Effect of cryoprotectants and storage temperatures on survival of bifidobacterium in corn milk powder, milk powder, sucrose and maltodextrins

Abstract

Bifidobacterium lactis was isolated and gram stained to determine the strain from commercial Bifido powder product purchased from local company using MRS medium supplemented with L-cystein which was indicated as selective medium for Bifidobacterium growth. Viable cells count of Bifidobacterium lactis in commercial product reached 108CFU/g that satisfied standard of probiotic density in food product. Skim milk 14% and a mixture of sucrose 4%, trehalose 4% and skim milk 6% were selected to be cryoprotectants for Bifidobacterium freeze drying process. Cryoprtectant contained sucrose, trehalose and skim milk showed better protective effect for maintaining up to 84% survival rate of freeze-dried Bifidobacterium. This study also investigated on the effect of corn milk powder, milk powder, maltodextrin and sucrose as carriers for storage freeze-dried Bifidobacterium. Corn milk powder contained both protein and carbohydrate showed the highest survival rate of 73% compared with the other carriers tested at 250C; it also maintained similar survival rate as other carriers at 40C which was determined to be the appropriate storage temperature for freeze-dried Bifidobacterium through results of 85% survival rate after 30 days of storage. Key words: Bifidobacteriumlactis, cryoprotectants, powdercarriers, freeze drying.