EFFECT OF SURFACTANT GEL AND GUM COMBINATIONS ON DOUGH RHEOLOGICAL CHARACTERISTICS AND QUALITY OF BREAD

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1 Blackwell Science, LtdOxford, UKJFQJournal of Food Quality Copyright 2004 by Food & Nutrition Press, Inc., Trumbull, Connecticut Original ArticleEFFECT OF SURFACTANT GEL AND GUM ON BREADM.H. AZIZI and G.V. RAO EFFECT OF SURFACTANT GEL AND GUM COMBINATIONS ON DOUGH RHEOLOGICAL CHARACTERISTICS AND QUALITY OF BREAD M.H. AZIZI 1,3 and G.V. RAO 2 1 Department of Food Science & Technology College of Agriculture Tarbiat Modarres University Tehran, Iran 2 Flour Milling Baking & Confectionery Technology Department Central Food Technological Research Institute Mysore, India Accepted for Publication July 3, 2003 ABSTRACT Sodium stearoyl-2-lactylate (SSL), diacetyl tartaric acid esters of monoglyceride (DATEM), glycerol monostearate (GMS) and distilled glycerol monostearate (DGMS) surfactant gels were made with water. Addition of surfactant gels decreased water absorption by the bread while xanthan, karaya, guar and locust bean gums increased the same. Only DGMS or GMS and gum combinations further improved water absorption. All the gums except for guar along with surfactant gels improved dough stability. Both surfactant gels and gums improved the extensograph dough properties of wheat flour to varying degrees. Alveograph characteristics of wheat flour improved to varying extents with surfactant gels while the gums influenced the viscoelastic properties in differing ways. Different combinations of surfactant gels and gums showed varied influences on rapid visco analyzer characteristics of wheat flour. Both surfactant gels and gums improved the bread making quality. Among surfactants, SSL in combination with gums, and among gums locust bean in combination with surfactant gels improved the bread making quality of wheat flour to a maximum extent. INTRODUCTION Bakery products are the most important engineered foods consumed by a large population. White pan bread is predominant among all bakery 3 Contact author. TEL: / ; FAX: ; AZIZIT_M@modares.ac.ir or m.h.azizi@lycos.com Journal of Food Quality 27 (2004) All Rights Reserved. Copyright 2004, Blackwell Publishing 320

2 EFFECT OF SURFACTANT GEL AND GUM ON BREAD 321 products. The quality of bread depends on the quality of wheat flour. The quality of wheat received at the mills varies widely. Hence, the quality of wheat flour supplied to bakeries also varies widely. In order to overcome the problems faced by inconsistent and nonuniform quality of wheat flour, almost all bakeries use various additives to improve dough characteristics and quality of bread. Among functional food additives, surfactants have been increasingly used to improve dough properties and the quality of bread including greater dough strength, improved rate of hydration, greater tolerance to mixing, improved crumb strength, improved slicing characteristics, reduction of shortening needed, increased loaf volume and longer shelf life are among the properties affected. The improvement in bread quality and rheological characteristics of dough with surfactants was reported by Xu et al. (1992). The application of gums to dough has been reported to give increased yields as well as give the dough a greater resilience and a drier, less flabby appearance. The final baked products were also said to have a better softness as well as maintaining a longer shelf life. A well mixed dough containing guar has excellent filming properties. Rolls and bread augmented with guar had a soft texture and improved shelf life (Cawley 1984). Rao et al. (1985) studied the rheological as well as bread making qualities of wheat flour fortified with guar gum and reported improvement in dough properties as well as the quality of the bread. Ellis and Apling (1982) studied the effect of different concentration rates of guar gum on dough and bread and reported marked differences between guar bread and the corresponding control. Neukom and Deuel (1958) investigated the effect of periodic acid-oxidized locust bean gum on the dough and baking characteristics of wheat flour. They found improvement in dough rheological characteristics and larger volumes for the loaves containing gum than the control. Andt (1966) reported that karaya, in combination with carrageenan gum, were effective in retarding staling of bread. He also reported the effect of a blend of gums (karaya, guar, seakem and carrageenan) on dough properties and reported improvement in dough rheology as compared with a control. Christianson (1976) studied the effect of xanthan on rheological properties of wheat flour and reported good loaf volumes and excellent oven spring and improvement in texture for gum-fortified wheat flour compared with control. Rao et al. (1992) studied the effect of incorporation of xanthan gum on the rheological and bread making qualities of wheat flour. The texture and the yield of bread was improved by the incorporation of xanthan gum. Mettler and Seibel (1993) and Mettler et al. (1991) reported improvement in dough rheological characteristics, an increase in specific volume, reduction in crumb elasticity and an increase in crumb firmness during storage with a mixture of surfactants and gums. Brummer et al. (1996) reported improvement in dough properties and bread quality was affected by a combination of surfactants and gums.

3 322 M.H. AZIZI and G.V. RAO As very little work has been carried out on the effect of combination of surfactant gels and gums on dough characteristics and quality of bread, the present work was undertaken to study the effect of surfactant gel and gum combinations on the rheological characteristics of wheat flour dough and the influence of surfactant gel and gum combination on the texture and quality of bread. MATERIALS AND METHODS Materials Glycerol monostearate (GMS) was obtained from M/s Fine Organic Industries, 15/2, Neelkanth Market, M.G. Road, Ghatkopar (East), Mumbai- 400,077, India. Distilled glycerol monostearate (DGMS), sodium stearoyl-2- alactylate (SSL) and diacetyl tartaric acid esters of monoglyceride (DATEM) were obtained from M/s Enzyme India Pvt. Ltd, no. 7 Briethpet Road, Vepery, Chennai-600,007, India. Xanthan gum, guar gum and locust bean gums were obtained from Sigma Chemical Co. St Louis, MO; Karaya gum was procured from the local market. A commercial aestivum wheat flour procured from the local market was used for the studies. Shortening (Hindustan Lever Ltd, 165/ 166, Backbay reclamation, Mumbi 400,020) was procured from the local market. All other chemicals, reagents and solvents used in the present study were of analytical grade and these were obtained from reputed companies. Distilled water (twice distilled) was used in all the experiments throughout the study. Methods Chemical Characteristics. Moisture, total ash, wet and dry gluten, Hagberg falling number, Zeleny sedimentation test, damaged starch and Kent Jones color grade values were determined according to the Standard Procedures of the AACC (1990). Nitrogen content was determined by the micro- Kjeldahl procedure. A conversion factor of 5.7 was used to calculate the protein content. Preparation of Surfactant Gels. Gels were prepared using the surfactants SSL, DGMS, GMS and DATEM and water in the ratio of 0.5 : 2. First dispersions were made and then the dispersions under continuous agitation were heated to a temperature of 65C for GMS, 60C for DGMS, 45C for SSL and 48C for DATEM, respectively. Upon cooling gels were obtained.

4 EFFECT OF SURFACTANT GEL AND GUM ON BREAD 323 Rheological Characteristics Rapid Visco Analyzer (RVA) Characteristics. The pasting characteristics of wheat flour were determined using a Newport Scientific RVA. The system consisted of an external computer linked to a Newport Scientific Analyzer (Model RVA-3D, Sydney, Australia) fitted with a cooling water supply. A software program Thermocline controlled the functions of RVA by signals from the computer, the standard set up profile used for the study. This profile heated the sample at 5C/min from 50 to 95C. After holding for 5 min, it was cooled at 6C/min to 50C and then held for 1 min. The profile was complete in 22 min. The RVA studies were carried out using 2.5 g of flour added to 25 ml water in an aluminum can. Farinograph, extensograph and Chopin alveograph characteristics of wheat flour were determined using the standard AACC (1990) procedure. Effect of Additives on Rheological Characteristics of Wheat Flour. Studies were carried out separately on the effect of SSL, DGMS, GMS and DATEM surfactant gels. Xanthan, guar, karaya and locust bean gums as well as combinations of surfactant gels and gums at the level of 0.5% flour basis alone or in combination were used to evaluate the rheological characteristics of wheat flour as examined by farinograph, extensograph, RVA and alveograph means. Bread Making and Evaluation of Breads. Breads were prepared with wheat flour as well as wheat flour and surfactant gels, gums and combination of surfactant gels and gums. Breads were cooled, packed in polypropylene bags and evaluated after 24 h by a panel of six experienced judges. In this evaluation by consideration of quality characteristics, the overall quality of the breads was evaluated and the results reported as a score. The score was from 100 to 250 with 250 being the highest value. The volume of bread was measured by a rapeseed displacement method (Azizi 2001). The levels of surfactant and gum added were 0.5% each on flour basis either alone or in combination. Measurement of Crumb Firmness (Texture). The crumb firmness in terms of force (g) required for 25% compression of a bread slice 25 mm thick was measured using an Instron instrument (model-1140 Instron Ltd, London, UK). An aluminum plunger having 36 mm diameter was used and the crosshead and chart speed was adjusted to 100 and 200 mm/s, respectively (AACC 1990).

5 324 M.H. AZIZI and G.V. RAO Measurement of Crumb Color. The crumb color of bread in terms of color difference value (DE) was measured using a UV-visible recording spectrophotometer (model UV-2100, Shimadzu Corporation, Tokyo, Japan). A standard white board made from barium sulfate (100% whiteness) was used as a perfectly white object for setting the instrument with illuminant G. Bread slice having 12 mm thickness was placed in the sample holder and the reflectance was auto-recorded for wavelengths ranging from 360 to 800 nm. The DE for sliced bread in comparison with the standard barium sulfate board was spectrophotometrically recorded. Statistical Analysis of Data. All the values reported are average of quadruplicates. The statistical analysis of data was carried out according to a completely randomized design using Duncan s multiple range test to separate the means (Steel and Torrie 1980). RESULTS AND DISCUSSION Chemical Characteristics of Wheat Flour The flour had an ash content of 0.54% and K.J. color grade value of 2.8. The wet gluten content was 37.6% and dry gluten 12.6%. The protein content was 11.5% and the sedimentation value of 24.5 indicated that the flour was medium strong in character. The damaged starch content was 11.8 and falling number was 454. The flour satisfied the requirements of bread flour laid down by Bureau of Indian Standards (IS ) except for an ash content standard of 0.5% on a dry basis. Dough Rheological Properties Farinograph Characteristics. Surfactant gels decreased the water absorption of flour to the extent of %. Addition of different gums increased the water absorption of wheat flour by %. Data on the effect of xanthan gum in combination with SSL, DGMS, GMS and DATEM gels indicated that they increased the water absorption of wheat flour by %. In combination with the same gels, karaya led to water absorption of %. Locust bean and surfact gels increased water absorption by % (Fig. 1). Additional effects, mostly minor ones but a few major ones, may be observed in Fig. 1. The same system will be utilized for subsequent results presented. The reader will be referred to the corresponding table or figure, for brevity s sake, to observe for himself/herself the results gathered when other types of analysis were applied.

6 EFFECT OF SURFACTANT GEL AND GUM ON BREAD 325 FIG. 1. EFFECT OF SURFACTANT GEL AND GUM COMBINATION ON FARINOGRAPH WATER ABSORPTION OF WHEAT FLOUR Rao et al. (1985), Rao et al. (1992) and Andt (1966) reported increases in water absorption by wheat flour with various gums. The dough development time decreased by 0.5 min with SSL and DATEM gels but remained the same for other gels. A decrease in dough development time with guar gum was reported by Rao et al. (1985). The dough stability was increased by min for some surfactant gels. Xanthan gum increased the dough stability very much by 11.0 min, otherwise it increased by min or was unaffected by other gums. There was a considerable increase by min in dough stability with xanthan and different surfactant gels. Rao et al. (1985) reported a decrease in dough stability with the addition of guar gum to wheat flour. Dough stability increased by 0.5 and 1.0 min with DGMS and SSL gels in combination with locust bean. Mixing tolerance index either at 10 min or at 20 min was reduced by a maximum 10 BU in some cases or otherwise remained the same for the surfactant gels (Fig. 2). The mixing tolerance index was affected to a maximum of 10 BU with different gums, but for xanthan gum it was reduced by 60 BU. The mixing tolerance index decreased from 60 to 30 BU at 10 min and from 100 to 60 BU at 20 min with xanthan and different surfactant gels. There was an increase in the mixing tolerance index by BU at 20 min with locust bean and different surfactant gels except for DGMS gels.

7 326 M.H. AZIZI and G.V. RAO FIG. 2. EFFECT OF SURFACTANT GEL AND GUM COMBINATION ON EXTENSOGRAPH RESISTANCE TO EXTENTION OF WHEAT FLOUR The valorimeter value increased by 2 and 4 for DGMS and SSL gels, respectively. The valorimeter value was increased by 18 for xanthan gum and by 2 for other gums. Only SSL with guar gum improved the valorimeter value by 4 and all other gels reduced it by 2. Andt (1966) reported improvement in valorimeter value, hence increase in dough strength with different gums. Extensograph Characteristics. An increase in resistance to extension by BU was revealed when SSL, DGMS, GMS and DATEM gels were added to wheat flour. Addition of different gums to wheat flour increased the resistance to extension by BU. Xanthan gum and surfactant gels increased the resistance to extension by BU, karaya gum in combination with surfactant gels increased resistance by BU, combinations of guar gum and surfactant gels increased resistance by BU, locust bean gum and surfactant gels increased resistance by BU (Fig. 2). Rao et al. (1992) reported an increase in resistance to extension by addition of xanthan gum to wheat flour. Extensibility decreased by mm with the addition of surfactant gels. Xanthan gum and surfactant gel combinations decreased extensibility by 36 mm, karaya gum in combination with surfactant gels by mm and guar gum and surfactant gels by mm. The combination of locust bean gum and surfactant gel increased the extensibility by mm.

8 EFFECT OF SURFACTANT GEL AND GUM ON BREAD 327 Rao et al. (1992) reported a decrease in extensibility with addition of xanthan gum to wheat flour. The ratio figures varied from 2.8 to 4.6 with addition of different surfactant gels. The ratio figures were from 2.6 to 3.2 with the addition of different gums. The ratio figures varied from 3.2 to 4.6 with xanthan gum and surfactant gels, from 2.8 to 4.2 with karaya and surfactant gels, from 2.7 to 4.0 with guar and surfactant gels and from 2.7 to 3.6 with locust bean and surfactant gels. GMS, DGMS, SSL and DATEM gels increased the area by 6, 17, 24 and 28 cm 2, respectively. The areas were increased by 2, 7, 8 and 13 cm 2 for locust bean, karaya, guar and xanthan gums, respectively. The increases in areas were 3, 6, 29 and 31 cm 2 for GMS, DGMS, SSL and DATEM gels in combination with xanthan gum, from 1 to 13 cm 2 with karaya and surfactant gels, from 2 to 25 cm 2 with guar and surfactant gels and from 2 to 19 cm 2 with locust bean and surfactant gels. Alveograph Characteristics. A decrease in dough tenacity except for DATEM with addition of surfactant gels (Fig. 3) was detected. The gums increased the tenacity of wheat flour dough, which was opposite to the effects of surfactant gels. Surfactant gels in combination with xanthan gum increased dough tenacity by mm, the combination of karaya gum and surfactant gels by mm, by mm with the addition of guar gum and surfactant gels restore by 7 12 mm. FIG. 3. EFFECT OF SURFACTANT GEL AND GUM COMBINATION ON ALVEOGRAPH DEFORMATION ENERGY OF WHEAT FLOUR

9 328 M.H. AZIZI and G.V. RAO There were increases in extensibility with addition of surfactant gels. The gums decreased the extensibility of wheat flour dough, which was opposite to the effects of surfactant gels. Surfactant gels in combination with xanthan gum decreased the extensibility by mm, karaya gum and surfactant gels decreased extensibility by mm, extensibility decreased by mm with addition of guar gum and surfactant gels and locust bean gum and surfactant gels decreased the extensibility by mm. The swelling index increased by ml and deformation energy by 2 12 with different surfactant gels. Swelling indices decreased by ml; however, the deformation energy increased by 4 37 with different gums. Surfactant gels in combination with xanthan gum reduced the swelling indices by ml and increased the deformation energy by Both swelling index and deformation energy decreased with the combinations of karaya gum and surfactant gels, by while deformation energy increased by 6 for SSL and decreased by 6 10 with the addition of guar gum and surfactant gels. The swelling index was reduced by and deformation energy also decreased by 7 18 with locust bean gum and surfactant gels (Fig. 3). The configuration ratio varied from 1.3 to 1.7 with addition of surfactant gels. Configuration value ranged between 3.5 and 4.5 with addition of gums. The configuration ratios were high and varied between 4.5 and 5.9 with surfactant gels in combination with xanthan gum. The configuration ratios were in the range from 4.5 to 5.4 with the combination of karaya gum and surfactant gels, they ranged from 3.7 to 5.0 with addition of guar gum and surfactant gels and ranged from 4.0 to 4.6 with locust bean gum and surfactant gels. Rapid Visco Analyzer Characteristics. Data showed that the gelatinization temperature varied from 63.7 to 64.3C with the addition of surfactant gels as against 64.4C for control wheat flour (Fig. 4). The gelatinization temperature varied between 63.1 and 64.4C with addition of gums. The peak viscosity was reduced by 1 RVU with SSL gel but reduced by RVU with other gels. The peak viscosity increased by 1 and 3 RVU with locust bean and guar gums, respectively, and decreased by 4 and 5 RVU with xanthan and karaya gums, respectively. GMS and DATEM showed considerable decrease in peak viscosity and hot paste viscosity while SSL and DGMS influenced the same only marginally in combination with xanthan gum. SSL and DGMS affected peak viscosity marginally but GMS and DATEM lowered the same to a considerable extent in combination with karaya gum. Addition of guar gum in combination with surfactant gels increased the peak viscosity by RVU, addition of locust bean gum along with SSL, DGMS, GMS and DATEM gels separately increased the peak viscosity by 4

10 EFFECT OF SURFACTANT GEL AND GUM ON BREAD 329 FIG. 4. EFFECT OF SURFACTANT GEL AND GUM COMBINATION ON RVA PEAK VISCOSITY OF WHEAT FLOUR 13 RVU (Fig. 4). Bahnassey and Breene (1994) studied the effect of different levels of various gums on starch cooking properties and reported increase in peak viscosity at high gum concentration especially with locust bean gum for various starches. Hot paste viscosity was decreased marginally by 1 3 RUV for SSL and DGMS, respectively, and by 9 and 19 for GMS and DATEM. The cold paste viscosity increased considerably by 54, 70 and 27 RVU for SSL, DGMS and GMS, respectively. However, the cold paste viscosity was increased by only 3 RVU for DATEM. The hot paste viscosity decreased by 7 11 RVU while the cold paste viscosity showed increases by 0 4 RVU. SSL and DGMS affected hot paste viscosity marginally but GMS and DATEM lowered the same to considerable extents. The cold paste viscosity increased to varying extents with karaya gum and surfactant gel combinations. Addition of guar gum in combination with surfactant gels increased the hot paste viscosity by 4 9 RVU. Wide variations in the increase in cold paste viscosity by RVU were noticed with addition of guar gum and surfactant gel combination. Addition of locust bean gum along with SSL, DGMS, GMS and DATEM gels separately increased the hot paste viscosity by 1 20 RVU and cold paste viscosity by RVU. Use of an RVA to measure the effects of sucrose ester emulsifiers and sugar emulsifier interactions on starch pasting properties has been reported by Deffenbaugh et al. (1990). Ravi et al. (1999) showed

11 330 M.H. AZIZI and G.V. RAO that GMS, SSL and DATEM surfactants altered the pasting properties of both weak and medium strong flours. Effect of Surfactant Gels and Gum Combinations on Loaf Volume of Bread Data on the effect of combination of gums and surfactant gels on loaf volume of bread are presented in Table 1. SSL, DGMS, GMS and DATEM gels and xanthan, karaya, guar and locust bean gums when added separately improved loaf volume of bread to varying extents. Surfactant gels and SSL improved loaf volume to a maximum extent, followed by DGMS, GMS and DATEM while locust bean gum improved loaf volume to a maximum extent, followed by guar, karaya and xanthan gums. The extent of improvement with surfactant gels was between 40 and 75 ml while with gums it was between 5 and 40 ml. When xanthan was added along with surfactant gels, the volume of bread reduced in comparison with that of the volume with respective surfactant gel. However, the volume of bread improved over that of the volume obtained with gel alone with the addition of all other gums. Maximum improvement in loaf volume of bread was observed with locust bean gum and surfactant combinations, followed by guar and karaya gum combinations with surfactants (Table 1). Christianson (1976) reported the use of xanthan gum along with gluten for improving bread volume. The improvement in loaf volume was only 5 ml when xanthan gum was added. Rao et al. (1992) also reported no change in loaf volume with addition of xanthan gum. TABLE 1. EFFECT OF COMBINATION OF SURFACTANT GELS* AND GUMS ON LOAF VOLUME OF BREAD Treatment Loaf volume (ml) Control SSL DGMS GMS DATEM SEM (+) Control 505a 580d 570c 545b 550b 3.93 Xanthan 510a 555d 550cd 535b 540bc 2.93 Karaya 525a 585d 580d 545b 555c 2.99 Guar 535a 595c 590c 560b 565b 3.08 Locust bean 545a 610d 605d 575b 590c 3.19 SSL, Sodium stearoyl-2-lactylate; DGMS, Distilled glycerol monostearate; GMS, Glycerol monostearate; DATEM, Diacetyl tartaric acid esters of monoglyceride. All the values reported are average of quadruplicates. * Prepared using surfactant and water in the ratio of 0.5 : 2.0 Added at 0.5% level on flour basis. Values in the same row followed by a different letter differ significantly. Standard error of mean at 17 degrees of freedom.

12 EFFECT OF SURFACTANT GEL AND GUM ON BREAD 331 TABLE 2. EFFECT OF COMBINATION OF SURFACTANT GELS* AND GUMS ON SPECIFIC VOLUME OF BREAD Treatment Specific volume (ml/g) Control SSL DGMS GMS DATEM SEM (±) Control 3.74a 4.26d 4.22d 4.00b 4.07c 0.03 Xanthan 3.74a 4.11d 4.04c 3.96b 3.97b 0.07 Karaya 3.89a 4.30c 4.26c 4.04b 4.08b 0.04 Guar 3.93a 4.41e 4.34d 4.12b 4.18c 0.05 Locust bean 4.04a 4.48d 4.48d 4.23b 4.37c 0.06 SSL, Sodium stearoyl-2-lactylate; DGMS, Distilled glycerol monostearate; GMS, Glycerol monostearate; DATEM, Diacetyl tartaric acid esters of monoglyceride. All the values reported are average of quadruplicates. * Prepared using surfactant and water in the ratio of 0.5 : 2. Added at 0.5% level on flour basis. Values in the same row followed by a different letter differ significantly. Standard error of mean at 17 degrees of freedom. Effect of Surfactant Gels and Gum Combinations on Specific Volume of Bread Data on the effects of combinations of gums and surfactant gels on the specific volume of bread are presented in Table 2. Specific volume of bread improved with surfactant gels and gums when added separately. Only xanthan gum did not show an improvement. As such, xanthan addition reduced the specific loaf volume of breads obtained with surfactant gels. All other gums improved the specific loaf volume of breads obtained with surfactant gels. Maximum improvement in specific volume was obtained with locust bean gum and surfactant gels combinations, followed by guar and karaya gum with surfactant gel combinations. Mettler and Seibel (1993) reported an increase in specific volume of whole bread with the addition of guar gum, GMS and DATEM. Effect of Surfactant Gels and Gum Combinations on Texture of Bread The effect of combination of gums and surfactant gels on texture of bread is presented in Table 3. The texture of bread improved as shown by a reduction in compression force with surfactant gels and gums separately. The improvement in texture was better with surfactant gels ( g forces) as compared with gums ( g forces). Addition of xanthan reduced the improvement to texture of bread with the use of surfactant gels. All other gums improved the texture of bread to the level of improvement brought out by surfactant gels

13 332 M.H. AZIZI and G.V. RAO TABLE 3. EFFECT OF COMBINATION OF SURFACTANT GELS* AND GUMS ON TEXTURE OF BREAD Treatment Texture (g. force) Control SSL DGMS GMS DATEM SEM (+) Control 413d 323a 326a 345c 335b 2.46 Xanthan 381d 332a 340b 350c 348c 3.40 Karaya 354d 316a 319a 343c 332b 2.34 Guar 350d 281a 312b 329c 327c 4.08 Locust bean 345e 259a 270b 325d 312c 3.17 SSL, Sodium stearoyl-2-lactylate; DGMS, Distilled glycerol monostearate; GMS, Glycerol monostearate; DATEM, Diacetyl tartaric acid esters of monoglyceride. All the values reported are average of quadruplicates. * Prepared using surfactant and water in the ratio of 0.5 : 2.0. Added at 0.5% level on flour basis. Values in the same row followed by a different letter differ significantly. Standard error of mean at 17 degrees of freedom. alone. Locust bean gum showed maximum improvement followed by guar and karaya gums when added in combination with surfactant gels (Table 3). SSL with all gums showed the highest improvement in texture among the surfactant gels. Cawley (1984) and Rao et al. (1985) reported improvement in texture of bread with the use of guar gum. Andt (1966) showed improvement in texture of bread with use of karya gum. Rao et al. (1992) showed that xanthan gum improved the texture of bread. Mettler and Seibel (1993) reported improvement in whole-wheat flour bread crumb characteristics with a mixture of GMS, DATEM and guar gum. Effect of Surfactant Gels and Gum Combinations on Quality of Bread Crumb value improved with the addition of surfactant gels better than with gums. SSL and DGMS increased crumb value better than GMS and DATEM in combination with gums. Baking quality scores of bread increased with surfactant gels and gums. SSL in combination with gums increased baking quality scores better than the gel and gum combinations. Similarly, locust bean gum in combination with gels increased baking quality score better than other gum and gel combinations. The overall quality score of bread improved better with surfactant gels than with gums (Table 4). The quality score varied from 184 to 235 for gels and for gums. Xanthan reduced the overall quality score obtained with respective surfactant gels. All other gums improved the overall quality scores obtained with surfactant gels. The overall quality scores ranged from 217 to 250 with

14 EFFECT OF SURFACTANT GEL AND GUM ON BREAD 333 TABLE 4. EFFECT OF COMBINATION OF SURFACTANT GELS* AND GUMS ON OVERALL QUALITY OF BREAD Treatment Overall quality score Control SSL DGMS GMS DATEM SEM (±) Control 122a 235d 215c 184b 186b 2.99 Xanthan 131a 208d 186c 155b 182c 2.25 Karaya 151a 237d 235d 184b 208c 2.04 Guar 155a 242c 240c 210b 213b 2.00 Locust bean 184a 250d 247d 217b 240c 2.85 SSL, Sodium stearoyl-2-lactylate; DGMS, Distilled glycerol monostearate; GMS, Glycerol monostearate; DATEM, Diacetyl tartaric acid esters of monoglyceride. Breads were evaluated after 24 h by a team of six expert panelists. The scores was from 100 to 250 with 250 being the highest value. All the values reported are average of quadruplicates. * Prepared using surfactant and water in the ratio of 0.5 : 2.0. Added at 0.5% level on flour basis. Values in the same row followed by a different letter differ significantly. Standard error of mean at 17 degrees of freedom. locust bean and gel combinations, followed by scores of with guar and gel combinations and by with karaya and gel combinations. The overall quality scores ranged from 205 to 250 with SSL, with DGMS, with DATEM and with GMS when added in combination with gums. Brummer et al. (1996) reported improvement in whole-wheat flour bread quality with a mixture of GMS, DATEM and guar gum. Effect of Surfactant Gels and Gum Combinations on Crumb Color of Bread The color of crumb improved with addition of surfactant gels but it was not affected much with addition of gums (Table 5). Marginal changes in color were noticed when gums and gels were used in combination. Only locust bean gum in combination with surfactant gels showed noticeable improvement in the color of breads. In all, both surfactant gels and gums improved the bread making quality when added separately. Xanthan gum reduced improvement in the effect of surfactant gels. All other gums further improved the bread making quality obtained by gels alone. Among surfactants, SSL in combination with gums and among gums locust bean in combination with gels improved the bread making quality of wheat flour to a maximum extent.

15 334 M.H. AZIZI and G.V. RAO TABLE 5. EFFECT OF COMBINATION OF SURFACTANT GELS* AND GUMS ON CRUMB COLOR (DE) OF BREAD Treatment Crumb color (DE) Control SSL DGMS GMS DATEM SEM (±) Control 33.8d 28.8a 29.4a 31.8c 31.1b 0.23 Xanthan 33.5d 31.0a 31.2a 32.9c 32.3b 0.20 Karaya 33.1d 28.5a 28.7a 31.8c 29.9b 0.01 Guar 32.7c 28.1a 28.3a 29.7b 29.6b 0.18 Locust bean 32.1d 27.5a 27.6a 29.2c 28.2b 0.16 SSL, Sodium stearoyl-2-lactylate; DGMS, Distilled glycerol monostearate; GMS, Glycerol monostearate; DATEM, Diacetyl tartaric acid esters of monoglyceride. All the values reported are average of quadruplicates. * Prepared using surfactant and water in the ratio of 0.5 : 2.0. Added at 0.5% level on flour basis. Values in the same row followed by a different letter differ significantly. Standard error of mean at 17 degrees of freedom. CONCLUSIONS Addition of SSL, DGMS, GMS and DATEM gels decreased water absorption while xanthan, karaya, guar and locust bean gums increased the same. Only DGMS or GMS and gum combinations further improved water absorption. All the gums except for guar along with surfactant gels improved dough stability. Both surfactant gels and gums improved the extensograph dough properties of wheat flour to varying degrees. Generally, the resistance to extension increased and extensibility decreased with all combinations of surfactant gels and gums. Alveograph characteristics of wheat flour improved to varying extents with surfactant gels while the gums influencd the viscoelastic properties in differing ways. All the surfactant gels and gums combinations showed almost similar effect on dough properties, but to varying degrees. Different combination of surfactant gels and gums showed varied influences on RVA characteristics of wheat flour. Both surfactant gels and gums improved the bread making quality, when added separately. Xanthan gum reduced the improvement effect of surfactant gels. All other gums further improved the bread making quality of wheat flour obtained by the surfactant gels alone. Among surfactants, SSL in combination with gums, and among gums locust bean in combination with surfactant gels improved to a maximum extent the bread making quality of wheat flour.

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