Physicochecaland Microbial Flora Changes Of Steemed Stuffed Bun In Different Storage Conditions

Steamed stuffed bun is a traditional Chinese food which has a long history of thousands of years. This paper studied the properties changes of the steemed stuffed bun under roomtemperture and freezing temperature storage condition, mainly studied the physical and chemical properties and flavor substances and microbialflora constitute of the steamed stuffed bun.The first part of the study is the physical and chemical properties of the steamed stuffed bun, the microstructures of the dough buns were observed by scanning electron microscopy (SEM). The pores of the gluten structure and the degree of exposure of the starch granules increased with the storage time prolonged. The boundaries between the starch granules became obvious and the gluten skeleton was decomposed and the degree of steamed stuffed bun is more serious than that of frozen steamed stuffed bun. The properties of starch during storage were studied by Fourier transform infrared spectroscopy, rapid viscosity analyzer, differential scanning calorimeter and thermogravimetric analyzer. The results showed that with the prolongation of storage time, the starch regrowth of steamed buns at room temperature was higher than that of frozen buns.In the second part, the changes of flavor substances during the storage were studied by headspace solid-phase microextraction and gas chromatography-mass spectrometry(GC-MS). The results showed that, compared with the frozen buns at room temperature, the contents of volatile flavor substances of the two buns were the same, but the difference was not significant, and the flavor of the two buns was basically the same from the point of view of volatile flavor substances. With the extension of storage time, the content of all the substances in the overall difference is not large, some substances have not been detected,and the temperature of steamed stuffed buns to reduce the type of volatile than frozen more,but the overall change is small, indicating that during storage of two buns, the volatile flavor substance basically did not change.In the third part, the composition and change of microbial flora of two kinds of steamed stuffed buns during storage were studied. The results showed that the species diversity of bacteria was different in different storage conditions, and the specific bacterial community structure was formed. The diversity of flora in normal temperature group was higher than that in frozen group. With the time extending, the microbial flora is changing,and the richness of the steamed stuffed bun in the room temperature storage is increasing,the richness of the bacteria in the frozen storage is increased first and then decreased.Analysis of the specific buns have what micro-organisms,and then according to each kind of bacteria to take special control measures.