Protection mechanisms of sugars during different stages of preparation process of dried lactic acid starter cultures

Sugars are recognized protectants used in the preparation of dried starter cultures for fermented food industries, particularly as additives for the drying media. They increase viability of the starter cultures during drying and storage. This review intends to summarize and discuss their roles in each step of the preparation process. The main topics cover the role of sugars in the induction of compatible solutes and alteration of fermentation metabolites during growing of cells, the reduction of cryo- and thermal injuries and membrane damage during drying, as well as the formation of sugar glass matrices and the prevention of oxidation during storage. In some topics, proposed protective mechanisms together with corresponding inactivation mechanisms have been discussed. The protective hypotheses as such are preferential exclusion, water replacement, hydration force explanation, and vitrification of sugars.