Effect Of Wheat Flour Quality On Chinese Steamed Bread Stale And Research On Chinese Steamed Bread Anti-staling

The objective of this paper was to explore the effect of wheat starch and wheat protein on texture deterioration of Chinese steamed bread crumb through analyzing the correlation between the quality characteristics of wheat flour and texture changes of Chinese steamed bread during storage. At the same time, studied the mechanisms of crumb hardening and loss of elasticity. At the latter part of this paper, effects of the additives on the anti-staling of Chinese steamed bread were dicussed. The main results of research are as follows:1. The significant correlation between sensory evaluation and instrument analysis was found. So we concluded that the physical attributes of Texture Analyser such as Hardness /resilience/stress relaxation could be used as the indexes which could reflect the rule of texture deterioration of Chinese steamed bread crumb during storage.2. Based on Avrami equation, we applied the non-linear regression analysis in dealing with the texture changing curve . Four dynamic parameters were achieved ,for example k_T/n_T/t_o/t_∞,. And also we could get k_R/ n_R/ R₀/ R_∞ or k_SR / n_SR/ SRo / SRx,. The experiments were done to verify the feasibility of the use of Avrami equation.3. 21 varieties of wheat flours were collected all around the country. Furthermore , the physical chemical properties of flours were analyzed thoroughly. Then Chinese steamed bread were made with these flour samples under the same process conditions. During storage at the room temperature , the crumb of Chinese steamed bread was evaluated by Texture Analyser. As a result, we could obtain texture changing curve of Chinese steamed bread made with different varieties of wheat flour. Based on Avrami equation, we applied the non-linear regression analysis in dealing with these curves. Through studying the correlations between wheat flour quality characteristics and value of texture , we found the wheat flour quality characteristics correlating with Chinese steamed bread staling.4.Through correlation and partial correlation analysis, we could conclude: at the early stage of storage, amylose could accelerate crumb hardening of Chinese steamed bread. Wheat protein could accelerate crumb hardening both at the early stage of storage and the late stage of storage. It was evident that improving the specific volume of Chinese steamed bread could retard the crumb hardening. Amylose and amylopectin content of wheat had no relation with changing rate of resilience of crumb. Good wheat protein quality could retard the increase of changing rate of resilience during the late stage of storage. The activity of α -amylase of wheat flour had a significant positive correlation with the stress relaxation of crumb. Good wheat protein quality could retard the increase of changing rate of stress relaxation of crumb during the late stage of storage. Specific volume had no effect on changing rate of stress relaxation.5. k_T of Chinese steamed bread had a significant positive correlation with the amylose content of wheat flour and wheat protein quality. At the same time, it had an extremely significant correlation with the specific volume of Chinese steamed bread. k_R had a significant positive correlation with the wheat protein quality, and had no correlation with the specific volume and wheat starch quality. k_SR had asignificant negative correlation with starch pasting properties of wheat flour, and had no correlation with starch content of wheat flour and wheat protein quality.6. Retrogradatoin of amylopectin of Chinese steamed bread, specific volume and interaction between wheat gluten and starch, they were three factors which affected the texture hardening rate. If the rate of retrogradation increased, the hardening rate of crumb increased spontaneously. Improving the specific volume could decrease the hardening rate. If the interaction between wheat gluten and starch was intensified, the hardening rate of crumb increased spontaneously.7. Addition of Max-life amylase or A1000 amylase or GMS or SSIVCSL had an effect on decreasing the ultimate...