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Puk. J Agrisc: 1'01. 39(2;,2002

PREPARATION AND APPLICATION OF BREAD IMPROVER USINGLOCALLY AVAILABLE INGREDIENTS

Salim-ur-Rehman, Javaid Aziz Awan, Imran Pasha, Nuzhat Huma, and Amer MumtazDepartment of Food Technology, University of Agriculture, Faisalabad - Pakistan.

Trials were conducted to develop the bread improvers taking weight to volume ratio as response factor which was affected by ascorbic acidand enzyme activated soy flour as independent variables, Calcium sulphate, ammonium chloride, potassium iodate. sodium chloride andstarch were used in the formulation, Wheat and wheat flour contained moisture 8,32% and 13.97%. crude protein 13.48% and 13.07%,crude fat 2.34% and 1.40%, crude fiber 3.54% and 1.78%, total ash 1.45% and 0.81(~/o and NIT 70,87% and 68.97% respectively.Response surface methodology was used to optimize the effect of independent variables, Sensory evaluation of bread containing variousimprovers revealed that bread characteristics improved as a result of variation in these ingredients. Results of contour plots for weight tovolume ratio, volume and grain texture of bread revealed that good quality bread could be produced with flour containing 0.5% newlydeveloped improver. Maximum response was found with ascorbic acid in the range of 0,16-0.20% and soy flour from 18.71-22.85%.Farinographic characteristics such as water absorption, dough development t ime, resistance of dough and tolerance i ndex also improved as aresult of the addition of Improver.Key words: Improver, bread, ascorbic acid, soy flour, response surface, farinograph.

INTRODUCTIONWheat flour is an important milled product of wheat which is usedfor bread production. Composition and nutritive value of wheat

flour modulate widely due to factors like class, variety, soil.weather conditions and cultural practices. These factors in turnaffect water absorption. mixing time and loaf volume of bread(Kent. 1983). Moreover, small baking plants often face problemswhile using the flour of varying characteristics for bread production(Chaudhry. 1991).The quality of bread can be enhanced by using bread improvers indough which are very beneficial for the production of quality bread

by baking industry (Matz, 1960). Optimization of bread improversis of vital importance in maintaining bread of standard qualitywhich can be achieved by applying response surface methodology(RSM). RSM uses the quantitative data to determine andsimultaneously solve multivariate equations that specify theoptimum product for a specified set of factors through mathematicalmodels (Giovanni, 1983). It is also more efficient than traditionalexperimental procedures as it decreases both time and cost required

to determine the optimum product ( Khuri, 1992).The RSM technique has been applied successfully in thedetermination of oxidative requirements of no time dough (Baker etal.. 1988), optimization of Chinese wet noodle formulation (Shelkeet al., 1990) and in the production of enhanced nutritional valuesavoury chapaties (Rehman et al., 1996).At present. a number of commercial bread improvers are importedin Pakistan. This incurs expenditure of precious foreign exchange,A need has been justified to prepare a bread improver from localingredients to meet the requirements of local baking industryconsidering the properties of domestic wheat. This paper is an efforttowards this direction.

MATERIALS AND METHODSWheat variety Punjab-96 was collected from Ayub AgriculturalResearch Institute, Faisalabad. The sample was cleaned byremoving extraneous materials manually.

Tempering and milling of wheatThe cleaned wheat was tempered by adding appropriate amount ofwater to raise the moisture content to 14 %. The wheat was

conditioned in batches of 2 Kg by placing each one in air tight plastic containers. The amount of water required was calculated byusing the formula described in the AACC (2000). Calculatedamount of water was added to each container, mixed for 5 minutesand allowed to rest for 24 hours in order to distribute the moistureevenly.Milling was done with Quadrumate Senior Experimental Mill toobtain four milling fractions, i.e. high grade flour, low grade flour,shorts and bran. High grade and low grade flours were blended andkept in polyethylene bags for subsequent analyses Shorts and branwere discarded.Chemical analysisWheat and flour were analyzed to determine moisture. crude

protein, crude fiber, crude fat, total ash and NFE according to themethods described in AACC (2000).Ingredients for bread improversSoybean was procured from the local market. After cleaning. it was

soaked in water for 2 hours and spread on gunny - sacks. It wasallowed to sprout for 18 hours. Sprouted soybeans were sun-driedand milled to get enzymatically active soy flour. Analytical gradechemicals i.e. calcium sulphate. ammonium chloride, potassiumiodate, sodium chloride and ascorbic aeid were procured from alocal scientific store.Formulation of bread improverThe following basic formulation for bread improver preparation has

been adopted (Matz, 1960). Starch was partially replaced byenzymatically active soy flour and ascorbic acid as determined byRSM model.Ingredients (YoageCalcium sulphate 24.93Ammonium chloride 9.38Potassium iodate 0.22Sodium chloride 24.93Starch 40.54

100.00

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Optimization of bread improverTrials were conducted to get the levels of soy flour and ascorbicacid in the improver. Response surface methodology (MinitabVersion 8.2, Minitab lnc., 308] Enterprise Drive, State College PA1680] -3008, USA) was applied to optimize the bread improver.Calcium sulphate. ammonium chloride, potassium iodate andsodium chloride were taken as constant factors while soy flour andascorbic acid levels were expressed as variable factors. Thefollowing model was fitted.

Table I. Design matrix for two factors with blocks for fittingsecond order response model

BlocksTreatments A B

TI -I -I

T2 +1 -I

1'3 -I +-1T4 +1 +1T5 0 0T5 0 0T5 0 0

T5 0 0

T6 -2 0

T7 +2 0T8 0 -2T9 0 +2T5 0 0T5 0 0

II

-2 -I 0 +1 +2A. Soy tlour (%) 10 15 20 25 30B. Asc. acid (%) 0.05 0.10 0.15 0.20 0.25

Bread preparationBread was prepared by using straight dough method as described inAACC (2000). The loaf volume was determined by rape seeddisplacement method.Sensory evaluation

To asses the sensory quality of bread, the samples were presented toa panel of seven judges after 3, 12, 24 and 36 hours of baking.Scoring was done according to the modified score sheet given byLand and Shephard (I 988) for the sensory characteristics i.e. crustcolour. crust character, crumb colour, grain texture, graintenderness, flavour and taste.Maximum score assigned was 7, corresponding to excellent qualitywhile. minimum score was 1 for extremely poor quality of bread.Technological characteristics of bread improversThe tlours containing bread improvers and control weretechnologically tested by using Brabender Farinogaph according tothe method described in AACC (2000). Statistical analysisThe data relevant to optimization phase was statistically analyzedusing Response Surface Methodology (Minitab,

1991). The data pertaining to sensory evaluation of bread wasstatistically analyzed by using Analysis of Variance Technique(Steel and Torrie, ] 980).

RESULTS AND DISCUSSIONProximate composition of wheat and flourIt is obvious from the data (Table 2) that wheat variety Punjab96

had 8.32% moisture, 13A8~ocrude protein. 1450 total ash, 3.54%crude fiber, 2.34% crude fat and 70.87(~0 nitrogen free extract(NFE).Flour from wheat variety Pb-96 contained 13.97% moisture.13.07% crude protein, 0.8] % total ash, I. 78% crude fiber, IAO%crude fat and 68.97% nitrogen free extract (NFE). These results arenot much different from the previous findings (Ali, 1980; Rehmanet al., 1988; Mahmood et al.. 1989:Siddique. 1989 and Rehman. 1994).Milling performanceThe data on milling fractions is given in Table 3. It was observedthat Pb-96 yielded 43.33% low grade flour. 26A5% high gradeflour, 69.78% total flour, 25.31 % bran and 4.27% shorts. Millingloss was 0.64%. The results on total flour yield are in line with thefindings of Akram (1990) for wheat variety LU-26S and Mahmoodet al. (I 989) where the total flour yield ranged from 69.55-70.98%in some Pakistan wheat varieties.

Table 2. Proximate composition of wheat (Punjab-96) andflour

Composition (%) Wheat variety Flour

Moisture 8.32 13.97

Crude protein (d.b) 13A8 13.07Total ash (d.b) IA5 0.81Crude fiber (d.b) 3.54 1.78Crude fat (d.b) 2.34 lAO

NFE (d.b) 79.19 82.93

d.b.: dry basis

Table 3. Milling performance of wheat (Punjab-96)

Milling Fraction Quantity (%)

High grade flourLow grade flourTotal flourBranShortsMilling losses

26A543.33

69.7825.31

4.270.64

Optimization of bread improverEnzymatically active soy flour serves as bleaching. crumbsoftening and antistaling agent. It provides the bread with finer andtender grains and softer texture (Matz, 1960).Ascorbic acid is a slow acting oxidizing agent. It promotes theoxidation of sulthydral bonds thereby increasing S-S and S-Hinterchanges. These results in strengthening the gluten

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structure and making it more resistant to rough handling and provideshigher loaf volume (Kent, 1983). Keeping in view the properties ofthese two ingredients, these were added to the improver formulation.Response surface methodology was used to optimize the breadimprover containing enzymatically active soy flour and ascorbic acid.The proportion of enzymatically active soy flour ranged from 10-30 %in increments of 5%, while ascorbic acid ranged from 0.05-0.25% inincrements of 0.05 % of the total formulation. Best fitting models weredetermined by regression procedures and used as predictors for thetreatment factors and to estimate the properties of independentvariables. The signs of the regression co-efficient within each equationreveal the direction of the effect of each independent variable, thesquares and interactions (Table 5). The significant F values providedguidelines for model building (Table 4). The R 2 values for the bestfitting models were high (0.95, 0.94) for grain texture (3 h. 36 h),volume (0.68) and weight to volume ratio (0.66) for bread improver.Satisfactory levels of R 2, CV % and model significance indicated goodfit of models with no significant lack of fit. These results are consistentwith previous findings (Shelke et al., 1990).Results regarding contour plots for weight to volume ratio, volume andgrain texture (3 hours and 36 hours after baking) of bread revealed thatsatisfactory bread could be produced from an improver containing18.71-22.85% soy flour and 0.16-0.20% ascorbic acid. Ascorbic acidfrom 50-200 ppm on the basis of flour weight was found to bring aboutgreat change in extensographic characteristics and improvement in

baking quality of Indian commercial wheat flours (Ravi and Rao,1995).Similar findings have been recorded by Kaur et al (1995) with theaddition of 0.5% sodium stearoyl-2-lactylate together with 7.5%enzyme active soy flour.

Table 4. Analysis of variance for evaluation of models for quality parameters of optimally prepared bread improvers

Source F P CV R 2

Weight to volume ratio

Improver 2.29 0.0151 5.70 0.66VolumeImprover 2.48 0.0130 5.71 0.68

Grain textureImprover (3 hI'S) 23.72 0.000 0.82 0.95Improver (36 hrs) 17.71 0.001 1.046 0.94

Sensory evaluationBreads prepared from improvers produced during optimization phasewere evaluated for their sensory characteristics using modified scoresheet of Land and Shepherd (1988). The data on sensory evaluation of

bread are presented in Table 6. It is evident from the table that improver preparations enhanced sensory characteristics like crust colour. crustcharacter, crumb colour, grain texture and grain tenderness. The resultsare in close agreement with the previous findings of Matz (1960),Hussain (1994) and Rehman (1994).

Table 5. Models for selected attributes used in response sufaceoptimization phase

Wt. to volume ratio:

C1 = 4.19 + 0.101 Block 1+ 0.125'

Fact AI 0.149' Fact B - 0.116'

AxA - 0.141' BxB - 0.230' AxB.

Volume:

C2 = 362 + 9.0 Block 1+ 12.4' Fact A I 13.5'

Fact B - 10.2' AxA - 12.9' BxB - 19.0' AxB.

Grain texture:

3 hours after bakingC1= 5.50 + 0.0020 Block 1+ 0.114' Fact A .~ 0.0617

Fact B - 0.104' AxA - 0.104' BxB - 0.0200' AxB 36

hours

Cr 5.46 + 0.0420 Block 1-+ 0.1 14' Fact At 0.0775 Fact B -

0.104' AxA - 0.112' BxB - 0.0175' AxB-----------------------_.- -

A non-significant effect was observed in the taste and flavour of bread

due to improver addition. 1'4, 1'5, and 1'7 scored higher than other

treatments.

Farinographic characteristics

The improver preparations produced during optimization phase were

technologically studied usmg Brabender Farinograph. The results are

presented in Table 7. It is obvious from the data that water absorption

capacity. arrival time and dough development time increased with the

addition of bread improvers. Water absorption ranged from 58.8% in

control (TO) to 61.4% in 1'4, arrival time increased from I min. in

control (TO) to 4.5 min. in 1'3, while dough development time

accentuated from 3.5 min. in control (TO) to 5 min. in 13. 15. 1'6, 1'8 and

1'9. The increase in all the characteristics is primarily due to elevation in

protein content by soy addition in the improver formulations. The results

are in harmony with the previous findings of Sathe et al (1981) and U

Ilah ( 1990). Dough stability ranged from 3.0 min. in control (TO) to 6.5

min. in 1'1 and 1'7. It might be attributed to the addition of

enzymatically active soy flour into the improver as reported b) Shah et

al (1986).

Resistance of dough increased from 4.0 min. in control to 9.5 (min.) in

1'5 and 1'6. It might be due to increase in flour strength owing to

improver addition (Siddique, 1(89). Softening of dough ranged from 80

BU in control to 120 BU in 1'2, 1'3, 1'4, 1'6 and 1'8. It might be

attributed to arnylolyticchanges due to sprouting of soybean. Khalid el

al., (1992) reported an increase in dough softening due to sprouting of

wheat. Tolerance index increased from 20 BU in control (TO) to 40 BU

in 1'4, 1'5, 1'6 and 1'9. Kaur et al (1995) reported an increase in mixing

tolerance owing to enzymatically active soy flour into wheat flour.

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Table 6. Table of Means showing the effect of bread improver preparations on sensory characteristics of bread.

Cha racteristics TO T1 T2 T3 T4 T5 T6 T7 T8 T9Crust colour 5.3h 5.5f 5.7c 5.6e 5.8a 5.75b 5.4g 5.77b 5.6e 5.7cCrust character 4.87i 4.99h 5.19f 5.15g 5.4cd 5.49a 5.2ge . 5.46b 5.38a 5.32cGrain texture 5.05i 5.14f 5.29d 5.21e 5.4lc 5.58a 5.06h 5.46b 5.llg 5.4c

Grain tenderness 4.93h 5.23f 5.28e 5.22f 5.42c 5.57a 5.18g 5.46b 5.24f 5.36dTO= Control

TI= Improver containing 15% soy flour + 0.10% ascorbic acidT2= 25% + "T3= 15% +0.20% "T4= 25% + "T5= 20% +0.15% "T6= 10% +T7= 30% + "T8= 20% +0.05% "T9= 70% +07')% "

Table 7. Farinographic characteristics of bread improvers

Treatments WA AT DS RD DO SD

(%) (min) (min) (min) (min) (BU) (BU)TI

TO 58.8 1.0 3.0 4.0 3.5 80 20TI 59.4 1.0 6.5 7.5 4.5 80 20T2 60.0 1.75 6.25 8.0 4.0 100 30T3 60.2 4.50 4.0 8.5 5.0 120 30T4 61.4 3.0 5.5 8.5 4.7 120 40T5 60.2 4.0 5.5 9.5 5.0 90 40T6 59.6 3.5 6.0 9.5 5.0 120 40T7 61.2 2.5 6.5 9.0 4.7 90 30T8 59.2 3.7 4.3 8.0 5.0 90 20T9 61.2 3.0 6.0 9.0 5.0 100 40

WA: Water AbsorptionDS: Dough StabilityDO: Dough DevelopmentTI: Tolerance IndexBU: Brabender Unit

A T: Arrival TimeRD: Resistance of DoughSO: Softening of Doughmin: minute

CONCLUSION:

Comparing weight to volume ratios of bread prepared from localimprovers and commercial improvers, it is concluded that T4(improver B containing 25% enzymatically active soy flour and0.2% ascorbic acid) and T5 (improver B containing 20%enzymatically active soy flour and 0.15% ascorbic acid) are quitecomparable with commercial improvers. It is concluded thatsatisfactory bread can be produced from an improver containing18.71 - 22.85% soy flour and 0.156 - 0.200% ascorbic acid.LITERATURE CITEDAACC. 2000. Approved Methods of American Association of

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