Use of Guar Gum and Gum Arabic As Bread Improvers for the Production of Bakery Products from Sorghum Flour

Food Sci. Technol. Res., +- (),. -,1ῌ --+ , ,**1

Use of Guar Gum and Gum Arabic as Bread Improvers for the Production of Bakery Products from Sorghum Flour

+++,῍ Abd Elmoneim O. ELKHALIFA , Ashwag M. M OHAMMED , Mayada A. M USTAFA and Abdullahi H. El T INAY

+ School of Family Sciences, Ahfad University for Women, Omdurman, Sudan , Department of Food Science and Technology, Faculty of Agriculture, University of Khartoum, Shambat, Sudan

Received October1 , ,**0 ; Accepted May ,0 , ,**1

A low tannin sorghum cultivar (Tabat) was used in this study. Sorghum unlike wheat does not contain gluten. It is a potential cereal for people su# ering from Celiac disease. For preparation of bakery foods mainly bread the elasticity conferred by gluten in wheat is substituted by the addition of guar gum and gum Arabic. Hence, the objectives of this work were: functional properties of sorghum ﬂours treated with guar gum and/or gum Arabic with intention of manufacture of bakery products. Functional properties considered were protein solubility, least gelation concentration, bulk density, water and oil binding capacity, emulsifying activity, foaming capacity and Farinograph characteristics. Treated samples in general were lower than untreated sorghum except for the bulk density and foaming capacity. The results indicated that acceptable bakery products e.g. bread and pizza could be obtained using+ῌ (w/w) guar gum with-2ῌῌῌ (w/w) gum Arabic and * . / (w/w) guar gum with -2 (w/w) gum Arabic, respectively.

Keywords: Guar gum, Gum Arabic, Sorghum ﬂour, Functional properties, Bakery products

Introduction control spread chility in prepared icings (Sabah Elkhier, Sorghum is a crop that is widely grown all over the+333 ). world for food and feed, it is the one of the main staples Gum Arabic is a dried gummy exudation obtained from for the world poorest and most insecure people, it is a key the stems and branches ofAcacia Senegal trees. It is used staple in many parts of the developing world, especially in bakery and sweet roll glazing between,/ῌ ῌ as film in the drier and more marginal areas of the semi tropics. forming improver and sugar adhesives. Also, it is used in Celiac disease continues to be a major health problem in bread (-2ῌ concentration) as baking improver, glazing many countries; as a result various e#-/ orts are being made stabilizer, and in soft cakes betweenῌ ῌ as softener and to solve this problem through the introduction of methods water retention agent (The Gum Arabic Company Ltd,,**/ ). for increased utilization of suitable but less popular food- The objectives of this study were: to study the func- stu# s. Recently there has been increased interest in sor- tional properties of sorghum flour treated with guar gum ghum as gluten free cereal to substitute the gluten rich and/or gum Arabic; and to prepare di# erent bakery prod- cereals in diet of people su# ering from Celiac disease ucts using the treated sorghum flour and finally to test (Elkhalifaet al., ,**. ). the acceptability of these products. Improvers are mixtures of foods including additives intended to facilitate or simplify the production of baked Materials and Methods foods to compensate for changes in processing propertiesMaterials A low tannin sorghum cultivar (Tabat), due to fluctuations in raw materials and to influence the obtained from local market of Omdurman was used in quality of baked foods. They are used specifically to this study. The seeds were carefully cleaned and ground improve production methods and the quality of bakery in a hammer mill to pass a screen with sieve opening of*. . products (Wassermann,,*** ). mm and the flour was stored in polyethylene bags at.ῌ C. Guar gum is extracted from the seed of the leguminous Guar gum powder was obtained from the Sudanese Guar shrubCyamopsis tetragonoloba, where it acts as a food and Company Ltd. (Khartoum, Sudan) and gum Arabic water store (LSBU,,**/ ). powder was obtained from the Gum Arabic Company Ltd. In bakery products such as bread, cakes and doughnuts, (Khartoum, Sudan). Yoghurt was obtained from the local guar gum is used to improve mixing and recipe tolerance, market (Khartoum, Sudan). to improve product shelf life through moisture retention,Protein solubility Protein solubility was determined to prevent syneresis in frozen foods and pie fillings, and to in the pH range of++,ῌ , a one-gram sample was dispersed in0* ml-distilled water and the pH was adjusted with ῍ To whom correspondence should be addressed. NaOH or HCl using a pH meter (100 Calimatic, Germany). E-mail: [email protected] The dispersion was continuously stirred in an orbital 328 A. E. O. ELKHALIFA et al. shaker at+/* rpm for , h at -*῏ΐ , C and then centrifugedPreparation of flat bread Flat bread was prepared at, , ***ῐΐ g at -* C for ,* min. The supernatant was col- using the following method: flour (sorghum with or with- lected and the soluble protein was determined by out guar and gum Arabic or wheat flour as a control) Bardford protein assay (Bardford,+310 ). The percentage +**ῌῌῌ (w/w), sugar + (w/w), salt + (w/w), and instant of soluble protein was calculated and plotted against the active dry yeast,+ῌ (w/w) were mixed at low speed for corresponding pH values. minute using a mixer (HTS-/+2 , Chang Yang Machinery, Critical gelation concentration The critical gelation Taiwan). Water was added and mixed for, min at low concentration was determined by the method of Co# man speed the optimum amount of water was determined and Garcia (+311 ) as modified by Akuber and Chukwu using the formula which is based on preliminary experi- (+333 ) using flour concentrations of ,.02+*ῌῌῌῌ,,,, ῌ ,ment(baking absorption ( ῌ )ῑ῎ ,**/30 . ῐ optimum water +,ῌῌῌῌ,,,,and +. +0 +2 -* ῌ(w/v). absorption from the Farinograph). The mixing speed was Bulk density Bulk density was determined by the then adjusted to medium for. min, after the first bulk method of Wang and Kinsella (+310 ). Ten grams of the fermentation at -*ΐ C and 2/ῌ relative humidity (RH); the tested flour were placed in a,/ mL-graduated cylinder and dough was divided into pieces of0* g, rounded by hand, packed by gentle tapping of the cylinder on a bench top, covered and allowed to relax for+/ min in the fermenta- ten times, from a height of/2ῌ cm. tion cabinet. Dough pieces were flattened by hand and Water- and oil-binding capacity Water and oil bind- cross-sheeted (*2 . mm thickness). All sheeted dough were ing capacity were determined by modified method of Lin placed on a wooden board and transferred into the pro- et al. (+31. ), two grams of each flour sample were weighed ofing cabinet at-*ΐ C and 2/ῌ RH for -* min. The proofed into a pre-weighed centrifuge tube and,* mL of distilled pieces were put on a preheated aluminum tray and baked water were added. For oil binding,* mL of sunflower oil at .,/ΐ C for +** s. Loaves were cooled for +/ min and were vortexed and allowed to stand for-* min at -*῏ΐ , C wrapped in polyethylene bags, then kept at room temper- before being centrifuged at. , ***ῐΐ g at -* C for ,/ min. ature for + h. Excess water or oil was decanted by inverting the tubesPreparation of pizza Pizza was prepared as follows: over absorbent paper and samples were allowed to drain.+** g flour (sorghum with or without guar and gum The weights of water and bound oil were obtained by Arabic or wheat flour as a control),,+ g yeast and g salts di# erence. were mixed and-* g of yoghurt were added to the dry Emulsifying activity and stability The method of ingredients with continuous mixing. The dough was Yasumatsuet al. (+31, ) was used. Emulsions were pre- divided into pieces and it was placed in fermentation pared with one gram of each sample,/* mL of cold distilled cabinet at-*ΐ C for ./ min. The pieces were baked in a water (./*ΐ C) and mL of corn oil then dispersed in a Waring preheated oven at,/*ΐ C for / min. After / min the pieces blender; a clear emulsification was achieved at this tem- were removed from the oven for topping of olive, ketch- perature. Each blended sample was divided equally into up, cheese, green pepper. Pieces were returned to the oven /* ml centrifuge tubes. One centrifuge tube was directly for another+* min. centrifuged at. , ***ῐΐ g at -* C for +* min while the otherSensory evaluation Evaluation of di # erent products was centrifuged under the same conditions after heating (bread and pizza) for various sensory characteristics (ap- in a water bath at2*ΐ C for -* min and cooling to room pearance, colour, taste, food texture and flavour) was temperature-*῏ΐ , C. The height of the emulsified layer, carried out by a panel of ten judges (males and females of as percentage of the total height of material in the un-,*ῌ -/ years old). heated tubes, was used to calculate the emulsifying activ-Statistical analysis For each experiment five repli- ity and stability, respectively, using the following formulae: cates were considered. Means were obtained from two replicates that have good reproducibility and statistically Emulsion activityῌ῍ῌ analysed by analysis of variance (ANOVA) (Snedecor and Height of emulsion layer Cochran,+321 ) and by Duncan multiple range test with a ῑῐ+**. Height of whole layer probability (pῒ* . */ ) (Duncan, +3// ).

Results and Discussion Emulsion stabilityῌ῍ῌ Protein solubility profile Protein solubility character- Height of emulsion layer after heating istics are influenced by factors such as origin, processing ῑῐ+**. Height of whole layer conditions, pH, ionic strength and presence of other ingredients (Kinsella,+313 ). The protein solubility profiles at Foaming capacity The foam capacity was deter- various pH values (++,ῌ ) of sorghum treated with guar mined by the method of Narayana and Narsinga Rao gum and gum Arabic are shown in Fig.+ . The addition of (+32, ) using two grams of sorghum flour samples. guar gum did not alter the protein solubility of sorghum Mixing characteristics The mixing characteristics of flour. Sorghum flour was reported to have minimum wheat flour (control) and the di# erent samples of sor- protein solubility at pH. highest solubility occurred at ghum with or without guar and gum Arabic was deter- pH+, (Elkhalifaet al., ,**. ). Treatment with * . /ῌ (w/w) mined with the Farinograph according to AACC Ap- guar gum,+-2ῌῌ (w/w) guar gum, (w/w) gum Arabic, proved Method/.ῌ ,+ ( ,*** ). combination of*/ .ῌῌ (w/w) guar gum and -2 (w/w) gum Gums as Improvers for Bakery Products from Sorghum 329

Fig.+ . Protein solubility proﬁle of sorghum ﬂour treaded with guar gum and gum Arabic.

Arabic, and combination of+-2ῌῌ (w/w) guar gum and Table+ . The gelation properties of sorghum flour (w/w) gum Arabic did not alter protein solubility at pH treated with guar gum and gum Arabic. +,. At this pH proteins acquire negative charge resulting in dispersion forces keeping the protein in solution. Critical gelation concentration Gelation is an aggre- gation of denatured protein molecules; the least gelation concentration (marked asῌ in Table+ ) of sorghum treated only with guar gum had a least gelation concentration of +0, +2 , and -*ῌ , while the addition of gum Arabic with or without guar gum led the flour to form gel slightly (Table +). Large amount of gum Arabic prevented the gelling of sorghum flour. The least gelation concentration reported for legumes flour was+.ῌ (w/w) for lupin seed proteins (Satheet al., +32, ). Gelation is important in the confection- ary products. Bulk density Sorghum flour with*/ .ῌ (w/w) guar gum has a higher bulk density compared to other treat- ῍῎, not gelled; , gelled slightly; ῌ gelled. ments (Table, ). Increasing the concentration of guar gum to+-2ῌῌ (w/w) or addition of (w/w) gum Arabic leads to a decrease in bulk density but the decrease was sification by flour varies with the type, concentration and not significant (Table, ). Higher bulk density is desirable solubility of the proteins (Achinewhu,+32- ). The addition since it helps to reduce the paste thickness. This is an of+*/ῌῌ (w/w) guar gum and gum Arabic alone or with . important factor in convalescent and child feeding. (w/w) guar gum had higher emulsion activity and stabil- Water and oil binding capacity The addition of guar ity while the addition of*/ .ῌῌ (w/w) guar gum and + gum increased water and oil binding capacities but addi- (w/w) guar gum with-2ῌ (w/w) gum Arabic had lower tion of gum Arabic with or without guar gum decreased emulsion activity (Table, ). Emulsion activity of treated water and oil binding capacities (Table, ). Sorghum flour samples is lower than that of sorghum reported by alone has a higher water and oil binding capacities. . 03 Elkhalifaet al. ( ,**. ), indicating the negative e # ect of and- . .- g/ , g, respectively (Elkhalifaet al., ,**. ). Water gums in this functional behaviour. and oil binding capacity influence food texture (softnessMixing characteristics In the Farinograph mixing or brittleness) of bakery products. characteristics the addition of guar gum alone increased Foaming capacity Sorghum flour showed no foam- water absorption, dough development time and dough ing capacity (Okaka and Potter,+313 ). The addition of stability but the addition of gum Arabic with or without */.ῌ (w/w) guar gum showed a foaming capacity with guar gum decreased water absorption, dough develop- sorghum flour and it increases with increasing the guar ment time and dough stability (Table- ). The mixing gum concentration (Table,-2 ). Also the addition ofῌ characteristics are important for the bakery industry in (w/w) gum Arabic with or without guar gum increased the prediction of the mixing (kneading) performance of the foaming capacity of sorghum flour (Table, ). It is the flour dough. possible that foaming could be due to the added gums.Sensory evaluation of flat bread The score for appear- Emulsion activity and stability The e$ ciency of emul- ance in the presence of-2ῌ (w/w) gum Arabic and com- 330 A. E. O. ELKHALIFA et al.

Table, . Selected functional properties of sorghum ﬂour treated with gum Arabic and guar gum.

Values are meansῌ standard deviation (SD). Means not sharing a common superscript letter in a column are signiﬁcantly di# erent at p῍**/. as assessed by Duncan multiple range test.

Table- .Farinograph mixing characteristics of wheat Table. . Sensory evaluation of flat bread. flour (control) and sorghum flour treated with guar gum and gum Arabic.

Values are meansῌ῍ SE (n +* ). The value in parentheses means total score. A:-2ῌ (w/w) gum Arabic. B:*/ .ῌῌ (w/w) guar gum and -2 (w/w) gum Arabic. C:+-2ῌῌ (w/w) guar gum and (w/w) gum Arabic. D: wheat control.

Table/ . Sensory evaluation of pizza.

bined addition of+-2ῌῌ (w/w) guar gum and (w/w) gum Arabic was close to control (wheat). Similarly, the colour of-2ῌ (w/w) gum Arabic treated sample has a colour comparable to control. Taste of sample treated with combined addition of+-2ῌῌ (w/w) guar gum and Values are meansῌ῍ SE (n +* ). (w/w) gum Arabic is comparable to control. Food texture The value in parentheses means total score. seems to be a factor most a# ected between treated A:+-2ῌῌ (w/w) guar gum and (w/w) gum Arabic. samples and control. Overall acceptability for samples B:*/ .ῌῌ (w/w) guar gum and -2 (w/w) gum Arabic. treated with-2ῌ (w/w) gum Arabic and combined addi- C: wheat control. tion of+-2ῌῌ (w/w) guar gum and (w/w) gum Arabic was of superior acceptability (Table. ). Conclusion Sensory evaluation of pizza Pizza appearance was It was found that the addition of guar gum and gum better for samples treated with combined addition of+#ῌ Arabic in di erent concentrations improved the function- (w/w) guar gum and-2ῌ (w/w) gum Arabic, while colour al properties of sorghum flour. The utilization of guar was of better quality in samples treated with combined gum and gum Arabic as bread improvers promotes the addition of*/ .ῌῌ (w/w) guar gum and -2 (w/w) gum acceptability of bakery products made from sorghum Arabic. This is also applicable for food texture, flavour flour. These products can be used for people su# ering and over all acceptability (Table/ ). from Celiac disease, renal failure and diabetes. Gums as Improvers for Bakery Products from Sorghum 331

References -0-ῌ -1*. AACC International (,*** ). Approved Method of the American LSBU (,**/ ). Guar gum. LSBU, London South Bank University Association of Cereal Chemists,+*th Ed., Methods /.ῌ ,+ .The website, http: //www.lsbu.ac.uk/water/hygua.html Association: St. Paul, MN. Narayana, K. and Narsinga Rao, M.S. (+32, ). Functional pro- Achinewhu, S.C. (+32- ). Protein and food potential of African oil perties of raw and heat processed winged bean (Psophocarpus bean (Pentaclethra macrophylla ) and velvet bean ( Mucunauries ). tetragonolobus) flour. J. Food Sci. .1 ,.3+ῌ .3, . J. Food Sci., .1,.+1-0ῌ +1., Okaka, J.C. and Potter, N.N. (+313 ). Physico-chemical and func- Akubor, P.I. and Chukwu, J.K. (+333 ). Proximate compositions tional properties of cowpea flours.J. Food Sci., .1 ,/-.ῌ /-2 . and selected functional properties of fermented and un- Sabah Elkhier, M.K. (+333 ). Improvement of yield and quality of fermented African oil bean (Pentaclethra macrophylla ) seed guar, PhD Thesis, Faculty of Agriculture, University of flour.Plant Food Hum. Nutr., /. ,,,1ῌ ,-2 . Khartoum, Sudan. Bardford, M.M. (+310 ). A rapid and sensitive method for the Sathe, S.K., Salunke, D.K. and Deshande, S.S. (+32, ). Functional quantification of microgram quantities of protein utilizing the properties of lupin seeds protein and protein concentrate. J. principle of protein - dye binding.Anal. Biochem., 1, ,,.2ῌ ,/. . Food Sci., .1,..3+ῌ .3, Co# man, G.W. and Garcia, V.V. ( +311 ). Functional properties and Sndecor, G.W. and Cochraon, W.G. (+321 ). In statistical methods, 1 amino acid content of a protein isolate from mung -bean flour. th Ed., Ames, IA. The lowa State University Press. J. Food Technol., +,,..1-ῌ .2. The Gum Arabic Company Limited (,**/ ). Applications of Gum Duncan, B.O. (+3// ). Multiple ranges and multipleF test. Bio- Arabic. The Gum Arabic Company Limited Publications, metric, ++,.+.,ῌ Khartoum. Sudan. Elkhalifa, A.O., Sci% er, B. and Bernhardt, R. ( ,**. ). E # ect of Wang, J.C. and Kinsella, J.E. (+310 ). Functional properties of fermentation on the functional properties of sorghum flour. novel proteins: Alfalfa leaf protein.J. Food Sci., .+ ,,20ῌ ,3, . Food Chem., 3,,.+/ῌ Wassermann, L. (,*** ). Bread improvers-action and applications. Kinsella, J.E. (+313 ). Functional properties of Soya proteins. J. Back Mitel Institute, Bonn, Germany. Am. Oil Chem. Soc., /0,.,/.ῌ ,0, Yasumatus, K., Sawada, K., Moritaka, S., Misaki, M., Tado, J. and Lin, M.J.Y., Humbert, E.S. and Sosulski, F. (+31. ). Certain func- Woda, T. (+31, ). Whipping and emulsifying properties of sor- tional properties of sunflower meal products.J. Food Sci., -3 , ghum products. J. Agric. Biol. Chem., -0 ,1+3ῌ 1,/ .