EFFECT OF BARLEY FLOUR BLENDING ON FUNCTIONAL, BAKING AND ORGANOLEPTIC CHARACTERISTICS OF HIGH-FIBER...

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EFFECT OF BARLEY FLOUR BLENDING ON FUNCTIONAL,BAKING AND ORGANOLEPTIC CHARACTERISTICS OF

HIGH-FIBER RUSKS

MAHESH GUPTA1,2, AMARINDER SINGH BAWA2,3 andANIL DUTT SEMWAL1,2

1Cereal and Pulses Technology Division

2Defence Food Research LaboratorySiddhartha Nagar

Mysore-570011, India

Accepted for Publication April 29, 2009

ABSTRACT

Barley flour was incorporated into wheat flour at 0, 10, 20, 30 and 40%substitution levels for the preparation of high-fiber rusks. The gluten contentand sedimentation value of the prepared rusk samples and the mixing time ofthe dough decreased while water absorption capacity increased with increasein the level of barley flour incorporation. Protein and glutelin contentsdecreased significantly on blending of barley flour to wheat flour. The rusksprepared from the blends also varied in their loaf weight, loaf volume andsensory characteristics. The rusk volume decreased with increasing amount ofbarley flour substitution. The color of rusks changed from creamish white todull brown and a gradual hardening of texture was observed as the addition ofbarley flour increased. At the higher levels, the acceptability declined becauseof the compact texture of the crumb and the strong flavor of the product. Theaddition of 20% of barley flour to wheat flour produced acceptable rusksshown by sensory scores.

PRACTICAL APPLICATIONS

The present investigation relates to the use of barley flour incorporation inbakery product, such as rusks. Rusk is widely consumed in all countries; wheatflour is the main flour used, and the baking procedure includes mixing, fer-mentation, baking and roasting. At the present time, in India and also allaround the world, there is an increased consumer demand for whole grain, and

3 Corresponding author. TEL: +91-821-2472953; FAX: +91-821-2473468; EMAIL: [email protected]

Journal of Food Processing and Preservation 35 (2011) 46–63.46 DOI: 10.1111/j.1745-4549.2009.00446.x

© 2009 Wiley Periodicals, Inc.

mixed grain baked products. Many consumers prefer products rich in fiber andhave more health beneficial properties. However, modern consumer interest innutrition and health may help restore barley’s status as a significant componentin the human diet. So, this investigation was undertaken to study the effect ofbarley flour supplementation on the functional, baking and organoleptic char-acteristics of high-fiber rusks.

INTRODUCTION

Barley (Hordeum sativum) is the fourth most important cereal crop in theworld. In India, barley occupies an area of nearly 7.604 lakh hectares with atotal production of 13.30 million metric tons and a productivity of 1,888 kg/ha(http://www.Indiastat.com). It has traditionally been the cereal of choice formalting and brewing because of the type and amount of enzymes produced,whereas only a small proportion is used as animal feed or human food. Barleyis unique among cereals because of its high concentration of soluble dietaryfiber, particularly mixed linked 1-3,1-4 b-D glucans, this material has beenstudied for its hypocholesterolemic effects in animals and humans (Bhatty1986; Hecker et al. 1998; Riaz 1999; Kalra and Jood 2000).

The bakery industry is one of the largest organized food industries allover the world and, in particular, biscuits, cookies, cakes and rusks are amongthe most popular products because of their convenience, ready-to-eat natureand long shelf life. Bakery products of composite flour have manyfold advan-tages, apart from extending the availability of wheat flour, and they are lookedupon as carriers of nutrition (Robbelen 1979). There is a great opportunity foremploying wheat–barley mixtures in programs to improve the diet (Sanchezet al. 1985). Several studies have indicated the possibility of incorporatinghull-less barley (Bhatty 1986), soybean (Rastogi and Singh 1989), sorghum(Rao and Rao 1997; Carson et al. 2000), cowpea (Sharma et al. 1999b) andBengal gram (Rathna and Neelakantan 1995) into wheat flour at various levelsand its rheological and baking properties have been reported.

Barley oat and soybean are grown widely, diversified and used as func-tional ingredients for many food products. Based on nutrient composition andthe importance of dietary fiber in the diet, many attempts have been made touse these as fibrous materials in bakery products (Idouraine et al. 1995). Ruskis widely consumed all countries; wheat flour is the main flour used; the bakingprocedure includes mixing, fermentation, baking and roasting, so therefore,the objectives of this investigation were to study the effect of barley floursupplementation on the functional, baking and organoleptic characteristics ofhigh-fiber rusks and to study the shelf stability of rusks at different temperatureconditions in different packaging materials.

47BARLEY FLOUR HIGH-FIBER RUSKS

MATERIALS AND METHODS

Materials

Barley grain was procured from Punjab Agriculture University, Ludhiana,Punjab (India). Barley grains were conditioned to 14% moisture content.Commercially available wheat grains were procured from the local market(India). The milled wheat and barley grain both was ground to flour in alaboratory centrifugal mill (Model ZM 200, Retsch Gmbh, Rheinische Straße,Haan, Germany), passed through a 60-mesh (British standard-340 microns)sieve, giving a 78% flour yield and were stored in airtight containers until used.Blends of wheat flour and barley flour were prepared by replacing wheat flourwith barley flour at 0, 10, 20, 30 and 40%.

Functional Characteristics

Gluten Content. AACC method No. 10-11 (AACC 1984) was used forgluten estimation in plain and blended flours. The weighed sample (25 g, 14%moisture) was transferred into a clean dry mixing bowl and 13.5 mL of waterwas added. The contents were formed into a stiff dough ball. The dough ballwas dipped into water for half an hour and then washed by hand under tapwater until free from starch. The wet gluten thus obtained was weighed andexpressed in percentage with respect to original flour sample (25 g). The wetgluten was then transferred into a dish and placed in a hot air oven at 100C for2 h. After cooling in desiccator, the dry gluten was weighed and results wereexpressed in percent wet gluten present in the samples.

Sedimentation Value. The sedimentation value in plain and blendedflours was determined according to the procedure given by Misra et al. (1998).The weighed samples of prepared rusks were ground into powder in pestlemortar (5 g) and were transferred into a 100-mL stoppered graduated cylinder.Distilled water (50 mL) was added and the cylinder was shaken horizontallyfor 15 s. The contents of the cylinder were again shaken for 15 s at 2- and4-min intervals. Immediately after the last shake, 50 mL of sodium do-desyl-sulfate-lactic acid reagent was added and mixed by inverting the cylinder fourtimes. Inversion was repeated four times at 6, 8 and 10 min intervals. Thecontents of the cylinder were then allowed to settle for 20 min before thesedimentation values were read and expressed in milliliters.

Water Absorption Capacity. Water absorption capacity was assessedby the method of Quin and Paton (1983). To estimate water absorption capac-ity, 5 g samples of prepared rusks were ground into powder in pestle mortar

48 M. GUPTA, A.S. BAWA and A.D. SEMWAL

and transferred in a 50-mL centrifuge tube. Thirty milliliters distilled waterwas added and stirred with a glass rod for 5 min. After allowing the contentsto stand for 30 min, at ambient conditions, it was then centrifuged (Model R24, Remi Instruments, Mumbai, India) at 11,000 g for 25 min. The volume offree liquid was measured and the retained volume was expressed as milliliterof water absorbed per gram of sample, on a dry basis.

Mixing Time. The dough properties of the composite flours were deter-mined at 65% water absorption using a 10-g direct drive recording sensor ofmixograph (National Manufacturing Division, TMCO, Lincoln, NE) accordingto standard AACC procedure 214, effect of blending on bread-making charac-teristics No. 54-40 (AACC 1984). Mixing time is the time when all the flourcomponents have been hydrated and, thus, the height of the mixing curve grad-ually increases to peak dough. To reach the optimum development, differentflours require different work inputs to mix the dough. From the mixogram curve,the time to reach maximum height (dough development time) was measured.

BAKING CHARACTERISTICS

Baked Rusk Formula and Preparation

Rusks were formulated and prepared according to Yaseen (2000). The ruskformula for each loaf included 100 g flour (14% moisture), 1.5 g dry yeast, 1.5 gsalt, 5 g sugar, 3.0 g vegetable oil, 2.0 g fennel (Foeniculum vulgare) and anadequate amount of water to obtain dough of optimum consistency. Floursamples and all ingredients were mixed in Hobart mixer (Model N50, Hobart,Edmonton, Alberta, Canada). Dough was kneaded until reaching to maximumconsistency (10–12 min), and then it was left for 20 min for resting. Dough wasdivided into pieces of 150 g (as pan capacity), then it was mechanically moldedand put in pan. Pan was left in the fermentation chamber (National Manufac-turing Company, Lincoln, NE) for 90 min at 32 � 1C and 85% relative humid-ity and then was baked in a revolving reel oven (National ManufacturingCompany, Lincoln) at 220 � 1C for 25 min. The loaves were allowed to cool onracks for about 30 min, then were put in a refrigerator at 5C for about 2 h andthen were mechanically sliced to about 1 cm thickness. The sliced pieces wereroasted at 200C for 15 min. Due to inferior handling properties of formulascontaining high level of fiber, slicing the baked dough after 2 h or more periodof refrigeration at 5C was recommended during preparation.

Loaf Volume and Loaf Weight

Rusks from control and supplemented flours were baked in triplicatesamples. After removing from the oven, loaves were immediately weighed and


then placed on a wire grid for about 2 h before the volumes were determined.Loaf volumes were measured by the rapeseed displacement method. Specificloaf volumes were calculated by dividing the loaf volume by the loaf weightand expressing the results as milligram per gram.

Total Protein and Protein Fractions

The protein contents of the blends were determined by the micro-kjeldahlmethod No. 14.026 (AOAC 1995). The different protein fractions viz. albumin(water soluble), globulin (salt solution), prolamin (alcohol soluble) and glute-lin (alkali soluble) were determined according to the modified method of Naik(1968). Also, 5 g of prepared rusks sample ground into powder in a pestlemortar was suspended in distilled water (25 mL) and shaken for 1.5 h in anEnviron-shaker (Model 3527-1CC, Lab-line Instruments Inc. Melrose Park,IL). The suspension was centrifuged (Model R 24, Remi Instruments) at8,000 g for 15 min and the clear supernatant was collected. The extraction wasrepeated twice and the supernatant was pooled. This represented the albuminfraction. Salt-soluble proteins were prepared in a similar manner by extractingthe residue (left after extracting the albumin fraction) with 1% w/v NaClsolution. The alcohol-soluble prolamin fraction was prepared by intermittentlyshaking the residue left behind after the extraction of globulin with 60%ethanol for 2 h. The supernatant was collected after centrifugation. The residueobtained after prolamin extraction was extracted with 0.4% NaOH solution byshaking for 2 h and centrifuging at 8,000 g for 15 min. The supernatant col-lected after repeated washing of residue with 0.4% NaOH represented theglutelin fraction. The nitrogen content in the protein fractions was determinedby the micro-kjeldahl method no. 14.026 (AOAC 1995).

Chemical and Nutritional Properties

Moisture, protein and fat contents were measured according to the Asso-ciation of Official Analytical Chemists (AOAC 1998). b-glucan was deter-mined using the method of Aastrup and Jorgensen (1988). All analyses werethe means of three replicates. Mineral matters were evaluated by using atomicabsorption spectrophotometer (AAS), as ashing of the rusks sample was donein muffle furnace (AOAC 1998). Then, after ashing, 15 mL 3 N HCL wasadded and the crucible was boiled with ash material until it reached 2–3 mL,then the volume was made up in volumetric flask to 50 mL. Mineral contentwas estimated by AAS (AAS Vario6, Analytik Jena AG, Jena, Germany) byflame mode and results were in mg/100 g of samples. Color values weredetermined using Chromaflash tristimulus colorimeter; color values L*, a*, b*and DE as measures of lightness, redness–greenness, yellowness–blueness andoverall color difference, respectively, were recorded for each sample andcompared with a standard.


Textural Properties

The fracture force test was conducted on the rusks using texture analyzer(Llyod Instrument Ameket Inc., TA Plus, Fareham, Hampshire, U.K.) andconducting a “measure force in compression” test with a sharp blade cuttingprobe. The analyzer was set at a “return to start” cycle with a speed of 1 mm/sand a distance of 3 mm. A force/penetration distance plot was made for everytest. Hardness and brittleness of the rusks can be estimated by the maximumforce (N) and the mean slope (N/s) of the force/deformation curve, respec-tively. Puncture test was performed with 2 mm probe with a speed of 1 mm/sand distance of 5 mm.

Organoleptic Characteristics

A panel of 10 judges evaluated the organoleptic characteristics of pre-pared rusks. They assessed crust color, appearance, flavor, texture, taste andoverall acceptability, using a 9-point hedonic rating scale ranging from likeextremely (9) to dislike extremely (1) for each characteristics, as suggested byAustin and Ram (1971). Sensory evaluation was done by 10 judges in the agegroup of 20 to 50 years, comprising of professional, student and consumers.

Packaging and Storage

Following packaging materials were procured from the reputed manufac-turers and used for packing of rusks: (1) Paper (45 GSM)-Al. foil (20 m)-polyethylene (37.5 m) laminate (PFP). (2) 12 m Met. PET (2.9 OD) LD/LLD –75 m (Met.Pet.). Cookie samples were stored at room temperature (26C) andhigher temperature (37C). It was analyzed initially and at regular intervals forvarious physical and chemical parameters. During the investigation, sensoryevaluation and various physical and chemical parameters like moisture, per-oxide value (PV), free fatty acids (FFAs), thiobarbituric acid (TBA) value andmicrobiological analysis were carried out. PV was estimated by the methods ofAOCS (1973). FFA was determined according to AOCS methods (1973). TBAvalue in food samples was determined by the method of Tarledgis et al. (1960).

Microbiological Analysis

Microbial analysis of rusks was determined according to the method ofHarrigan and Mccance (1976). Total plate count (TPC), coliforms and yeastand mold were enumerated in the samples.

Ten grams of sample was weighed aseptically and transferred to a sterilepestle and mortar. After this, 90 mL of diluent, i.e., peptone water, was addedand macerated. In addition, 1 mL of this solution (10-1) was transferred intotest tubes containing 9 mL peptone water to obtain dilution of 10-2 serial


dilution. One milliliter quantities of these diluents were pipette out into sterilePetri plates. To each plate, molten agars were poured (Violet red bile agar forcoliforms, Plate count agar for standard plate count (SPC) or TPC and Potatodextrose agar for Yeast [acidified with tartaric acid]) in each of the Petri platesand swirled for uniform distribution of the molten agar. The plates wereincubated in inverted position for the requisite period at the appropriate tem-perature (for SPC, 30C for 48 h; for coliforms, 37C for 48 h; and for yeast andmolds, 30C for 72 h). Isolated colonies formed on the plates were counted. Theaverage numbers of colony forming units (cfu/g) from the duplicate plates ofthe same dilution were counted and this figure was multiplied with the dilutionfactor and expressed as cfu ¥ 10n/g of sample (n = dilution factor).

Statistical Analysis

The data were analyzed for Duncan’s multiple comparison using Statis-tica Statsoft ver. 8.0 statistical package (Stat Soft, Inc., Tulsa, OK) at differentsignificant levels (P < 0.05).

RESULTS AND DISCUSSION

Mineral Content and Color Characteristics

As barley flour content increased from 0 to 40% in wheat flour, themineral matters, particularly iron, calcium, sodium zinc and potassiumcontent, were increased and improved the nutritional quality characteristicsof rusks. Iron content was increased from 15.77 to 45.0 mg/100 g, calcium7.99 to 10.73 mg/100 g, sodium 99.2 to 205.4 mg/100 g, potassium 289.5 to431.6 mg/100 g and zinc 4.13 to 22.4.0 mg/100 g (Table 1). The color valuesmeasured by tristimulus colorimeter showed that significant color differences(DE) were observed. Its whiteness decreases and rusks changed to a palegolden color as barley flour was incorporated into wheat flour. DE value variesbetween 45.6 and 51.7 and whiteness value decreased from 18.9 to 14.3%(Table 2).

FUNCTIONAL CHARACTERISTICS

Gluten

Wheat flour exhibited mean wet and dry gluten contents of 29.1 and10.3%, respectively, which changed significantly upon blending with barleyflour. Effect of blending barley flour in wheat to a substitution level up to 40%


(Table 3) showed decreasing trend. Thereafter, a significant reduction in glutencontent with increasing level of barley flour was observed. Wheat flourblended with barley flour at a substitution level of 40% had the lowest wet anddry gluten contents (22.0 and 7.7%, respectively). The dry gluten content is adirect indicator of flour strength and bread-making potentialities. The quantityand quality of gluten is responsible for better gas production and retentioncapacity and forms a cellular network of crumb which imparts desirablecharacteristics to fermented products (Anjum and Walker 2000; Belderok2000). Various researchers have also observed that the contents of wet and dry

TABLE 1.EFFECT OF BLENDING ON CHEMICAL NUTRITIONAL PROPERTIES OF RUSKS

Proximatecomposition (%)

0 10 20 30 40

Moisture 8.2 � 0.1a 8.4 � 0.5a 8.5 � 0.2a 8.6 � 0.4a 8.7 � 0.3aCrude protein 11.3 � 0.6c 10.2 � 0.7b 9.5 � 0.4b 8.9 � 0.8a 8.6 � 0.5aEther extract 13.2 � 0.6a 13.3 � 0.1a 13.6 � 0.3a 13.8 � 0.7a 13.8 � 0.7aAsh 1.2 � 0.1b 1.6 � 0.4a 1.7 � 0.0a 1.9 � 0.6a 2.0 � 0.6ab-glucan 0.4 � 0.2a 0.9 � 0.1a 1.1 � 0.3a 1.7 � 0.4a 1.9 � 0.4aEnergy (kcal/100 g) 419.2 � 1.2a 418.9 � 0.8a 418.8 � 0.6a 420.6 � 1.0a 421.0 � 0.8aMinerals (mg/100 g)

Calcium 7.99 � 0.4c 8.87 � 1.2b 9.11 � 0.7b 10.20 � 0.8a 10.73 � 1.0aSodium 99.2 � 1.8c 111.4 � 0.9b 141.8 � 0.8b 187.5 � 0.7a 205.4 � 1.1aPotassium 289.5 � 0.7d 301.5 � 0.9c 333.4 � 1.5b 381.0 � 1.0a 431.6 � 0.8aIron 15.77 � 0.3d 20.04 � 0.1c 33.31 � 0.4b 36.60 � 0.2b 45.00 � 0.2aZinc 4.13 � 0.7d 11.0 � 1.2c 19.0 � 1.0b 22.9 � 1.2a 22.4 � 0.9a

Mean values with the same letters within the same row do not differ (P > 0.05).Mean � SD of triplicate determinations.

TABLE 2.EFFECT OF BLENDING ON COLOR AND TEXTURAL PROPERTIES OF RUSKS

Barleyflour (%)

Weighta (g) Breakingstrengtha (kg)

Whitenessa

(%)Colordifferencea (DE)

Peak puncturingforce (kg)

0 19.46c � 0.11 4.935a � 0.19 18.90a � 0.04 45.65d � 0.05 4.9d � 0.0610 18.90d � 0.21 4.701a � 0.28 16.60b � 0.08 47.40cd � 0.09 5.3c � 0.1120 19.72b � 0.23 4.587a � 0.21 15.94b � 0.12 47.92c � 0.16 5.6c � 0.0530 19.90a � 0.13 4.021bc � 0.22 14.69c � 0.15 50.03b � 0.18 6.0b � 0.0840 19.72b � 0.15 3.293d � 0.32 14.39d � 0.24 51.72a � 0.22 7.4a � 0.17SEM(�) 0.1 0.12 0.10 0.11 0.12

Values for a particular column followed by different letters differ significantly (P < 0.05).Values are means � standard deviations (a: n = 4, b: n = 10).SEM, standard error of the mean.


gluten decreased when increasing the levels of nonwheat flour in white wheatflour (Rastogi and Singh 1989; Singh et al. 1990; Misra et al. 1991).

Sedimentation Value

The sedimentation test is used to assess the gluten quality and bread-making potential of the flour (Belderok 2000). Wheat flour showed the highestsedimentation value (Table 3). In barley-blended flours, there was a significantdecrease in sedimentation value at 10 to 40% substitution levels. Rastogi andSingh (1989) also stated that as gluten content in blends decreased withincrease in the level of barley flour, the corresponding sedimentation value alsodecreased. Misra et al. (1991) and Sharma (2000) also reported similar valuesin wheat flour and soy–wheat blends.

Water Absorption Capacity

The water absorption capacity of wheat flour was 70%, which increasedupon increasing the levels of barley in the wheat flour (Table 3). The highestvalues were found in barley-blended flours at 40% substitution i.e., 81.11%.But water absorption capacity was 76.73% observed at 20% barley–wheatblends that is optimum for preparation of rusks. This increase might bebecause of more water retention by these blends as compared with wheat flour.Selvaraj and Shurpalekar (1982) also showed that water absorption increasedby about 1% for every 2% increase of protein and fiber content in floursupplements in wheat flour.

Mixing Time

The mixing times of the different blended flours revealed that wholewheat flour dough (control) had the highest mixing time, which decreased

TABLE 3.EFFECT OF BLENDING ON FUNCTIONAL CHARACTERISTICS OF FLOUR AND DOUGH

Flours Wet gluten(g per 100 g)

Dry gluten(g per 100 g)

Sedimentationvalue (mL)

Water absorptioncapacity (%)

Dough mixingtime (min)

0 29.12a � 1.62 10.30a � 0.64 33.11a � 0.25 70.70d � 2.00 3.72a � 0.1310 27.40b � 2.28 9.75b � 1.03 32.14b � 1.00 72.11d � 0.22 3.29b � 0.1420 25.21c � 0.74 9.23c � 0.78 31.10c � 0.50 76.73c � 0.11 3.25b � 0.0630 23.11d � 3.44 8.25d � 0.75 30.00cd � 1.50 78.44b � 0.05 2.95c � 0.1240 22.00d � 1.60 8.00d � 0.89 29.00d � 1.00 81.11a � 0.06 2.86d � 0.04

Values for a particular column followed by different letters differ significantly (P < 0.05).Mean � standard deviation of triplicate determinations.


upon blending with barley flours (Table 4). The decrease in mixing time wasnonsignificant up to 20% blending with barley flour; thereafter, it decreasedsignificantly (P < 0.05) to 2.86 min at the 40% blending level. The doughcontaining barley at the 30 and 40% levels exhibited the lowest mixing times(2.95 and 2.86 min, respectively). This may be because of the blended flourshaving poor quality and quantity of gluten. Similar results were also reportedby Hoseney (1994) and Anjum and Walker (2000).

Protein Fractions

The protein-solubility fractions of the barley, wheat and its blends, shownin Table 5, indicate that the protein content of all of the barley flour blendsdecreased. However, protein content decreased significantly in blends from11.3% (control) to 8.6% (40% barley flour blending level). Albumin content ofblends containing barley flours at all the levels was almost the same as that ofwheat flour. However, in wheat–barley-blended flours at the 20% level,albumin content increased slightly to 1.64 and 1.65%, respectively. Globulin

TABLE 4.EFFECT OF BLENDING ON PROTEIN SOLUBILITY FRACTIONS (PERCENT

DRY MATTER BASIS)

Flours Protein Albumin Globulin Prolamin Glutelin

0 11.3c � 0.60 1.64c � 0.16 1.45a � 0.25 2.98a � 0.20 2.70a � 0.1210 10.2b � 0.71 1.65b � 0.16 1.43b � 0.13 2.96a � 0.14 2.70a � 0.3820 9.5b � 0.44 1.65b � 0.07 1.40c � 0.29 2.90b � 0.24 2.74c � 0.3330 8.9a � 0.81 1.68a � 0.15 1.36d � 0.18 2.85c � 0.27 2.72b � 0.1440 8.6a � 0.51 1.68a � 0.10 1.36d � 0.29 2.80d � 0.46 2.72b � 0.14


TABLE 5.EFFECT OF BLENDING ON BAKING CHARACTERISTICS OF RUSKS

Rusksamples

Loaf weight(g)

Loaf volume(mL)

Specific loafvolume (mL/g)

0 160.00d � 2.00 519.00a � 2.00 3.24a � 0.0210 160.50d � 0.50 514.00b � 3.00 3.21a � 0.0220 164.00c � 1.00 503.00c � 4.00 3.07b � 0.0430 166.00b � 1.00 499.00d � 2.00 3.00c � 0.0040 168.50a � 0.50 495.00d � 1.00 2.95d � 0.00



content was found to be highest in wheat flour rusks as control. Prolaminecontents of the various blended flours did not have significant changes com-pared with wheat flour, whereas the glutelin content in barley-blended flour atall the levels did not change significantly. At the 20% level, glutelin content(2.74) was higher in barley-blended flours (Table 4).

BAKING CHARACTERISTICS

Loaf Weight

The loaf weight of the control rusks did not change significantly upto 10% level of substitution of wheat flour with barley flour (Table 5).However, a significant (P < 0.05) increase in loaf weight was observedwith each increment of nonwheat flour, indicating that an extra amount ofwater was retained in breads after baking (Dreese and Hoseney 1982; Raoand Hemamalini 1991). The loaf weight was highest in barley flour-supplemented rusks up to 40% level. The loaf weight increases with increas-ing levels of barley flour that might be because of less retention of gas in theblended dough, hence providing denser rusk texture. The results in this studywere comparable with those reported by earlier workers (Ereifej and Shibli1993; Sharma and Chauhan 2000).

Loaf Volume

A significant reduction in loaf volume was observed as the level ofsubstitution with barley flours increased (Table 5). The highest reduction inloaf volume was in rusk made from wheat flour blended with barley flour at the40% level (Table 6). This reduction in loaf volume was 519 mL in control levelto 495 mL in 40% barley flour blending level. It could be that a dilution effect

TABLE 6.EFFECT OF BLENDING ON SENSORY QUALITY OF RUSKS

Barleyflour (%)

Color Texture Taste Flavor Appearance Overallacceptability

0 8.0a 8.1a 8.0a 8.0a 7.0d 8.0a10 8.1a 8.1a 8.0a 8.0a 7.5c 8.1a20 8.2a 8.0a 8.0a 8.1a 8.5a 8.1a30 7.9a 7.5b 7.5b 7.5b 8.0b 7.8b40 7.2b 7.1c 7.0c 7.0c 7.0c 7.0c

Mean values with the same letters within the same column do not differ significantly (P > 0.05).A 9-point hedonic scale with 1 = dislike extremely and 9 = like extremely was used.


on gluten with the addition of nonwheat flour to wheat flour and less retentionof CO2 gas caused the depression in loaf volume (Sharma and Chauhan 2000).Similar values to those shown in Table 6 for loaf volume were reported byEreifej and Shibli (1993) in whole wheat fermented products. Another reasonfor the decrease in loaf volume could be the presence of relatively highconcentrations of low molecular weight thiols, especially reduced glutathione,which activates proteolytic enzymes, thereby causing a detrimental effect onloaf volume (Indrani and Rao 1992).

Specific Loaf Volume

Specific loaf volume was obtained by dividing the loaf volume by theloaf weight, and results (Table 5) indicated a decrease in specific loafvolume on increasing levels of nonwheat flours (i.e., barley) compared withthe control (Table 6). The poor quality and quantity of gluten in cereal–pulse-blended fermented products may be responsible for retention of CO2gas in the fermented dough and low specific loaf volume. Similar observa-tions have also been reported by Indrani and Rao (1992) and Ereifejand Shibli (1993) in breads prepared from wheat flour. Specific loafvolume of all blends followed the same trend as that of loaf weight and loafvolume.

Organoleptic Characteristics

The blending of wheat flour with barley at different levels altered theorganoleptic properties of different blended rusks. Data on crust color, appear-ance, flavor, crust texture, taste and overall acceptability are presented inTable 6.

Crust Color

As the level of barley was increased in blends, the crust color of thebreads changed from creamy white to dull brown. However, no significantdifference was observed in crust color up to 20% blending with nonwheatflours. Thereafter, a significant difference in crust color was observed in all theblended rusks. The data suggest that the darkest color was observed in rusksprepared from wheat–barley-blended flours by more than 20%. The darkercrust color may be because of the greater amount of fiber-rich barley flour andthe Maillard reaction between reducing sugars and proteins (Raidi and Klein1983).


Appearance

The appearance score for the control rusks decreased significantly uponincreasing the blending level to 10 and 20% with barley. The appearance scorewas in the category of like moderately. Among the blended rusks, the highestappearance score was observed for barley-blended rusk at the 20% level,whereas the lowest score was observed for barley flour-blended rusk at 40%level. Gayle et al. (1986) and Hoseney (1994) suggested that the appearance ofbaked products was an important sensory characteristic on which the accept-ability of product depends.

Flavor

Results for the flavor of the rusks revealed that the flavor score increasedslightly with the increasing level of barley flour up to the 20% level and,thereafter, it decreased. The flavor of barley-supplemented rusks did not differsignificantly up to the 20% level. The flavor of barley-blended rusks might beaffected by the fibrous flavor of barley flour. A similar decrease in the flavor ofbreads with increase in the supplementation levels of fenugreek flour was alsonoticed by Sharma and Chauhan (2000).

Crust Texture

The crust texture was related to the external appearance of the rusks, i.e.,smoothness or roughness of the crust. Crust texture score also decreased withincrease in the substitution of barley in wheat flour as compared with thecontrol sample. Among the blended rusks, the highest score was observed forrusk containing barley flour at the 20% substitution level. The deterioration inthe crust texture of breads with puffed Bengal gram beyond a 20% substitutionhas also been observed (Rathna and Neelakantan 1995). Similar deteriorationin the texture of wheat bread on supplementation was observed by otherworkers (Sharma et al. 1999a; Carson et al. 2000).

Taste

Taste evaluation suggested that control and various supplemented ruskshad most satisfactory taste scores up to the 20% level. Results indicated thatthe taste score decreased with increased level of substitution with barley flouras compared with control sample. Wheat flour substituted with barley flour ofmore than 20% level was rated poorest in taste possibly because of thedifferent flavor of flour blends (Rastogi and Singh 1989).

Overall Acceptability

The overall acceptability rating was the mean score of all the organolepticcharacteristics in the present study. The results showed that the overall accept-


ability score of all the supplemented rusks at the 20% level was at par with thecontrol. Rusks made from wheat and barley flour up to the 20% level werefound acceptable, but at more than 20% substitution, the overall acceptabilityscore was significantly reduced as compared with the control. In overallprofile, the flavor of the rusks was malty and fibrous at the 30 and 40% levelsof substitution. The rusks became tender with increase in the level of barleyflour, which is at par with the texture measurements. Based on the aboveresults, rusks containing 20% barley flour were found to be most acceptable bythe sensory panelists.

Storage Stability

The prepared samples of 0,10, 20, 30 and 40% barley-incorporated ruskswere packed in (1) Paper (45 GSM)-Al. foil (20 m)- polyethylene (37.5 m)

TABLE 7.EFFECT OF BLENDING ON MICROBIOLOGICAL AND CHEMICAL CHARACTERISTICS

OF RUSKS DURING STORAGE

Parameters Barleyflour (%)

Control(0 M)

PFP Met polyester

1 M 3 M 6 M 1 M 3 M 6 M

PVm eq o2/kg

0 0 1.1 2.5 2.7 0.9 2.8 3.110 0 1.2 2.6 2.9 0.9 2.9 3.220 0 1.1 2.4 2.6 0.8 2.7 3.230 0 1.3 2.8 3.1 1.0 2.9 3.240 0 1.5 2.5 2.8 0.9 2.9 3.2

FFA% oleic acid

0 0.21 0.3 0.6 0.9 0.4 0.6 0.810 0.20 0.3 0.7 0.8 0.5 0.6 0.920 0.21 0.5 0.6 0.8 0.4 0.7 0.930 0.22 0.4 0.5 0.8 0.6 0.6 0.840 0.21 0.3 0.8 0.9 0.4 0.8 0.9

TBAmg MA/kg

0 0.045 0.058 0.074 0.087 0.060 0.071 0.08810 0.047 0.059 0.078 0.089 0.065 0.072 0.08720 0.045 0.057 0.081 0.090 0.064 0.070 0.08630 0.049 0.058 0.074 0.087 0.060 0.071 0.08840 0.045 0.058 0.077 0.088 0.064 0.072 0.088

TPC 0 ND ND 1 ¥ 101 4.1 ¥ 102 ND 3 ¥ 101 4.3 ¥ 102

10 ND ND ND 3.1 ¥ 102 ND ND 3.9 ¥ 102

20 ND ND ND 3.0 ¥ 102 ND ND 2.8 ¥ 102

30 ND ND ND 2.1 ¥ 102 ND ND 2.4 ¥ 102

40 ND ND ND 2.0 ¥ 102 ND ND 2.1 ¥ 102

Coliform 0, 10, 20, 30, 40 ND ND ND ND ND ND NDY&M 0, 10, 20, 30, 40 ND ND ND ND ND ND ND

PV, Polanski value; FFA, free fatty acid; TBA, thiobarbituric acid value; TPC, total plate count; Y&M,yeast and mold; ND, not detected.


laminate (PFP), (2) 12 m Met. PET (2.9 OD) LD/LLD – 75 m (Met.Pet.). Theserusk samples were stored at room temperature (26C) and higher temperature(37C). It was analyzed initially and at regular intervals for sensory, chemicaland microbiological parameters up to 6 months. The results showed that PVincreased from 1.1 to 3.1 meqo2/kg in PFP and 0.8 to 3.2 meqo2/kg in met-polyester during storage of up to 6 months. FFA increased from 0.3 to 0.9%oleic acid in PFP and 0.4 to 1.0% oleic acid in met-polyester during storage ofup to 6 months. TBA value increased from 0.057 to 0.090 mgMA/kg in PFPand 0.060 to 0.088 mgMA/kg in met-polyester during storage of up to 6months as shown in Table 7. The prepared samples were also investigated fortheir microbiological stability. The results showed TPC, coliform, yeast andmold not detected during storage of up to 6 months both in PFP and met-polyester packaging material and both at room temperature (26C) and highertemperature (37C) (Table 7).

CONCLUSIONS

Whole barley flour as a good source of fiber and minerals seems to besuitable for the preparation of rusks. The study also concluded that the substi-tution of barley flour into wheat flour up to 20% produced acceptable rusks withgood organoleptic characteristics and also increased fiber content, calcium,iron, zinc and became golden yellow in color.As barley and wheat flour blended,rusks showed high sensory scores and gave antistaling effect during storage ofup to 6 months. It became safe chemically and microbiologically after 6 monthsof storage at different packaging materials at different temperatures.

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EFFECT OF BARLEY FLOUR BLENDING ON FUNCTIONAL, BAKING AND ORGANOLEPTIC CHARACTERISTICS OF HIGH-FIBER...

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