|dc.description.abstract||The effect of incorporation of wheat bran, oat bran and buckwheat into Chinese steamed bread on dough rheology and quality were investigated. The additon of bran and buckwheat flour into wheat flour can influence the dough rheology and final quality of Chinese steamed bread due to the high hydration properties of DF and the disruption of the starch-gluten network by DF. For instance, the addition of bran significantly increased water absorption, development time and stickiness, whereas decreased extensibility. In consequence, the specific volume of CSB reduced significantly and hardness, gumminess and chewiness increased significantly as the substitution increased from 0 to 15 %. Additionally, the results also show that the substitution level of bran and buckwheat flour into wheat flour can be increased up to 15 % resulting in a reduced predicted glycaemic response which may confer significant health benefits to the consumer.
In order to overcome the negative effects, three types of commercial enzymes were added into the Chinese steamed bread incorporated with 15 % bran and buckwheat. There were two experimental designs were performed: the first one to evaluate the effect of single enzyme on the dough rheology and breadmaking properties, and the second one to investigate the effect of combined enzymes on the dough rheology and breadmaking properties. The results showed that the dough handling and breadmaking properties were improved slightly, whereas no significant difference in fibre content, starch content and AUC value. In comparison with single enzyme, the enzymes combinations are more effective in the rheological properties of dough and quality of Chinese steamed bread incorporated with 15 % bran and buckwheat flour due to the synergistic effect of α-amylase, xylanase and cellulase. Additionally, the combined enzymes reduced the fibre and starch content, resulting in varied AUC value. The results obtained from full factorial design suggested that the combination of α-amylase, xylanase and cellulase had interactions among enzymes and their coupled reactions.
The combination of α-amylase, xylanase and cellulase revealed a good potential to be used as bread improver in baking industry. However, this research found the optimum concentration of enzymes was associated with higher AUC value than the bran and buckwheat CSB without enzymes. For the baking industry, the consistent pursuit of high quality of product will also bring to the loss of nutritional value. This study is a first step to understand how the bran and enzymes affect the dough rheology and bread quality, thus further research need to be done in the future.||en