改性酵母蛋白制备混凝土发泡剂及其处理条件优化

Preparation of concrete foaming agent by yeast protein modification and optimization of processing condition

以啤酒酵母菌体为原料,利用超声波法提取酵母细胞内蛋白质,选择干热法、热碱法和酶法对酵母蛋白进行改性处理,通过比较改性前后酵母蛋白的泡沫性能可知:3种方法均对酵母蛋白泡沫性能有一定的改善作用,其中浓度为1.5%Ca(OH)2水解后得到发泡母液的泡沫性能最佳,泡沫体积达到1109.1 mL,稳泡时间达10.1 h。采用响应面实验法中的Box-Behnken设计对影响热碱法改性蛋白发泡体积的3个主要因素[反应温度、反应时间、Ca(OH)2浓度]进行优化,结果表明:当水解温度77.88℃、水解时间2.39 h、Ca(OH)2浓度1.34%时泡沫体积达最大,最大预测值1135.1 mL,实际测得平均发泡体积为1127.2 mL,与模型理论预测值相比相对误差在0.72%,所以采用响应面实验法优化得到的参数准确可靠,具有实用价值。

The release of intercellular protein from yeast cells was proposed for protein modification.Saccharomyces cerevisiae protein isolate modified to improve its foaming ability was tested.Dry-heating treatment,thermal alkaline denaturalization and enzymatic hydrolysis were used,and the best results were obtained by using thermal alkaline denaturalization method with Ca（OH）2 concentration of 1.5%,which increased maximum foam volume to 1109.1 mL,and foam stability time to 10.1 h.According to the Box-Behnken center-united experimental design principles,the method of response surface analysis with 3 factors and 3 levels was adopted.The optimum modification conditions were determined by analyzing the three-dimensional surface plot and contour plot and by solving the regression model equation with Design Expert software,which showed that reaction temperature of 77.88 ℃,time of 2.39 h,and Ca（OH）2 concentration of 1.34% were the best conditions.Under the optimal conditions,the forecasted maximum foam volume was 1135.1 mL,and verified value was 1127.3 mL by confirmative test.The relative error was 0.72%,indicating that the regression equation was valid and reliable.