Optimization of the viability of probiotics in a fermented milk drink by the response surface method

Abstract

Growth promoters were added to skim milk to retain the viability of Lactobacillus acidophilus and Bifidobacterium longum to help the product meet the "therapeutic minimum" at the time of consumption. The experiments were divided into two parts. The first part of the study used chicory inulin, isomalto-oligosaccharides and sucrose to investigate the effects of sugars on the activity of L. acidophilus and B. longum. The results indicated that the addition of isomalto-oligosaccharides stimulated growth of L. acidophilus and B. longum, resulting in a higher level of the probiotics after one month storage and yielded better β-galactosidase activity during fermentation. The second part studied the effects of three growth promoters on the viability of the probiotic cultures and the response surface method was employed to find the optimal ratio for addition of the growth promoters. The optimal ratio for added calcium gluconate, sodium gluconate and N-acetylglucosamine in fermented milk drinks were established. The response surface method proved to be a very effective way of optimizing the activity of probiotic cultures when developing a new fermented milk drink.