Optimal combination of multiple cryoprotectants and freezing-thawing conditions for high lactobacilli survival rate during freezing and frozen storage

摘要

The optimal cryoprotectants combination, freezing rate and thawing temperature were investigated for preservingLactobacillus plantarumandLactobacillus caseiduring freezing and frozen storage. It is indicated that, among all cryoprotectants applied singly, 150?g/L and 100?g/L sucrose provided the best protective effect forL. plantarumandL. casei, respectively (survival rate?=?74.4% and 84.8%, respectively). By using orthogonal experimental design for cryoprotectant mixtures, the mixture of trehalose, sucrose, glycerol and skimmed milk at final concentration of 12.5, 12.5, 37.5 and 25.0?g/L, respectively, appeared to enhance significantly the survival rate ofL. plantarum(92.8%) andL. casei(91.2%). Among all freezing and thawing conditions examined, the survival rate ofL. plantarumwas the highest at a freezing rate of ?10?°C/min and thawing temperature of 0?°C; and that ofL. casei, at a freezing rate of ?1?°C/min and thawing temperature of 0?°C. The cryoprotectant effect exerted by keeping the integrity of cell membrane and therefore maintaining the lactobacilli survival.