Studies On The Technology Of Traditional Flavor Frozen Steamed Bread Dough

In this paper, in order to study the application of traditional starter culture Jiaozi in frozen dough,firstly, the producing process of yeast and Jiaozi frozen steamed bread dough were optimized by response surface method respectively, and then the influence of yeast mixed with Jiaozi on the quality of frozen steamed bread dough were determined, to find out the most suitable mixing proportion and fermentation time,and the comparision of the advantages and disadvantages of frozen dough steamed bread made by three kinds of starter culture were also conducted. The effect of freezing conditions and thawing methods on the qualities of Jiaozi frozen steamed bread dough were investigated, in order to improve the quality of frozen steamed bread dough, the formulas of composite additives of Jiaozi and mixed fermentation frozen steamed bread dough were optimized based on response surface method; At last, the flavor substances and micro structure of different kinds of frozen dough were studied by GC-MS and scanning electron microscope; The results of the study were as follows:1. The optimum process parameters of yeast frozen steamed bread dough were: the quantity of yeast was 1.2 g, the amount of water was 51.19 mL, the temperature of fermentation was 35.75 ℃, the time of fermentation was 43.65 min. The optimum process parameters of Jiaozi frozen steamed bread dough were: the quantity of Jiaozi was 8.33 g, the amount of water was 49.99 mL, the temperature of fermentation was 35.86 ℃, the time of fermentation was 123.36 min..When the ratio of yeast mixed with Jiaozi was 4:1 and the time of fermentation after unfreezing was 45 min, the appearance of frozen dough was better and the sensory score of steamed bread was higher. Comparison of three different leavening agent to produce frozen steamed bread dough shown that the skin of yeast frozen dough was prone to cracking and collapsing, the quality of steamed bread was not stable; The skin of frozen dough which was added the right amount of Jiaozi was smooth and not easy to crack and collapse, but the power of fermentation was weak and needed longer fermentation time; The skin and flavor of mixed fermention frozen steamed bread dough was better a lot than using pure yeast, at the same time greatly shorten the fermentation time after unfreezing.2.The sensory score of Jiaozi frozen steamed bread dough was highest when the freezing temperature was- 35 ℃. The fermentation capacity of frozen dough and the specific volume and sensory score of steamed bread were decreased gradually with storage time. The optimum thawing method was the constant temperature and humidity compared with other two kinds of thawing methods.3. The optimum compound food additives formula of Jiaozi frozen steamed bread dough were: DATEM 0.2%, xanthan gum 0.2%, alpha-amylase 5.59 mg/kg,Vc 31.46 mg/kg. The optimum compound food additives formula of mixed fermention frozen steamed bread dough were: DATEM 0.15%, sodium polyacrylate 0.05%, Xylanase 25.73 mg/kg, trehalose 3.65%.4.The main flavor compounds in fresh steamed bread and frozen steamed bread dough were alcohols and hydrocarbons; The different kinds of fermention agents greatly influence the flavor of steamed bread, the flavor substances of mixed fermentation frozen steamed bread dough was the most, and Jiaozi frozen steamed bread dough was second, yeast frozen steamed bread dough was the least. Compared the fresh steamed bread and frozen steamed bread dough making with the same fermention agent found that frozen had an effect on the relative content of the flavor substances.5.The internal structure of yeast frozen steamed bread dough was larger and uneven;when adding additive the internal structure improved significantly and protein combined with starch closely; Whether or not adding compound additive,the internal structure of Jiaozi frozen steamed bread dough was uniform and the empty form was small;The size of the internal structure of mixed fermention frozen dough was between yeast and Jiaozi. Whether or not adding compound additive, the internal structure of Jiaozi steamed bread dough was best,and mixed fermentation was second, yeast was the worst; which add composite additive can improve the internal structure of frozen dough significantly.