【作者】 时晓剑； 缪冶炼； 卫昊； 徐红；

【Author】 Xiaojian Shi Yelian Miao~* Hao Wei Hong Xu (State Key Laboratory of Materials-Oriented Chemical Engineering,College of Food Science and Light Industrial Technology,Nanjing University of Technology,Nanjing,Jiangsu 210009,China)

【机构】 南京工业大学食品与轻工学院材料化学工程国家重点实验室；

【摘要】 γ-聚谷氨酸(Y-PGA)是由谷氨酸聚合而成的水溶性物质,可以食用,无色无味,可能显示出较高的抗冻能力。本研究旨在探明γ-PGA对面包酵母的抗冻作用及其机理。首先,将一定量的佰γ-PGA加入酵母细胞液,经-70℃冷冻2h、-18℃冷藏一段时间后,30℃解冻10min。冷冻前和解冻后的酵母细胞数用血球计数板法测定。实验结果表明,酵母细胞存活率在冻藏初期急剧下降,6天之后趋于稳定。γ-PGA对酵母细胞的抗冻作用大于谷氨酸和葡萄糖。添加1%的γ-PGA,酵母细胞存活率从未加抗冻剂时的30.7%提高到62.6%。在此基础上,含有γ-PGA的酵母细胞液的冷冻过程进行DSC分析,讨论酵母细胞存活率与未冻结水含量的关系、更多还原

【Abstract】 Poly-γ-glutamic acid(γ-PGA),a water-soluble polyamide composed solely of glutamic acid,is edible,tasteless and odorless.It is also expected to display high antifreeze activities.The objectives of the present study were to investigate the antifreeze effect ofγ-PGA on bakers’ yeast cell,and to clarify its mechanism.γ-PGA was added to the suspension of ordinary bakers’ yeast cells.Then the suspension was frozen at -70℃for 2 h,stored at -18℃for a period of time,and thawed at 30℃for 10min.The number of yeast cells before freezing and after thawing was examined with the blood cell counting plate method.The experimental results showed that the yeast cell survival ratio decreased at the beginning,and was constant after 6 d during the freeze storage.γ-PGA had greater antifreeze effect on yeast cells than glutamic acid and glucose.The yeast cell survival ratio was increased from 30.7%to 62.6%by adding 1%γ-PGA.Based on these results,the freezing process of yeast cell suspension withγ-PGA was further analyzed by differential scanning calorimetry(DSC)for discussing the relationship between yeast cell survival ratio and unfrozen -water content.更多还原