Preparation Of Bran Jiaozi And Its Application In Making Chinese Steam Bread

Jiaozi is a traditional leaven in China, and it has a peculiar flavor. The existing commodity Jiaozi are mostly made by rice flour. However, the study of new material is still insufficient, for there were neither uniform conclusions nor significant results. This research focused on both the making process of Jiaozi made of wheat bran and the applying of this new kind of bran Jiaozi in making Chinese steamed bread(CSB). What’s more, the application effect and feasibility of this process was explored specifically.Firstly, we found out the basic making process of bran Jiaozi and conducted a preliminary of this making process. Six factors which had effects on bran Jiaozi’s making process were considered, including particle size of wheat bran, addition amount of wheat bran, addition amount of Daqu, addition volume of water, fermentation temperature and fermentation time. By detecting fermenting power, amylase activity and the number of yeast, tentatively concluded that the following conditions were relatively better, the particle size of wheat bran was the original size, the fermentation temperature was 25℃, the addition amount of wheat bran was 0.1-0.3 times(based on the quality of fermented glutinous rice, similarly hereinafter), the addition amount was 1.5-2.5 percent, the addition volume of water was 0.5-1.5times, the fermentation time was 20-28 h.Secondly, the making process of bran Jiaozi was optimized primarily with orthogonal experiments. By using orthogonal experimental design, fermentation time, bran addition amount, Daqu addition amount, and water addition volume were investigated. Using range and variance analysis with the results of amylase activity, sense scores, hardness and specific volume, the making process were concluded that the fermentation time were 28 h, the fermentation temperature were 25℃, the addition amount of wheat bran was 0.1 times, the addition amount was 2.5%, the addition volume of water was 1.0 times.Thirdly, the pasting properties of flour and the mixing properties of CSB dough, as well as fermentation process pH, titratable acidity, dough volume, gas production and holding capacity were studied, while bran Jiaozi were added. This study showed that the Bran Jiaozi could improve the fermentation performance of dough and decrease the kneading resistance slightly; The bran Jiaozi could accelerate the acidification of dough more quickly than the yeast, and the acid yield of dough was lower than the rice flour Jiaozi; The fermentation power of bran Jiaozi was better than rice flour Jiaozi but did not perform as well as the yeast; Since applying the bran Jiaozi, the dough fermentation time would be significantly increased, while the capability of keeping gas was also at a high level.Finally, the application characteristics of bran Jiaozi to make CSB were studied by using sensory evaluation, texture instrument, GC-MS, etc. The bran particle in Jiaozi could reduce the whiteness of CSB and worsened the taste of bread, and then had an adverse effect in sense scores; By using the two stage fermentation method to make CSB, the bran Jiaozi could increase the specific volume of CSB more significantly than other kinds of leavens; The CSB made by bran Jiaozi could be sticky but soft,and it’s easy to chew; Maturation degree of starch in CSB made by bran Jiaozi was low, but the hardness was lower than the CSB made by rice flour Jiaozi and yeast during 60h’s storage; The CSB made by bran Jiaozi have lower content of esters but have higher content of alcohol, aldehydes, ketone and furan which were helpful to improve the flavor of CSB; The content of phenethyl alcohol was the highest among these three kinds of CSB. Overall, the wheat bran Jiaozi has played a unique effect in making CSB, and had a higher application value.