenase activity.Indeed, this enzyme uses oxygen to convert fatty acids into alde-hydes, like hexanal, and alcohols, like 1-propanol, 1-pentanol, 1-hexanol, 1-octen-3-ol. Thus, the lower yeast content of commercialpartially baked breads may induce an increase in oxygen avail-ability, which could lead to an increase in the formation of volatilecompounds from lipid oxidation in these breads.

As commercial partially baked breads (frozen or not) containedless yeast in their recipe, smaller quantities of fermentative com-pounds were expected in their corresponding extracts (Frasse et al.,1992). However, this was not the case in our study. This could beexplained by the high quantity of ethanol found in their

corresponding extracts. It could also be the reason for the similartotal amount of volatile compounds found in all the commercialbread-makings. It could be linked to the high affinity of the SPMEfibre for this volatile compound. As significantly lower quantities ofMaillard compounds were released from commercial partiallybaked breads (frozen or not), ethanol that was trapped on the fibrewas slightly removed. Indeed, it did not enter into competition withMaillard compounds, leading to a significantly higher amount ofethanol extracted.

Moreover, the different amounts of fermentative compoundsextracted from conventional bread (R1C), frozen dough bread(R1FD) and partially baked bread (R1PB) based on the same recipe,could be explained by the significantly different quantities of ethylacetate, 2-methyl-1-propanol, 2-methyl-1-butanol and 3-methyl-1-butanol between these breads. However, while these compoundswere at lower levels in partially baked bread, its odorant perceptionwas similar to that of the other two breads studied. Thus, thequantitative difference identified for these volatile compounds didnot seem to have an impact on the perception of partially bakedbread.

This work revealed that the analysis of bread extract composi-tion linked to physical properties could be an interesting tool bothto characterise bread-making processes and to determine the in-fluence of the formula and the process on bread organolepticproperties. Nevertheless, it would also be interesting to study theeffect of a prolonged storage time on bread physical characteristicsand to link this with their aromatic profile.

The procedure followed in this work could then be applied toother matrices since the release of volatile compounds directlydepends on the nature of the foodstuff. This study could be theinitial step of a series that could target specific bread measure-ments, like the analysis of fermentative compounds released inrelation to crumb texture or the analysis of Maillard compoundsreleased according to the baking state.

Acknowledgements

This study was carried out with financial support from the Eu-ropean Commission, FP6, Thematic Area ‘‘Food Quality and Safety’’,FOOD-2006-36302 EU-FRESH BAKE. It does not necessarily reflectits views and in no way anticipates the Commission’s future policyin this area. The ENITIAA technical staff is gratefully acknowledged.We also thank the panellists for their participation in all the sensorysessions, and Vincent Varlet for his help.

P. Poinot et al. / Journal of Cereal Science 48 (2008) 686–697 697

References

Association Française de Normalisation (AFNOR), 2002. Recueil de normes frança-ises 2002: analyse sensorielle, sixth ed. AFNOR, Paris.

Aubry, V., Etievant, P.X., Ginies, C., Henry, R., 1997. Quantitative determination ofpotent flavor compounds in Burgundy Pinot Noir wines using a stable isotopedilution assay. Journal of Agricultural and Food Chemistry 45, 2120–2123.

Baardseth, P., Kvaal, K., Lea, P., Ellekjaer, M.R., Faergestad, E.M., 2000. The effects ofbread-making process and wheat quality on French baguettes. Journal of CerealScience 28, 73–87.

Baik, M.Y., Chinachoti, P., 2000. Moisture redistribution and phase transitionsduring bread staling. Cereal Chemistry 77, 484–488.

Barcenas, M.E., Haros, M., Benedito, C., Rosell, C.M., 2003. Effect of freezing andfrozen storage on the staling of part-baked bread. Food Research International36, 863–869.

Barcenas, M.E., Rosell, C.M., 2006. Effect of frozen storage time on the bread crumband aging of par-baked bread. Food Chemistry 95, 438–445.

Cauvain, S.P., 1998. Improving the control of staling in frozen bakery products.Trends in Food Science and Technology 9, 56–61.

Cayot, N., 2007. Sensory quality of traditional foods. Food Chemistry 101, 154–162.Daigle, P., Gelinas, P., Leblanc, D., Morin, A., 1999. Production of aroma compounds

by Geotrichum candidum on waste bread crumb. Food Microbiology 16,517–522.

Fik, M., Surowka, K., 2002. Effect of prebaking and frozen storage on the sensoryquality and instrumental texture of bread. Journal of the Science of Food andAgriculture 82, 1268–1275.

Frasse, P., Lambert, S., Levesque, C., Melcion, D., Richard-Molard, D., Chiron, H., 1992.The influence of fermentation on volatile compounds in French bread crumb.Lebensmittel-Wissenschaft und-Technologie 25, 66–70.

Galey, C., Potus, J., Drapron, R., Poiffait, A., Bar, C., Fischer, J., 1994. Les composesvolatiles de la mie du pain: etude de quelques facteurs de variation et conse-quences sur l’arome. Industrie des Cereales 89, 5–14.

Grosch, W., 1987. Reaction of hydroperoxides – products of low molecular weight.In: Chan, H.W.S. (Ed.), Autoxidation of Unsaturated Lipids. Academic Press,London, pp. 95–139.

Grosch, W., Schieberle, P., 1997. Flavor of cereal products – a review. CerealChemistry 74, 91–97.

Hansen, A., Schieberle, P., 2005. Generation of aroma compounds during sourdoughfermentation: applied and fundamental aspects. Trends in Food Science andTechnology 16, 85–94.

Javanainen, P., Linko, Y.Y., 1993. Mixed-culture pre-ferments of lactic and propionicacid bacteria for improved wheat bread shelf-life. Journal of Cereal Science 18,75–88.

Oruna-Concha, M.J., Bakker, J., Ames, J.M., 2002. Comparison of the volatilecomponents of eight cultivars of potato after microwave baking. Lebensmittel-Wissenschaft und-Technologie 35, 80–86.

Patel, B.K., Waniska, R.D., Seetharaman, K., 2005. Impact of different bakingprocesses on bread firmness and starch properties in breadcrumb. Journal ofCereal Science 42, 173–184.

Phimolsiripol, Y., Siripatrawan, U., Tulyathan, V., Cleland, D.J., 2008. Effects offreezing and temperature fluctuations during frozen storage on frozen doughand bread quality. Journal of Food Engineering 84, 48–56.

Poinot, P., Grua-Priol, J., Arvisenet, G., Rannou, C., Semenou, M., Le Bail, A., Prost, C.,2007. Optimisation of HS-SPME to study representativeness of partially bakedbread odorant extracts. Food Research International 40, 1170–1184.

Pozo-Bayon, M.A., Guichard, E., Cayot, N., 2006. Flavor control in baked cerealproducts. Food Reviews International 22, 335–379.

Ribotta, P.D., Leon, A.E., Anon, M.C., 2001. Effect of freezing and frozen storage ofdoughs on bread quality. Journal of Agricultural and Food Chemistry 49,913–918.

Ribotta, P.D., Le Bail, A., 2007. Thermo-physical assessment of bread during staling.Lebensmittel-Wissenschaft und-Technologie 40, 879–884.

Rouille, J., Le Bail, A., Courcoux, P., 2000. Influence of formulation and mixingconditions on breadmaking qualities of French frozen dough. Journal of FoodEngineering 43, 197–203.

Rychlik, M., Grosch, W., 1996. Identification and quantification of potent odorantsformed by toasting of wheat bread. Lebensmittel-Wissenschaft und-Tech-nologie 29, 515–525.

Schierberle, P., 1990. Studies on bakers yeast as source of Maillard-type breadflavour compounds. In: Finot, P.A., Aeschbacher, H.U., Hurrell, R.F., Liardon, R.(Eds.), The Maillard Reaction in Food Processing, Human Nutrition andPhysiology. Birkhauser, Berlin, pp. 187–196.

Vulicevic, I.R., Abdel-Aal, E.S.M., Mittal, G.S., Lu, X., 2004. Quality and storage life ofpar-baked frozen breads. Lebensmittel-Wissenschaft und-Technologie 37,205–213.

Zehentbauer, G., Grosch, W., 1998a. Crust aroma of baguettes. I. Key odorants ofbaguettes prepared in two different ways. Journal of Cereal Science 28, 81–92.

Zehentbauer, G., Grosch, W., 1998b. Crust aroma of baguettes. II. Dependence of theconcentrations of key odorants on yeast level and dough processing. Journal ofCereal Science 28, 93–96.