Stability of bifidobacteria in powdered formula

Two stability tests of bifidobacteria in powdered formula were conducted. In a strain comparison test, three kinds of bifidobacterial powders; Bifidobacterium longum BB536, Bifidobacterium breve M-16V and Bifidobacterium infantis M-63 powders, admixed in follow-up formula were used. In a commercial product evaluation, powdered formulas for toddlers containing bifidobacteria sold in the Indonesian market were analysed. When the inactivation rate constant of each sample, which was used as an index of the loss rate, was determined from the stability tests, B. longum was the most stable strain. The mean inactivation rate constant of commercial products was significantly lower than those obtained in strain comparison, although the same strains (B. longum BB536 and B. breve M-16V) were used. A possible reason was the lower water activity of commercial products compared to the follow-up formula. Also, higher storage temperature yielded lower stability in all strains or samples, which obeys the Arrhenius theory.