Study On Quality Evaluation,wheat Flour Selection And Processing Of Southern-style Steamed Bread

Steamed bread,as the Chinese traditional fermented wheat food,is made of flour,water and yeast and so on by shaping,fermentation and steaming.Steamed bread is generally divided into southern-style steamed bread and northern-style steamed bread becaues of the diffierence of regional culture and dietary habits.The difference between the two kinds of steamed bread is that sugar,baking powder,shortening and other accessories are usually added to southern-style steamed bread,but salt or alkali and other accessories are added to northern-style steamed bread.In terms of the sensory characteristics,southern-style steamed bread emphasizes soft,sweet taste and palatability,which is also different from the compact structure and strong bite of northern-style steamed bread.On account of the quality of southern-style steamed bread is mainly based on sensory evaluation without scientific and objective evaluation system and unstablethe quality of products due to experimental wheat flour selection and processing technology,a comprehensive quality evaluation system of southernstyle steamed bread were stablished by principal component analysis,the raw material selection model of southern-style steamed bread was established and processing technology was optimized in this study.Providing theoretical and practical reference for producing high-quality southern-style steamed bread was the purpose.The main research contents and results are as follows:1、Study on quality evaluation of southern-style steamed breadThe scientific quality evaluation of southern-style steamed bread was the basis of the research on Wheat flour selection and optimization of processing technology.In order to establish quantifiable quality evaluation standard for southern-style steamed bread,the southern-style steamed bread was prepared by 20 kinds of flour according to the unified standard processin,the relationship of sensory evaluation between specific volume,chromaticity value L and texture quality was analysised by linear partial least-squares regressionanalysibi-plo and correlation analysis,principal component analysis method was used to construct the quality evaluation system of the southern-style steamed bread.The comprehensive score of southern-style steamed bread was calculated and cluster analysis was carried out to determine the range of key indexes for quality evaluation of southern steamed bread.The results showed that there were significant(p<0.05)correlations between sensory evaluation,chroma value L and texture quality.The comprehensive score formula of quality evaluation obtained by principal component analysis is Y=0.241ZX1+0.378ZX2–0.318ZX3+0.150ZX4+0.171ZX5.besides ZX1 means specific volume,ZX2 means chroma L value,ZX3 means hardness,ZX4 means springness and ZX5 means adhesiveness which were standardized.According to the clustering analysis of the comprehensive score of southern-style steamed bread,it was found that the specific volume of the good-quality southern steamed buns should be greater than 3.21 m L/g,the chroma L value should be greater than 86,the elasticity should be greater than 0.9,the stickiness should be greater than5.28 g·s,and the hardness should be lower than 868 g.2、Study on wheat flour selection for southern-style steamed breadOn basis of the southern-style steamed bread quality evaluation system,the influence of physical and chemical properties,farinographical properties,gelatinization properties,pasting properties of 20 kinds of wheat flour and and the specific volume chromaticity L value,hardness,elasticity,viscosity and comprehensive quality score of southern-style steamed bread were investigated,the wheat flour material selection model of southern-style steamed bread was established by stepwise regression analysis,the steamed bread quality correlation wheat flour indexs were selected and threshold range of Correlation index of wheat flour for suitably processing the southern steamed bread were got by clustering analysis.The results showed there were significant correlation between the ash content,falling value,peak viscosity,formation time,stabilization time,weakening value,elongation,pasting area,pasting ratio maximum pasting ratio of wheat flour and comprehensive score of southernstyle steamed bread.The raw material selection model of southern-style steamed bread was determined: Y comprehensive of southern-style steamed bread =-7.139 +0.050 X extensiblelanguage-0.255 Xformation time+0.001 Xpeak viscosity(R2=0.914).The correlation indexes affecting the comprehensive score of southern steamed buns were extensiblelanguage > peak viscosity > formation time,the suitable elongation of wheat flour for processing southern-style steamed bread should be greater than 142 mm,the formation time should be shorter than 3.8min,and the peak viscosity should be greater than 1203 Pa·s.3.Study on processing technology of southern-style steamed breadNo.6 wheat flour which is suitable for making southern-style steamed bread was choosed as raw material,the effects between flour-mixing time,rolling times,roller width,fermentation time,fermentation temperature,fermentation humidity and specific volume,colouring L value,hardness,elasticity,adhesiveness and comprehensive quality of southernstyle steamed bread were investigated,the comprehensive quality score of southern-style steamed bread was regarded as the evaluation index to get the optimum technological conditions by single factor and orthogonal experiment and.According to the orthogonal test results,the order of four factors affecting the quality of southern-style steamed bread is:rolling times > fermentation time > fermentation temperature > fermentation humidity >flour-mixing time > roller width.There were a significant effect between rolling times and the quality of southern-style steamed.The optimum technological parameters for processing southern-style steamed with flour-mixing time 3min,rolling times 12,roller width,fermentation time 30 min,fermentation temperature 40℃,fermentation humidity 80%.Under these conditions,the comprehensive quality score of southern-style steamed bread was 3.26 which was the best.