Studies On Microbial Community Diversity In Sourdough From Different Areas Of China And Its Effect On The Characteristics Of Steamed Bread

As the traditional basic food of the Chinese nation,steamed bread is more suitable for Chinese taste because of its mellow aroma of wheat.In this paper,the traditional starter and steamed bread were used as the main research objects.This paper mainly studied the diversity of microflora in the sourdough,the process optimization of the steamed bread,the effects of fermentation on the quality of the dough and steamed bread and the changes of the dry yeast steamed bread and the sourdough steamed bread in storage period.The purpose of this study is to study and develop traditional starter and traditional pasta,and to lay a foundation for the industrialized production of steamed bread as a traditional staple food.Firstly,the composition of microbial community in sourdough from Xingtai Hebei(HB),Yuncheng Shanxi(SX),Caoxian Shandong(SD)and Lijiang Yunnan(YN)was investigated systematically by high-throughput sequencing technology.And the influence of the flora on steamed bread was studied.The results showed that the number of bacteria of sourdough samples was significantly greater than that of fungi.Basidiomycota has the largest relative abundance in the phylum level of fungi,and Firmicutes had the largest relative abundance in the phylum level of bacteria.In the genus level of bacteria,Pediococcus was the most abundant in HB,SX and SD samples,however,Lactobacillus was the most abundant in YN sample.The rich flora of the sourdough may improve the texture of steamed bread and make the internal structure of steamed bread more delicate and soft.Then,the technological parameters of steamed bread were optimized.Taking the sensory score of steamed bread as the main index,to analyze the addition of the sourdough,the fermentation temperature,the fermentation time of dough and the secondary fermentation time four factors on single factor and orthogonal test.The optimum technological parameters of steamed bread in different areas were determined by orthogonal test.On the basis of these technological parameters,the influences of sourdough fermentation and pure yeast fermentation on dough rheology,specific volume of steamed bread,texture and flavor were compared.The results showed that sourdough fermentation could improve dough rheology,increase the specific volume of steamed bread,improve the texture of steamed bread,make the internal structure of steamed bread more delicate and soft,and endow the steamed bread with rich flavor.The quality of sourdough steamed bread is better than that of dry yeast steamed bread,which may be related to the abundant flora in the sourdough.Finally,through the storage(4?)of steamed bread,it was found that with the increase of storage time,the content of flavor substances in steamed bread was unstable,but there were relatively stable flavor substances.It was found that the hardness and starch gelatinization enthalpy of sourdough steamed bread were lower than that of dry yeast steamed bread,and the binding ability of water was stronger than that of dry yeast steamed bread.Compared with dry yeast steamed bread,sourdough fermentation can delay the aging of steamed bread and is more resistant to storage.