Character Of Liquid Fermentation By JiaoZi And Its Effect On The Quality Of Steamed Bread

Jiaozi was chosen as the original leaven for batter fermentation, started from the Jiaozi batter modulation technology, to select the most suitable conditions of the production technology of Jiaozi batter steamed bread with the filtered Jiaozi batter as an intermediate starter cultures, the effect on the quality of Jiaozi batter steamed bread was discussed. Water distribution inside Jiaozi batter steamed bread dough during fermenting steaming and changes in the quality of steamed bread during storage at 25oC were studies. Compared with Yeast batter steamed bread, Secondary fermentation steamed bread and Ordinary yeast steamed bread. Volatile components, starch digestion in vitro, changes of internal moisture content and distribution, DSC measurement retrogradated were investigated to explore the flavor, taste and aging mechanism of Jiaozi batter steamed bread.(1) In terms of Jiaozi batter modulation technology, single factor experiments showed that when Jiaozi adding amount was 5%~20%, flour-water ratio was 0.3~0.6, fermentation temperature was 22 o C~34 o C, fermentation time was 12h~24h, Jiaozi batter quality was relatively suitable. Orthogonal experiment optimum modulation process of Jiaozi batter:fermentation temperature was 30oC, flour-water ratio was 0.5, Jiaozi adding amount was 20%,fermentation time was 20 h.(2) In terms of Jiaozi batter steamed bread production process, single factor experiments showed that when Jiaozi batter adding amount was 40%~50%, fermentation time was 1.5h~2h,fermentation temperature was 30 o C~38 o C, alkali adding amount was 0.7%~0.8% of the Jiaozi batter, the quality of Jiaozi batter steamed bread was better. Finally Jiaozi batter steamed bread production process was determined by orthogonal experiment as: the amount of Jiaozi batter 40%,the amount of alkali 0.75%, fermentation temperature 35oC, fermentation time 1h45 min.(3) The water distribution characteristics inside Jiaozi batter steamed bread dough during fermenting-steaming are as follows: before the dough fermentation, there were threekinds of water including strongly bound water, weakly bound water and free water; after fermentation, there were a lot of weakly bound water and a very small amount of free water in the dough; after steaming, the steamed bread only contained strongly bound water and weakly bound water. And strongly bound water were kept in a high level.(4) The hardness of Jiaozi batter steamed bread rose sharply during storage at 25oC then slowly rose and remained unchanged finally. The springiness, cohesiveness and resilience initially decreased. After a period of time to reached a suitable value. The chewiness first increased rapidly during storage, then presented a slight increase.(5) Volatile components of Jiaozi batter steamed bread were analyzed by GC-MS.Results showed that the types and total volatiles content of Jiaozi batter steamed bread were more than that of Yeast batter steamed bread and Secondary fermentation steamed bread.However ketenes and ethers could not be detected from Ordinary yeast steamed bread.Unpleasant odor components cannot be mixed with each other, thus the unique flavor of steamed bread was affected.(6) Results of in vitro starch digestion experiments of Jiaozi batter steamed bread showed that the content of RDS and SDS in Jiaozi batter steamed bread were slight higher than other steamed breads. It proved that the starch digestion performance of Jiaozi batter steamed bread was better but not obvious in superiority.(7) By studies on the change in hardness and water distribution(NMR) of Jiaozi batter steamed bread during storage, the rate of aging in Jiaozi batter steamed bread was the lowest during storage, the rate of aging in Ordinary yeast steamed bread was the highest, the rate of aging in Yeast batter steamed bread and Secondary fermentation steamed bread was in the middle of the other steamed breads.(8) According to DSC measurement of starch retrogradation, Jiaozi batter steamed bread presented minimum heat enthalpy released by melting amylopectin crystallization. The degree of starch retrogradation was the lowest of all, followed by Yeast batter steamed bread and Secondary fermentation steamed bread. However, the Ordinary yeast steamed bread showed the most serious starch retrogradation phenomena.In general, fermented Jiaozi batter could achieve the effect or even better than traditional fermented dough, and it was more suitable for industrial production of steam bread.