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Effect of the addition of different bres on wheat doughperformance and bread quality

Jinshui Wang a,b , Cristina M. Rosell a, *, Carmen Benedito de Barber aa Instituto de Agroqu mica y Tecnolog a de Alimentos (IATA), PO Box 73, 46100-Burjassot, Valencia, Spain

b Department of Food Engineering, Zhengzhou Institute of Technology, Zhengzhou 450052, Peoples Republic of China

Received 22 May 2001; received in revised form 21 January 2002; accepted 21 January 2002

AbstractA good correlation has become evident between bre consumption and the reduction of coronary heart-related diseases and

diabetes incidence. However, bre intake is commonly lower than recommended. In consequence, the development of foods withhigh bre content should be desirable. The potential use of various commercial bres (carob bre, inulin and pea bre), as bre-enriching agents in breadmaking, is reported. The effects of the addition of these bres to wheat our on the viscoelastic propertiesof dough and both mixing and proong behaviour is presented. Bread evaluation revealed that carob and pea bre supplementa-tion, although decreasing specic loaf volume (very slightly in the case of carob bre), conferred softness to the bread crumbs. Inaddition, sensory evaluation showed that consumer panellists judged these bre-enriched breads as acceptable. Therefore, their use,especially carob, allows an increase of the daily intake of bre without promoting negative effects on the rheological properties of doughs or quality and overall acceptability of the resulting breads. The whole study indicates that these three bres can be used asadditives in breadmaking in order to fortify the diet. # 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Dietary bre; Rheology; Dough properties; Breadmaking; Bread quality; Texture prole analysis

1. Introduction

Dietary bre (DF) is the food fraction that is not enzy-matically degraded within the human alimentary digestivetract. The main components are cellulose and lignin, butalso the hemicelluloses, pectins, gums and other carbohy-drates not digestible by human digestive tract (Stear,1990). The dietary bre is composed of total dietarybre (TDF), which includes both soluble (SDF) andinsoluble dietary bre (IDF). The importance of thedietary bre is increasing due to its benecial effects onthe reduction of cholesterol levels and the risk of coloncancer (Anderson, 1991; Whitehead, 1986). Healthauthorities, world-wide, recommend a decrease in theconsumption of animal fats and proteins and an increaseof cereal intake, which is an important source of dietarybre, and, in most European countries, cereals constitutethe major source of dietary bre. Nevertheless, whitebread is a commonly consumed type of bread. Therefore,

to meet this requirement for dietary bre, the develop-ment of enriched bread with a higher dietary bre con-tent should be the best way to increase the bre intake.

Bread can be enriched with dietary bre, includingwheat bran (Ranhotra, Gelroth, Astroth, & Posner,1990; Sidhu, Al-Hooti, & Al-Saqer, 1999), gums, suchas guar gum and modied cellulloses (Pomeranz, Sho-gre, Finney, & Bechtel, 1977), and b-glucans (Knuckles,Hudson, Chiu, & Sayre, 1997). However, the additionof these bres causes a neglected effect on the nalbread quality. The most evident effect is the reduction of loaf volume, the increase of crumb rmness, the darkcrumb appearance, and also in some cases a modiedbread taste is obtained, for instance, when adding guargum (Knuckles et al., 1997; Lai, Hoseney, & Davis,1989; Pomeranz et al., 1977). Moreover, the resultantbre-rich doughs have high water absorption, becomeshorter and have a reduced fermentation tolerance(Gan, Galliard, Ellis, Angold, & Vaughan, 1992; Lauri-kainen, Harkonen, Autio, & Poutanen, 1998; Park,Seib, & Chung, 1997).

Different proposals have been reported to solve theseproblems. One is the use of different milling fractions,

0308-8146/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.P I I : S0308-8146(02 )00135-8

Food Chemistry 79 (2002) 221226www.elsevier.com/locate/foodchem

* Corresponding author. Tel.: +34-96-390-0022; fax: +34-96-363-6301.

E-mail address: crosell@iata.csic.es (C.M. Rosell).

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since the particle size of the bran seems to play animportant role (Glitso & Bach Knudsen, 1999); how-ever, this has been a research approach without a pos-sible scale-up. Another alternative is the addition of exogenous enzymes, such as hemicellulases or pentosa-nases to degrade the cell walls (Haseborg & Himmel-

stein, 1988; Laurikainen et al., 1998). Nevertheless,there are currently emerging new bres from differentsources, which are potentially useful for making high-bre breads, whilst diminishing the inherent problemsassociated with the use of bres. Lately, Abdul-Hamidand Siew Luan (2000) have reported the potential use of defatted rice bran as a source of dietary bre in bread-making. They showed the effect of defatted rice branaddition on bakery products; this study was focussed onthe nal quality of breads showing a reduced loaf volume and increase rmness, although no informationwas presented relating to bread dough.

The aim of the present research was to determine thepotential use of various commercial bres from differentsources, through a systematic study of the inuence of several bres on the rheological properties of breaddoughs and the nal quality of the resulting breads. Thesensory evaluation and nutritional value of these enrichedbreads were also evaluated.

2. Materials and methods

2.1. Materials

A commercial blend of wheat our (14.6% moisture,11.3% protein and 0.61% ash) was used. Three differentbres (carob bre, chicory inulin and pea bre) wereused to make enriched bre bread. Carob bre (CF) wasdonated by Carob General Applications, S.A. (Spain),whereas chicory inulin and pea bre were gifts from Julia -Parrera, S.A. (Spain). Commercial compressed yeastwas used for the breadmaking.

2.2. Methods

2.2.1. Chemical analysisMoisture, ash, and protein were determined following

standard AACC methods (1983). Nitrogen content wasmeasured by the semimicro-Kjeldahl method. Nitrogenwas converted to protein by using a factor of 5.7. Soluble,insoluble and total dietary bre content was determinedaccording to the AACC Method (1996).

2.2.2. Dough characteristicsThe effect of the different bres on dough rheology

during mixing was determined by a Farinograph (Bra-bender, Duisburg, Germany), following the AACCMethod (1983). The parameters determined were: waterabsorption or percentage of water required to yield

dough consistency of 500 BU (Brabender Units), doughdevelopment time (DDT, time to reach maximum con-sistency in minutes), stability (time dough consistencyremains at 500 BU), mixing tolerance index (MTI, con-sistency difference between height at peak and that 5min later, BU) and elasticity (band width of the curve at

the maximum consistency).The viscoelastic behaviour of the dough was determinedby the alveograph test, using an Alveograph MA82(Tripette et Renaud, France), following the standardmethod (AACC, 1994). The monitored parameters werethe deformation energy ( W ), tenacity or resistance toextension ( P ), dough extensibility ( L ) and curve cong-uration ratio ( P /L ratio) of dough, with or withoutbres. The proteolytic degradation was determined bymeasurement of the alveograph parameters after 3 h of dough pieces incubation (Colas, 1974).

The rheological properties of dough during fermenta-tion were determined using a Rheofermentometer F2(Tripette et Renaud, France), according to the supplierspecications. Registered parameters: maximum doughfermentation height ( H m ), the time at which doughattains the maximum height ( T 1), loss in dough heightafter 3 h (Vol.loss), the time of maximum gas formation(T 01), dough permeability by time when gas starts toescape from the dough ( T x), and the gas retention (volumeof the gas retained in the dough at the end of the assay).More information about this equipment is reported byErdogdu-Arnoczky, Czuchajowska, and Pomeranz(1996), and Rosell, Rojas, and Benedito (2001).

Alveogram and rheofermentogram studies were car-

ried out at the same dough consistency as control(without bre), since water adsorption was greatlymodied by the addition of bres.

All determinations were made at least in duplicate,and the average values were adopted.

2.2.3. Baking testsA straight dough breadmaking process was per-

formed. Basic dough formula on 100 g our basis con-sisted of salt (2 g), compressed yeast (2 g), ascorbic acid(50 ppm), the amount of water required to reach 500BU of consistency, and 3% bre (when added). Carobbre, inulin and pea bre were used as commercialbres with potential use for enriching breads. Thedoughs were optimally mixed, fermented for 10 min,then dough pieces (100 g) were divided, hand-mouldedand sheeted. Doughs were proofed at 28 C up to opti-mum volume increase, and baked at 190 C for 20 min.The bread quality attributes were evaluated after coolingfor 1 h at room temperature.

2.2.4. Bread quality evaluationBread quality parameters included weight, volume

(determined by seed displacement in a loaf volumemeter), specic volume, moisture content, acceptance

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and texture of crumb. Overall acceptability was carriedout as follows: one slice of bread, identied by codenumbers, was served to each panellist under normal(daylight) illumination. They evaluated each product forquality attributes: grain, crumb smoothness, aroma,avour and overall acceptability. Acceptability of each

quality attribute was rated with a score 1 (lowest) to 10(highest). Products were considered acceptable if theirmean scores for overall acceptability were above 5 (neitherlike nor dislike).

Texture prole analysis (TPA) was performed using aTA-XT2i texturometer (Stable Microsystems, Surrey,UK) equipped with a 2.5 cm plug. Crumb slices of 2 cmwere 50% compressed. Four replicates from two differentsets of baking were analysed and averaged. The para-meters recorded were hardness, chewiness, cohesiveness,springiness and resilience.

3. Results and discussions

3.1. Inuence of bres on dough properties

Before determining the effect of the different bres ondough rheology, their composition was assessed(Table 1). The contents of TDF, SDF and IDF in thethree bres used in the research are listed in Table 1.The main difference among them was the compositionof the insoluble dietary bre. The carob bre IDF iscomposed mainly of lignin and polyphenol; the inulin isa mixture of oligo- and polysaccharides of fructose and

the pea bre IDF contains a majority proportion of cellulose.

3.1.1. Inuence of bres on mixing propertiesThe addition of bres promoted differences on the

dough mixing behaviour measured by the farinograph.

Table 2 shows the main parameters registered in thefarinogram. Fibre addition mainly modied the waterabsorption. Apart from inulin, a great increase wasproduced by the addition of bres and the extent of theincrease depended upon the structure of the bresadded. The highest absorption was found with theaddition of pea bre, followed by carob bre. Similareffects on water absorption were observed when addingwheat bran (Pomeranz et al., 1977), rye bran (Laur-ikainen et al., 1998), and rice bran (Barber, Benedito deBarber, & Martinez, 1981). This is likely caused by thegreat number of hydroxyl groups existing in the brestructure, which allow more water interactions throughhydrogen bonding, as was previously found by Rosell etal. (2001), working with different hydrocolloids. Doughdevelopment time (DDT) and stability value are indica-tors of the our strength, with higher values suggestingstronger doughs. These bres did not modify the DDTor the stability (with the exception of inulin whichincreased it), in opposition to the results reported byLaurikainen et al. (1998), who found an increase of theDDT and a decrease of the stability when adding 5%rye bran. Greater effects were observed on the MTI andelasticity; both parameters were reduced by the additionof the tested bres, and the extent of the decrease

depended on the bre considered. These results could beexplained by the interactions between bres and gluten,as suggested Chen, Rubenthaler, and Schanus (1988).The farinogram result shows that the addition of inulinconfers different mixing properties to the dough, surelydue to its composition in polysaccharides of fructose.

3.1.2. Inuence of bres on the viscoelasticcharacteristics of wheat dough

The effects of added bres on the alveograph char-acteristics of wheat our doughs are seen in Table 3. The Pvalue (dough resistance to deformation or tenacity) is anindicator of the doughs ability to retain gas. P valuesincreased with the addition of the three different bres.The highest effect was exhibited by inulin, followed byCF, and the lowest inuence was by PF. This is likely

Table 1Composition of the commercial bres used in this study

Components (%) a Carob bre Inulin Pea bre

Dry matter b 97.0 96.3 94.4Protein 6.4 7.1 5.5Ash 2.2 1.7 1.4Fat < 0.5 < 0.5 < 0.5

Carbohydrates c

Total dietary bre 85.0 88.6 86.7Insoluble dietary bre 74.0 41.4 79.8Soluble dietary bre 11.0 47.2 6.9

a Dry basis.b As-is basis.c Calculated by difference.

Table 2Farinograph analysis of wheat dough containing different bres (for abbreviations, see Section 2)

Water adsorption (%) DDT (min) Stability (min) MTI (BU) Elasticity (BU)

Control 53.5 2.0 4.0 90 110Carob bre 57.3 2.0 4.0 70 100Inulin 52.0 2.0 5.0 50 90Pea bre 59.9 2.0 4.0 75 90

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due to interactions between the bre structure and thewheat proteins, as previously reported Jones andErlander (1967), who reported interactions betweenpolysaccharides and proteins from wheat our.

Additionally, L (the extensibility of dough), a pre-dictor of the processing characteristics of the dough,was greatly reduced by adding bres, with the exceptionof inulin, which did not modify L . The highest effectwas promoted by pea bre, yielding a reduction of about 42% in the extensibility of the wheat our, andhence a smaller bubble before failure. The resultingeffect on P and L became evident in the P /L ratio value,which provides information about the elastic resistanceand extensibility balance of our dough.

The addition of pea bre led to the highest P /L ratio (0.9vs 0.5 in the control), probably due to the high content of

cellulose present in this bre, which favours a stronginteraction between this bre and the our proteins.The inuence on W (the deformation energy) depen-

ded on the bre considered. W was reduced by pea breaddition, while it was increased by CF and inulin,reaching, in the latter, the highest value (161 vs 119 inthe wheat our). It is important to note that the addi-tion of bres promoted a marked decrease of the pro-teolytic degradation, being practically neutralised byinulin and carob bre, and therefore the addition of these two bres led to a great improvement of wheatprotein behaviour, allowing long proong times.

3.1.3. Fermentation behaviour of doughs with bresThe evolution of dough properties throughout the

fermentation can be continuously registered by therheofermentometer, which gives information aboutdough development, gas production and gas retention(Bloksma, 1990). The inuence of bre additions on thefermentation characteristics is shown in Table 4. Doughheights, when supplemented with bres, decreasedcompared to the wheat dough. These were in agreementwith the decline of the extensibility and the resistanceincrease measured by the alveograph. Probably, theinteractions between our proteins (gluten) and these

bres prevent the free expansion of wheat dough duringthe proong stage.

The time to reach the maximum dough development(T 1) was not affected by CF, whereas it was reduced bythe addition of inulin and pea bre; this result indicatesthat fermentations of doughs containing these bres needless time to reach the maximum than does the control. Inaddition, inulin and CF decreased the percentage of volume loss, which means higher dough stability than thecontrol. Therefore inulin and CF improve dough charac-teristics, allowing longer proong times.

With respect to gas behaviour, T 01 (the time of max-imum gas formation) and T x (the time at which gasstarts to escape from dough) were decreased by breaddition, which revealed an increase of the dough per-meability to carbon dioxide. Galliard (1986) and Gan,

Ellis, Vaughan, and Galliard (1989) found that theaddition of particulate components, especially bran andepicarp bres, to doughs promoted a physical disrup-tion of the gluten protein matrix. They explained this byassuming that bres act as points of weakness or stressconcentrations within the expanding dough cell walls.

However, no change in the relationship between gasproduction and retention, that is the percentage of gasretention (%), was found. Conversely, Pomeranz et al.(1977) assumed that the loaf volume-depressing effect,caused by the addition of cellulose, bran or oat hulls,could be due to a decreased capacity for gas retention.

3.2. Inuence of bres on bread quality evaluation

The effect of the bre supplementation on breadquality characteristics is summarized in Table 5. Fibre-rich breads, with CF, inulin or PF, had smaller loaf volumes than the control. The addition of pea brepromoted the greatest volume reduction (20.7%). Interms of specic bread volume, inulin and PF promotedthe greatest decrease. The reductions obtained werecomparable to those previously reported with addedbran, cellulose, or other polysaccharide (Knuckles et al.,1997; Laurikainen et al., 1998; Pomeranz et al., 1977).

Table 4Inuence of bre supplementation on the wheat dough behaviourthrough fermentation (abbreviations are specied in Section 2)

Control a Carob Fibre Inulin Pea Fibre

Dough developmentH m (mm) 33.5 31.9 30.2 29.4

T1 (min) 70 69 60 58Vol. loss (%) 25.3 21.3 0.0 57.9

Gas behaviourTx (min) 73 67 49 61T 0 1 (min) 87 57 63 51Gas retention (%) 81.8 81.7 81.3 81.4

a Control is referred to dough without bre.

Table 3Effect of the bre addition on the alveoghaph characteristics of awheat our a

Control b Carob bre Inulin Pea bre

P (mm H 2O) 48 57 60 53L (mm) 107 81 106 62

W ( 104

J) 119 128 161 102P /L ratio 0.5 0.7 0.6 0.9Proteolytic degradation (%) 18.5 2.3 0 9.8

a P , the resistance to deformation; L , dough extensibility; W , theenergy input necessary for deformation; P /L , the conguration curveratio.

b Control is referred to dough without bre.

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Rogers and Hoseney (1982) reported that whole wheatour dough, which contains mostly insoluble bre, hada normal proof height and a normal spread ratio butgave only a slight oven-spring; they attributed this resultto an early xing of the structure and a high level of water in the dough. In fact, bre-rich breads havehigher moisture contents than the control, as can beobserved in Table 5. Bread containing inulin was the

exception to this trend, since the moisture content waslower than the control.The texture prole analysis revealed that inulin addi-

tion increased crumb rmness, contrasting with thesofter crumbs obtained with the addition of carob andpea bres. The same trend was observed with the che-winess, and the other parameters from the TPA did notshow important changes. The crumb softness effectproduced by the CF and PF supplementation is note-worthy, since the addition of bres usually leads to rmcrumbs.

Breads containing bres were judged by the consumerpanellists as acceptable, scoring > 5 for each specicsensory characteristic and overall acceptability (Table 5).Moreover, the sensory evaluation of the bre-enrichedbreads tested in this study was far superior to thoseobtained with other bres cited in the literature (Abdul-Hamid & Siew Luan, 2000; Knuckles et al., 1997).

3.3. Dietary bre composition of the bre-enriched breads

As can be seen in Table 6, the TDF of the bre-enri-ched breads was higher than the content of the control(no added bre). The increase ranged from 71% with

added CF to 82% with PF, compared to the control.However, the TDF content was less than expected,considering the amounts added. These results are inagreement with those previously found by Abdul-Hamid and Siew Luan (2000), after adding defatted ricebran and sugar beet bre. They suggest that some diet-ary bre could be hydrolysed by yeast enzymes or lostduring baking (mainly the soluble dietary bre). Thelatter explanation seems to be the right one, since theIDF content coincided with that predicted, according tothe amount added, and the SDF was much less thanexpected. Inulin addition augmented TDF content of this bre-enriched bread, but the increase was due to asimultaneous rise in IDF and SDF, especially in SDF.

4. Conclusion

From the overall results, it could be concluded thatthe addition of bres (carob bre, inulin and pea bre)to wheat our modies the rheological properties of the

dough to a in less extent than bran. The addition of those bres increased the conguration curve ratio ( P /L ) and improved proong stability was obtained withcarob bre and inulin. In addition, the bread qualitycharacteristics were acceptable; conversely, breads en-riched with CF and PF showed softer crumbs than thecontrol.

The bre-rich breads obtained were also consideredacceptable by the sensory panel. The dietary bre com-position of the nal products revealed that these bresare good for use as bre-enriching agents in breadmak-ing. Carob bre was the product with the most promis-ing potential in the development of bre-rich bread inorder to increase the daily bre intake.

Acknowledgements

This study was nancially supported by the EuropeanUnion and Comisio n Interministerial de Ciencia y Tec-nolog a Project (FEDER, 1FD970671-C0201) andConsejo Superior de Investigaciones Cient cas (CSIC,Spain). Jinshui Wang would like to acknowledge the grantfrom the China Scholarship Council (CSC) and AgenciaEspan ola de Cooperacio n Internacional (AECI).

Table 5Effect of dietary bre supplementation on the wheat bread evaluation a

Control b Carob bre Inulin Pea bre

Loaf volume (ml) 906 861 733 719Specic volume (ml/g) 3.5 3.4 2.9 2.8Moisture content (%) 33.4 35.3 31.8 35.7

TPA parametersHardness 249.3 205.7 268.4 207.3Chewiness 192.4 157.8 198.4 158.3Cohesiveness 0.797 0.799 0.792 0.797Springiness 0.969 0.973 0.962 0.972Resilience 0.472 0.447 0.439 0.444

Sensory analysis c

Grain 6.2 6.3 5.2 5.9Crumb smoothness 6.0 6.2 5.4 6.7Aroma 6.9 6.1 6.7 7.2Flavour 7.1 5.7 6.7 6.4Overall acceptability 6.8 6.1 6.3 6.1

a Texture prole analysis (TPA) and sensory analysis is included.

For experimental details see Section 2.b Control is referred to dough without added bre.c Nine point hedonic scale ratings: 9=like extremely and 1=dislike

extremely.

Table 6Effect of bre addition on the dietary bre composition of bre-enri-ched breads

Control a Carob bre Inulin Pea bre

Total dietary bre (%) 2.96 5.06 5.14 5.38Insoluble dietary bre (%) 2.42 4.67 3.14 4.94

Soluble dietary bre (%) 0.54 0.39 2.00 0.44a Control is referred to bread without added bre.

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