Traditional Zhengmianpi Process Conditions Optimization And The Quality Change

Zhengmianpi is a kind of Chinese traditional snack, which is, used wheat starch as raw materials. With the increasing development of Chinese fast food industry, the customers’ needs on zhengmianpi continue increased. The industry has to pay attention to the production of zhengmianpi. At the same time, market also raises higher requirements to the shelf life and quality of zhengmianpi. The main problem of industrial production is how to extend the shelf life. We intensively studied processing, preservation and quality control of the traditional zhengmianpi.First, the experiment used sensory analysis and texture analysis to study the food and other aspects of quality of preservation under different water content, kinds of gum, and amount of starch and amount of consumption. Then it explores the influence of temperature on four represent zhengmianpi quality during storage. Last, we examine the quality changes on zhengmianpi after vacuum packaging. The main results are listed below:(1) Zhengmianpi processing optimization. By single factor experiment, orthogonal experiment to optimize each step of the process parameters to determine the optimum conditions steamed dough. In sensory analysis test, we found when the water content arrives at 54.5%; the zhengmianpi have highest score. And this water content is as same as the water content in market sold zhengmianpi. Through texture analysis for five different moisture content samples, the higher moisture content, the more soft of the sample is. Compared with the sensory test and texture analysis, we determine the water content at 54.5% and process the further experiments. Parameter optimization: by single factor test, select was 2%- 4% potato starch, starch acetate, glutinous rice flour, and added in an amount of 0.2%- 0.4% konjac gum orthogonal test. We used principal component analysis to process the results of orthogonal,and received the best quality result at starch acetate(4%), konjac gum(0.2%). Considering the economy, low consumption, high quality selection principles, selecting potato starch(added amount 3%, konjac gum(added amount 0.2%) as the best combination.(2) Temperature effects on zhengmianpi’s quality. In shelf life time, with the temperature increased, the sensory test score of cold zhengmianpi got decreased. The zhengmianpi lost majority of water content; the amount of bacteria and molds significantly increase. Thoughthe texture analysis, the hardness and chewiness of zhengmia pi significantly increase at low temperature(4℃). When the zhengmianpi was stored in high temperature environment, the parameter of texture analysis did not have major changes. The zhengmianpi are difficult to get mold and deterioration at low temperature(4℃).(3) Vacuum packaging and quality change of new formula zhengmianpi. Sensory analysis test results stated with the increasing number of storage time, the scores slightly decreased. There is a significant change of sensory test score on the sixth day. Through observation of zhengmianpi, we did not find any breakage happened in the zhengmianpi. The gumminess, chewiness and elasticity of vacuum packaging zhengmianpi got decreased with the time increasing. The hardness and elasticity do not have significant changes. With the time increasing, the shear stress and tensile deformation change significantly(P<0.05). The strength of shear stress and tensile deformation do not change very much(P>0.05). The total number of colonies in vacuum packages is significant smaller than non-packaging samples.The total number of colonies does not exceed the standard under room temperature in six days observations.