Abstract:

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.

摘要：

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。