Pertanika 1(1), 7-16 (1978)

Use of Cassava and Winged Bean Flour in Bread-Making

NG ENG GIM1 and KHOR GEOK LINDepartment of Home Technology, Universiti Pertanian Malaysia

Key words: Cassava, Winged Bean, Bread-making

RINGKASAN

Satu kajian telah dijalankan untuk menilai kemungkinan menggantikan separuh daripada tepunggandum dengan tepung ubikayu dalant membuat roti, dan memperkayakan rotiyang dibuat dari tepunggandutn-ubikayu dengan tepung kacang botoL Adunan yang disediakan dengan sukatan tepung ubikayu yang lebihtinggi didapati mengurangkan penyerapan air, masa pembentukan adunan dan kestabilan adunan, menyebabkanadunan menjadi lembut. Sukatan penggantian yang lebih tinggi dengan tepung ubikayu juga menambahkan€ ekstensibilitV adunan, dan kurang rentan untuk kegiatan amilasa dan menghasilkan adunan yang lebih kental.Dengan campuran tepung kacang botol, ciri-ciri adunan ini berubah sedikit. Hingga 30% penggantian dengantepung ubikayu (70-30) dan dengan 5% perkayaan dengan tepung kacang botol (75-20-5), telah memberikanisipadu buku roti, isipadu khusus buku roti dan mutu-mutu organoleptik yang memuaskan. Kajian ini jugamendapati bahawa jangka masa simpanan untuk roti yang mengandungi 9% tepung kacang botol (70-21-9)ialah 4 hari sebelum ia menjadi apak pada suhu bilik (27°C) dan dalam peti sejuk (9°C), berbanding dengan4 dan 6 hari, masing-masing, untuk rotiyang dibuat dengan 100% tepung gandum, Pada umumnya, kandungan(75-20-5) dijangkakan boleh memberi keputusan yang memuaskan.

SUMMARY

The feasibility of partially replacing wheat flour by cassava flour in bread-making, and the fortificationof the wheat-cassava composite bread with winged bean flour was studied and evaluated. Dough prepared withan increased level of cassava flour was found to reduce water absorption, development time and stability of thedough. Higher levels of substitution with cassava flour increased dough extensibility, and reduced susceptibilityto amylase activity, resulting in a more viscous dough. The incorporation of winged bean flour improved thesedough characteristics. Up to 30% substitution with cassava flour (70 - 30) and 5% fortification with wingedbean flour (75-20-5) yielded acceptable loaf volume, specific loaf volume and organoleptic characteristics.It was determined that the shelf life of the bread made with 9% winged bean flour (70-21-9) was 4 daysbefore staling at room temperature (27°C) and in the refrigerator (9°C), compared to the 4 and 6 day periodstaken for the 100% wheat bread to stale under similar conditions. In general, the (75 -20-5) compositionwas deemed to produce the most promising results.

INTRODUCTION

The use of indigenous raw materials asdiluents of wheat in the production of compositeflour for bread-making first gained impetus in1964 when the Food and Agriculture Organi-sation was requested to look into the use ofcassava (Manihot esculenta) flour for makingbread. The request came from New Guinea,where import of Australian wheat was difficultand expensive, and where the use of cassavawould aid local development. Since then thesocio-economic significance of the compositeflour program has been widely recognised andresearch has been pioneered in institutions such

as the Tropical Products Institute, England;Institute for Cereals, Flour and Bread, TNO,Netherlands and Kansas State University, UnitedStates.

Research and field programmes on the useof composite flour does not only include theutilisation of local carbohydrate-rich resourcessuch as cassava, yam, sago, rice, corn, sorghum,millet, barley, sweet potato and potato, but suchstudies also include the use of protein supple-mentation with flours prepared from soya bean,cotton-seed, peanut, safflower, defatted fish, driedskim milk, whey and yeast extract (Kasasian andDensy, 1977). Bread is a convenient food item for

Institut Pertanian, Bumbong Lima, Province Wellesley.

NG ENG GIM AND KHOR GEOK LIN

protein fortification for young children sufferingfrom protein malnutrition particularly in theless industrialised countries.

One main drawback faced by these countriesin bread production lies in their dependence onwheat imports. In 1976 Peninsular Malaysiaimported more than 399,000 tons of unmilledwheat valued at $156.8 million (Mins. Agric.and Rural Development 1977). A substantialportion of the imported wheat goes toward theproduction of bread and confectionery such ascakes and biscuits. Hence, one of the ways ofreducing wheat imports is through the use ofnon-wheat flours in bread, cakes and biscuits.

This study was undertaken to evaluate theextent to which wheat flour can be replaced bycassava flour in the making of bread; and to studythe rheological feasibility of incorporating flourfrom a locally grown legume, winged bean(Psophocarpus tetragonolobus (L) DC), as a proteinsupplement of the cassava-wheat bread.

MATERIALS AND METHODS

The wheat flour (Twinspoon brand) usedwas manufactured by the Federal Flour Mills(M) Bhd., Port Klang. Cassava flour packed byKian Hin (M) Sdn. Bhd., Kuala Lumpur, wasused. Flour from the winged bean was obtainedby grinding dried and dehulled bean seeds in aJunior Laboratory Mill (Christy and Norris,England) and passing the powder through a meshof 0.7 mm diameter. Other ingredients includedgranulated sugar from Malayan Sugar Manu-facturing Co., Bhd., Prai, and compressed yeast("Pinnacle" brand) produced by Mauri Fermen-tation (Malaysia) Sdn Bhd., Sungei Besi.

Chemical analyses of the flour and bread

Proximate analyses of the various samples offlour and bread were carried out according tothe official methods of the Association of OfficialAgricultural Chemists (A.O.A.C, 1975). Thegluten content of the wheat flour was determinedby the Hand Washing Method as described inthe Approved Methods of the American Asso-ciation of Cereal Chemists (A.A.C.C, 1969).

Rheological evaluation of the dough

Rheological characteristics of the doughswere evaluated using the Brabender Farinograph,Extensograph and Amylograph (BrabenderInstruments, Inc., Germany).

Baking recipe and procedure

The composition of the ingredients for thecontrol bread (100% wheat flour) is the standardrecipe:

Wheat flourCompressed yeastSaltSugarMargarineMilk powderWater

605 g10 g

7.1 g13.0 g12.1 g6.1 g380 ml (approximately)

(Duplicate loaves were sealed at 454 g. each)

Loaves containing different percentages (byweight) of the cassava starch and winged beanflour were prepared by substituting the wheatflour in the standard recipe. Duplicate loaveswere baked for each level of substitution. Controlloaves were prepared for each baking trial.

Baking was carried out in the Cereal Labora-tory at the Agricultural Products Utilization(A.P.U.) division of the Malaysian Agri-culture Research and Development Institute(M.A.R.D.I.). All the ingredients were mixedat room temperature in the Herbst Dough Mixerwith optimum water absorption and mixing time.The dough was then fermented at 27°C in aproofing cabinet. The first proofing was for1 h 20 minutes. Intermediate proofing after'knock-back' was for 40 minutes. The doughwas then scaled to 454 g. The final proofingtook 1 hour. In the final proofing the tempera-ture of the proofing cabinet was raised to about38°C. The loaves were then baked at 218°Cfor 30 min. in the Simon Rotary Test Oven.

Evaluation of bread characteristics

Bread characteristics or baking qualitieswere evaluated by measuring the loaf volume,the specific loaf volume and the organolepticcharacteristics. Loaf volume was measured(30 min. after the loaves were removed from theoven) by displacement of sago 'pearls' of diameterabout 2 mm. The specific loaf volume wasobtained by dividing the loaf volume by itscorresponding loaf weight.

Sensory evaluation was performed about20 h after baking to evaluate the crust color,crust toughness, crumb color, crumb texture,flavour and crust/crumb ratio. The bread sam-ples were sliced into pieces of uniform thicknessand size and served plain with water. Eightpanel members were randomly selected fromstaff members and students for the evaluation.

CASSAVA AND WINGED BEAN IN BREAD-MAKING

Comparison of shelf life of breadBoth control and experimental bread were

wrapped in polyethylene bags of 0.045 mmthickness after sufficient cooling and kept atroom temperature (26.5 to 28°C) and in therefrigerator (9°C) to simulate the usual mannerof storing bread in the home. The bread wastested for freshness at 2 day intervals over an8 days' storage period. Bread freshness/stalenesswas tested according to the Sensory ReceptionTest as described by the A.A.C.C. (1969).

Statistical analysesAnalyses for significant differences in the

results obtained were performed by using theF-test. (Spence, et aL, 1968) and the LeastSignificant Difference test (Le Clerg, et al.} 1962).

RESULTS AND DISCUSSION

Chemical Composition of the floursResults from the proximate analyses and

gluten determination of the 3 different types offlour used are as shown in Table 1.

The wheat flour was found to have a crudeprotein and gluten content of 14.18% and 13.19%respectively. According to Zeleny (1971) aminimum protein content of 11% in wheat flouris necessary for the production of yeast-leavenedbread. The importance of the protein level isdue to its gluten fraction in that gluten is respon-sible for the elasticity of the dough by causing itto extend and trap the carbon dioxide generatedby yeast during fermentation. When glutencoagulates under the influence of heat duringbaking, it serves as the framework of the loafwhich becomes relatively rigid and does notcollapse.

Neither cassava flour nor winged bean flourcontain any gluten. Consequently, neither can

be utilised solely for making bread; and whenused, a limit is necessarily imposed on the extentto which either flour can be used as a substitutefor wheat flour in bread-making. Nevertheless,the high protein content of winged bean flour(46.49%) can serve as a useful protein supplementof bread made partially from cassava flour, asthe latter, with a negligible protein content of0.19%, would tend to decrease the overall proteinlevel in the wheat-cassava composite flour. More-over the blending of a legume protein with thatof cereal improves the protein quality because therelatively high lysine content in winged beancomplements the rather low lysine level in wheatflour. (Milner, 1973).

Farinograph resultThe dough behaviour of the various flour

mixtures is shown in Table 2. Increasing thecassava flour in the dough reduced water absorp-tion, dough development time and dough stabilityresulting in increased dough softening or weaken-ing. When winged bean flour was added up to9% of the mixture these mixing properties wereimproved, although the dough softening remainedat 95 Farinograph units equaled that recordedfor the 70-30% mixture. Reduction in doughdevelopment time and dough stability were foundalso with soya-wheat flour (Tsen and Hoover,1973).

Extensograph resultThe stretchability of a dough is characterised

by the parameters given in Table 3. Theenergy of the dough, i.e. the total force used instretching the dough decreased with an increasein the level of substitution with cassava flour.This is further reflected by the decreasing trendin the resistance of the dough to extension.Hence the extensibility, which indicates thestretchability of the dough, was reduced accord-ingly.

TABLE 1

Chemical Composition of the Flours

(dry matter basis)

Flours

Wheat flour

Cassava flour

Winged bean flour

a = %N x 5.7

b - %N x 6.25

Gluten

13.19

0.00

0.00

Crude protein

14.18a

0.19b

46.49b

Crude fiber(%)

trace

2.49

5.63

Ether extract

1.04

0.88

26.22

Ash

0.36

0.07

2.99

1000293691

TABLE 2Farinograph characteristics of the doughs with different levels of substitution of wheat

by cassava flour and winged bean flourflour

Dough samples

WaterAbsorption

(0/ \

\ /o)

Doughdevelopment

time(0/ \

( /o)

Doughstability

(min)

Doughsoftening

(Farinographunits)

100% wheat flour (control)

90-10% (wheat-cassava)

70-30%

50-50%

75-2O-5a

70-21-9b

67.9

64.2

60.3

58.7

65.9

68.4

8.3

6.5

2.5

1.0

7.5

8.0

14.5

13.5

7.5

2.0

10.5

11.5

45

55

95

165

87.5

95

a : 75% wheat, 20% cassava flour and 5% winged bean flour.b : 70% wheat flour, 21 % cassava flour and 9% winged bean flour.Values obtained were averages of 3 replicates.

TABLE 3Extensograms of the doughs with different levels substitution of wheat flours by cassava flour and winged bean flour

Dough samples

100% wheat flour (control)

90-10% (wheat-cassava)

70-30%

50-50%

75-20-5 %a

70-21-9%b

Energyof dough

(cm2)

187

155

106

29.5

93

92

Resistanceto extension

(Extensographunits)

870

860

850

350

790

770

Extensibility(mm)

150.5

132.5

100

64.5

107.5

100

Ratio ofresistance/

extensibility

5-78

6.49

8.50

5.43

7.35

7.70

a : 75% wheat, 20% cassava, 5% winged bean.b : 70% wheat, 21% cassava, 9% winged bean.

It was noted that the value for the resistanceto extension decreased gradually from 870 Exten-sograph units for the 100% (control) to 850 unitsfor the 70-30% mixture. This could be attri-buted to the high resistance of the wheat flourwhich adequately compensated for the lack ofresistance to stretching of the cassava flour. Inthe 50-50% mixture the weak stretching behaviourof the dough decreased to only 350 units. Theaddition of winged bean flour gave readingscloser to those for the 70-30% mixture.

Amylograph result

It is common knowledge that the gelatini-zation of starch within the loaf during bakinginfluences the condition of the crumb. TheAmylograph simulates the effect of baking onstarch by raising the temperature of a flour/watersuspension at a constant rate, during which thestarch gelatinizes.

A lowering in the pasting temperature withincreased use of cassava flour indicates that thisstarch gels at a lower temperature than wheatstarch (Table 4).

The peak viscosity temperature of the starchdecreased at the 50-50% mixture possibly becauseof the fast rate of gelatinization of the cassavastarch at high concentrations.

The viscosity of the starch during gelatini-zation is an inverse function of the amylaseactivity. The increase in viscosity with increasedcassava flour concentration indicates a reductionin the amylase activity. This leads to lowercarbon dioxide production during fermentationresulting in poor loaf volume. Winged beanflour helped to increase the amylase activity asshown by the decreased peak viscosity.

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TABLE 4

Viscosity of the doughs with different levels of cassava flour and winged bean flourduring the gelatinization of the starch

(60 g dry solids/450 ml water)

Flour samples Pasting temperature Peak viscosity(Brabender Units)

100% wheat flour (control)

90-10% (wheat-cassava)

70-30%

50-50%

75-20-5 %a

70-21-9%b

73

66

66.5

68

67

68

a : 75% wheat, 20% cassava, 5% winged bean,b : 70% wheat, 21% cassava, 9% winged bean.

Loaf volumeFig. 1 shows that as the level of cassava flour

was increased beyond 30%, loaf volume decreasedsignificantly. With the addition of winged beanflour, it was found that the 70-21-9 mixture alsoyielded a significantly poorer loaf volume, butthe 75-20-5 mixture gave a loaf volume notsignificantly different from that of the control.The loaf volume of the various mixtures can beseen from the heights of the bread slices in Plates

890 (at 93°C)

910 (at 92°C)

998 (at 91 °C)

905 (at 75°C)

840 (at 91 °C)

695 (at 91 °C)

1-6. Other researchers have found a similarreduction in volume when non-wheat flours wereused. (Dendy and Clarke, 1969; Hasmeyer,et al 1976).

Specific loaf volumeThe specific loaf volume which indicates the

compactness of the loaf was determined for eachlevel of substitution and fortification as shownin Fig. 2. The specific loaf volume decreased

Fig. 1:% Cassava flour % Cassava flour

Loaf volume at different levels of substitu-tion of the wheat flour

loaf volume of 75 - 20 - 5 bread aloaf volume of 70 - 21 - 9 bread Aline below which the loaf volumes are significantlydifferent from that of the control at 5% confidencelevel.

Fig. 2: Specific loaf volume at different levels ofsubstitution of wheat flour

specific loaf volume of 75-20-5 bread Dspecific loaf volume of 70-21-9 bread Alines below which the specific loaf volumes aresignificantly different from that of the control at5% confidence level.

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Plate 1

Control Bread (100% wheat flour).

Plate 2

90% wheat: 10% cassava

Plate 3

wheat: 30% cassava

12

Plate 4

50% wheat: 50% cassava

CASSAVA AND WINGED BEAN IN BREAD-MAKING

Plate 575% wheat: 20% cassava: 5% winged bean

Plate 670% wheat: 21% cassava: 9% winged bean

as the level of cassava flour increased. Beyondthe 30% level the specific loaf volume was signi-ficantly less than that of the control bread. Thistrend was also observed by Lawhon, et al. (1974)using glandless cotton seed flour in the blend.There was a slight increase in the specific loafvolume with 5% winged bean flour and a markeddecrease in volume when it was increased to 9%.

Organoleptic characteristicsAcceptability of the bread prepared from

the various mixtures was evaluated and the scoresobtained are shown in Table 5. For mixturesup to 30% of cassava flour, the scores for crustcolour, crust toughness, crumb colour, crumbtexture, flavour and crust/crumb ratio were notsignificantly poorer than those for the controlbread. In fact better scores for crumb textureand crust/crumb ratio at 10% cassava flour wereobtained. The overall score for bread with10% cassava flour was therefore higher than thatfor the control.

The overall score for 30% cassava flour(21.43) was within the bounds of acceptability,but 40% cassava flour had significantly lowerscores for all the characteristics evaluated. Exceptfor its crust/crumb ratio which was judged accept-able and not significantly different from that ofthe control, 50% cassava flour was also scoredpoorly on other counts. Poor scores in crustcolour could be attributed to the paler colourobtained with increased concentration of cassavaflour, which was also responsible for the un-acceptable yellowish crumb. Poor crumb accept-ability could be due also to the coarser texturecaused by adding cassava flour.

The 75-20-5 bread was found to have muchhigher bread scores than the 70-21-9 bread inall respects. The crust colour of the 70-21-9bread was significantly poorer than that of thecontrol due to its paler colour. The crumbcolour and flavour were actually slightly belowthe acceptable level. Crumb colour becamepoorer with increased concentration of the wingedbean flour due to the slight brownish and greyishcolour of the bean flour.

Flavour was found to be a prominent factorin determining acceptability of the bread fortifiedwith winged bean flour. At 5%, the flavour wasacceptable but when the flour was increased to9%, there was a drop in the flavour score toslightly below the acceptable level. Higherlevels of fortification with winged bean flourwould be undesirable because it would grosslyaffect flavour.

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TABLE 5

The scores for the organoleptic characteristics of the bread with different levels ofthe cassava flour and winged bean flour

Bread samples

100% wheat flour(control)

90-10% (wheat-cassava)

80-20%

70-30%

60-40%

50-50%

75-20-5% wheat-

70-21-9% wingedbean

Crustcolour

4.25

4.43

3.14

4.00

2.00*

2.14*

4.57

2.57*

Crusttoughness

4.08

4.14

3.57

3.57

2.29*

2.43*

3.86

3.13

Crumbcolour

4.18

4.71

4.14

4.14

2.71*

2.71*

4.14

2.86

Crumbtexture

4.27

4.86*

3.71

3.71

1.86*

1.86*

4.57

3.57

Flavour

4.18

4.71

3.29

3.57

1.86*

2.43*

3,43

2.86

Crust/crumbratio

4.18

5.00*

3.86

3.00

2.42*

3.00

5.00

3.29

Overallscore

(out of 30)

25.14

28.00

21.71

21.43

13.00*

14.57*

25.57

17.71

Scores 5 = good3 — acceptable1 = poor

* P <0.05

Shelf lifeEvaluation of shelf-life was done by com-

paring the freshness of the 70-21-9 bread withthat of the control bread. The scores for breadfreshness are presented in Table 6. At roomtemperature of about 27°C, both types of breadwere found to be slightly stale by the fourth dayof storage.

Cheng et al (1976) found the shelf life ofbread prepared with 20.2% cassava flour andfortified with 9% soya flour to be 2 - 3 days at27°C. In this study, when kept in the refrigerator(at 9°C) slight staleness set in on the controlbread two days later than it did for the 70-21 - 9bread (6 and 4 days respectively).

According to Axford et al (1968), the rate ofstaling decreases as the loaf volume increases.This could possibly be the reason why in thisstudy, composite bread such as the 7 0 - 2 1 - 9bread with reduced loaf volume tended to stalefaster than the 100% wheat bread although thedifference at room temperature was not significant.

CONCLUSION

It is feasible to combine cassava and wingedbean flour with wheat flour in bread-making.However, the extent to which wheat flour canbe replaced is limited by the absence of glutenin both cassava and winged bean flour.

An increased level of cassava flour in themixture, especially when it exceeds 30%, tendsto produce a weaker dough which is easily ex-tended and possesses a lower amylase activityresulting in poorer carbon dioxide productionduring baking. Up to the extent of 30% incor-poration, cassava flour did not produce a signi-ficantly reduced loaf volume and specific loafvolume, and its organoleptic characteristics wereas acceptable as the 100% wheat bread. In the70-30% bread, however, the protein content wasreduced to 10.2% as compared to 14% in thecontrol (Table 7). Supplementation with wingedbean flour, however, reestablished the breadprotein. In the case of the 70-21-9 breadthe protein content was found to be 13.8%.Nevertheless, it was the 75-20-5 bread which,besides having a comparable protein level of13.2%, also produced acceptable loaf volume,specific loaf volume and organoleptic characteris-tics. The rheological characteristics of its dough,however, as evaluated by the Farinograph,Extensograph and Amylograph did not matchthose of the control bread.

Further study would be necessary to improvesuch characteristics. Tsen and Hoover (1973),for example, have used sodium steoroyl-2 lactylateto increase dough stability of soya-wheat bread.Potassium bromate and ascorbic acid have alsobeen found to give good loaf volume to cassavawheat bread (Dendy and Clarke, 1969).

14

UNIVERSli

Mean sensory perception s

storage

0

2

4

6

8

X2R

Hedonic scale of the scores

** P <0.01

TABLE 6

jcores of the freshness of the control and 70-21-9 bread for differentat room and refrigerator temperatures

Control

room temp.(26.5-28°C)

5.60

4.38

2.50

1.75

1.13

26.73**

Bread

fridge temp.(ave. 9°C)

5.60

4.50

3.38

2.64

2.00

22.63**

storage periods

70-21-9 Bread

room temp.(26.5-28°C)

5.38

3.50

2.88

1.75

1.50

27.08**

: 6 = very fresh 3 = slightly stale5 = fresh 2 = stale4 — slightly fresh 1 = very stale

Composition of the bread with and

Bread samples

Control

30% cassava flour

Protein3

(%)

13.96

10.16

75-20-5% .wheat-cassava) 13.19and

70-21-9% 1 winged bean ) 13.77

a = %N x 5.7b = by acid hydrolysisc = by calculation

TABLE 7

[ without fortification(dry matter basis)

Fatb

(%)

5.48

4.57

5.99

7.07

as compared to the control

Carbohydrate0

(%)

78.90

83.82

79.08

77.41

fridge temp,(ave. 9°C)

5.38

3.38

2.63

2.25

1.88

23.88**

bread

Ash(%)

1.66

1.45

1.74

1.75

ACKNOWLEDGEMENTS

The authors wish to express their sinceregratitude to the Dean, Faculty of Agriculture,and Head, Department of Food Science andTechnology, Universiti Pertanian Malaysia, fortheir support in this study. Appreciation is alsoexpressed to Dr. A. Zaharuddin, AssistantDirector of M.A.R.D.I, for the use of the facilitiesin A.P.U., M.A.R.D.I. The co-operation ofEncik M. Hashim Hassan, Head, Plant ProductsBranch A.P.U. and his staff is gratefully acknow-ledged. Special thanks are due to Cik ChelviShanmugam for typing this manuscript.

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NG ENG GIM AND KHOR GEOK U N

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(Received 2 March 1978)

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