摘要
通过真空冷冻干燥法制备乳酸菌发酵剂,具有活菌数高、发酵活力强、遗传稳定性好等优点,但也会对菌体造成一定的损伤。本文通过分析冷冻干燥过程中细胞膜通透性、细胞膜流动性、酶及蛋白质类物质以及遗传物质等的变化阐述了真空冷冻干燥对乳酸菌造成损伤的相关机制。得到结论如下:在冷冻干燥过程中,冰晶的形成以及磷脂分子的相转变会导致膜的通透性增加;细胞膜脂肪酸成分的改变会造成膜流动性的变化;酶活力的降低及相关蛋白的变性会造成菌体的代谢和生长速率受到影响;DNA结合蛋白结构的改变以及碱基对间的氢键断裂导致DNA超螺旋结构的破坏,这些都会导致乳酸菌发酵活力的下降,甚至死亡。
Lactic acid bacteria （LAB） starter cultures prepared by freeze-drying exhibit the advantages of high viability, activity and genetic stability. But the freeze-drying process usually has some undesirable effects. In this paper, the changes in cell membrane permeability, cell membrane fluidity, enzymes, proteins and genetic materials during freeze-drying are analyzed to elaborate systematically the injury mechanisms of freeze-dried LAB. As results, it is concluded that the mechanism by which freeze-drying causes physiological damages to LAB is mainly attributed to four aspects： the formation of ice crystals and the phase transition of phospholipids, leading to increased membrane permeability; the alteration of cell membrane fatty acid composition, influencing cell membrane fluidity; the decrease of enzyme activity and the denaturation of related proteins, affecting cell growth and metabolic rates; the structural changes of DNA-binding proteins, and the rupture of the hydrogen bonding between base pairs, resulting in the destruction of DNA supercoiling. These physiological damages may lead to decrease in the viability of lactic acid bacteria, or even cell death.
作者
李明慧
尚一娜
霍麒文
陈境
张晓宁
邢叶妮
杨姝玉
王俊国
LI Minghui;SHANG Yina;HUO Qiwen;CHEN Jing;ZHANG Xiaoning;XING Yeni;YANG Shuyu;WANG Junguo(Key Laboratory of Dairy Biotechnology and Engineering,Ministry of Education,Key Laboratory of Dairy Products Processing,Ministry of Agriculture and Rural Affairs,College of Food Science and Engineering,Inner Mongolia Agricultural University,Hohhot 010018,China)
出处
《食品科学》
EI
CAS
CSCD
北大核心
2018年第19期273-279,共7页
Food Science
基金
国家自然科学基金地区科学基金项目(31660456)
内蒙古自然科学基金项目(2015MS0306)
现代农业产业技术体系建设专项(CARS-36)
关键词
真空冷冻干燥
乳酸菌
损伤机制
乳酸菌活力
freeze-drying
lactic acid bacteria
injury mechanism
viability of lactic acid bacteria
