面包酵母冻干粉保护剂筛选及其生物活性分析

目的:优化真空冷冻干燥过程中保护剂配方，得到发酵性能较好的面包酵母3G-28冻干粉。方法:在对脱脂奶粉、蔗糖、吐温?80、阿拉伯胶、β-环状糊精、甘油单因素实验基础上，采用响应面实验对复合冻干保护剂的配方进行了优化，并对酵母冻干粉的发酵力、海藻糖含量、蔗糖酶活力以及发酵液中的风味物质进行了研究。结果:各因素对面包酵母冻干粉活菌数量影响顺序为:甘油浓度 > 蔗糖浓度 > 脱脂奶粉浓度 > β-环状糊精浓度；最佳复合冻干保护剂的配方为:甘油4.7%，脱脂奶粉20%，β-环状糊精15%，蔗糖5%；面包酵母冻干粉活菌数量为36.89×109 个/mL。面包酵母3G-28冻干粉的发酵能力为214 mg/h/g干酵母，海藻糖含量为44.22 mg/g干酵母，蔗糖酶活力20.27 U/g干酵母，与市售酵母菌冻干粉和初始菌株酵母冻干粉相比表现出较高的生物活性。在风味物质方面，面包酵母3G-28冻干粉与其它两者相比醇类的含量最高，表现出了良好的实用性。结论:本文探讨了面包酵母3G-28冻干粉的最佳冻干保护剂配方，得到了生物活性较优的面包酵母冻干粉，在改善面包产品品质及微生物工业化应用中具有很好的前景。

Screening of Protective Agent and Bioactivity Analysis of Bread Yeast Freeze-dried Powder

Objective:The formulation of protective agent added in vacuum freeze-drying process was optimized to obtain bread yeast 3G-28 freeze-drying powder with good fermentation performance.Methods:On the basis of single factor experiments of skim milk powder,sucrose,Tween-80,Arabic gum,cyclodextrin and glycerin,the formula of compound freeze-drying protectant was optimized by response surface experiment,and the ferment power,trehalose content,sucrase activity and flavor in fermentation liquid of yeast freeze-drying powder were studied.Results:The order of influence of each factor on the number of viable bacteria in bread yeast freeze-dried powder was as follows:The concentration of glycerol>the concentration of sucrose>the concentration of skim milk powder>the concentration ofβ-cyclodextrin.The formula of the best compound freeze-drying protective agent was as follows:Glycerin 4.7%,skimmed milk powder 20%,β-cyclodextrin 15%,sucrose 5%.The viable quantity of bread yeast freeze-dried powder was 36.89×109 PCS/mL.The fermentation capacity of baker's yeast 3G-28 freeze-dried powder was 214 mg/h/g,the content of trehalose was 44.22 mg/g,and the activity of sucrase was 20.27 U/g.Compared with the freeze-dried powder of commercially available yeast and the freeze-dried powder of the initial strain of yeast,the yeast showed higher biological activity.In terms of flavor,the content of alcohol in bread yeast 3G-28 freeze-dried powder was the highest compared with the other two,showing good practicability.ConclusionThe optimum formulation of the baker's yeast 3G-28 freeze-drying powder was studied,and the baker's yeast freeze-drying powder with better biological activity was obtained,which had a good prospect in improving the quality of bread products and in the application of microbial industrialization.