Effect of Dough Improver on Wheat Bread Quality Abstract Effect of dough improver which consisted of various L-Ascorbic acid: LCysteine ratios on Wheat bread quality were studied. It was found that raising of LAscorbic acid would increase flour water absorption while increasing of L-Cysteine had inverse effect. But L-Cysteine would improve specific bread volume. Optimum ratio of L-Ascorbic acid and L-Cysteine was 60:40 ppm. Bread which added L-Ascorbic acid: L-Cysteine (60:40 ppm. of weight flour) had maximum specific bread volume, 3 3.4297 em Ig., and good over all acceptance. Adding developed dough improver (60:40 . ppm.) improved wheat bread quality but it was not significantly difference from commercial dough improver (U-99). Introduction Dough improvers are often added to flour for improving dough elasticity and baking quality (Stauffer. 1990). For better acting. dough improver often consisted of axidizing and reducing agent. While Reducing agent such as Glutathione. Cysteine and a-Glucosyl Rutin (Morita et ai, .1996).reduced kneading force and dough fermentation time by accelerating of gluten disrupture and then sulfhydryf group were increased (Biebaut,1991). Oxidizing agent such as Ascorbic acid and Azodicarbonamide increased dough strength by oxidized sulfhydryl group to disulfide bond (Bennion. 1995). So, optimum ratio of L-Ascorbic acid and L-Cysteine for improving wheat bread quality were studied and compared with commercial dough improver. Method 1. Effect of L-Ascorbic acid and l-Cysteine on wheat bread quality was studied by adding 100 ppm. of l-Ascorbic acid: l-Cysteine to flour (wfw), in the followingratio; 100:0, 90:10, 80:20, 70:30, 60:40,50:50, 40:60, 30:70, 20:80, 10:90, 0:100. Flour water absorption. specific bread volume and sensory evaluation were measured. Specific bread volume was determined by black sesame displacement. Sensory characteristic was evaluated by 9-point hedonic scale and samples were served in BIB design. 2. Optimum ratio of l-Ascorbic acid: l-Cysteine was chosen and compared with commercial dough improver in such properties as determined in 1. Results and Discussion 1. Effect of L-Ascorbic acid and L-Cysteine on wheat bread quality. It was found that increasing of l-Cysteine would decrease flour water absorptio but L-Ascorbic acid had inverse effect as shown in table 1. Raising of l-Cysteine trended to increase specific bread volume but adding more than 50 ppm. affected inversely. Sensory evaluation showed that adding L-Ascorbic acid up to 60 ppm. increaded volume and over all acceptance scores but increasing more than 60 ppm. decreased those scores (Table 2). It may result from gluten disrupture accelerating of l-Cysteine which induced too much S-H group forming during kneading. caused worse dough characteristic, too soft, sticky and less elasticity. Too soft dough was uilable to retain gas during fermentation so there were many pores on dough surface after fermentation. But L-Ascorbic acid reformed gluten to three dimensional matrix and oxidized S-H group to S-S bond which increased dough: strength in retaining gas, so it enlarged bread volume. However, over adding L-Ascorbic acid (more than 60 ppm) gave inverse effect (less bread volume) which may result from improper ratio. L-Ascorbic acid and L-Cysteine. Moreover, too much strengthened dough was unable to retain gas because of its elasticity lack. Table 2 Sensory evaluation of bread which added various ratios of l-Ascorbicacid and L-Cysteine 2. Comparison of developed and commercial dough Improver. Bread which added developed dough improver (L-Ascorbic acid:L-Cysteine ;60:40) and commercial dough improver (U-99) were compared with control. It was found that dough improver had effect on flour water absorption and bread quality as show in Table 3. U-99 gave maximum flour water absorption and specific bread volume. Table 3 Effect of dough improver on flour water absorption and specific bread volume. Sensory evaluation cht)wed that dough improver increasrd bread preference score such as air cell. volume, tenderness. toughness and over all acceptance score. (Table 4) U-99 had better effect than L-Ascorbic acid: L-Cysteine (60:40 ppm.) but significantly difference in over all acceptance score. It mean that bread quality depend on several characteristic. Table 4 Effect of dough improver on wheat bread sensory evaluation. Conclusion Using of L-Ascorbic acid and L-Cysteine combination as dough improvers, improved bread quality better than adding alone. L-Ascorbic acid increased flour water absorption while L-Cysteine had inverse effect. Optimum ratio of L-Ascorbic acid and L-Cysteine was 60 : 40 ppm. With this ratio, bread had maximum specific volume and had high preference score. Added U-99 bread had maximum specific volume and highest preference score in all characteristic. Bread which- was added L-Ascorbic acid: L-Cysteine (60:40) and control had lower score accordingly. 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