Survival of Lactobacillus acidophilus Encapsulated as Freeze-Dried Culture under Extreme Conditions

Lactobacillus acidophilus La-1 was encapsulated as freeze-dried culture and its survival rates under various extreme conditions were investigated in this work. The survival rate of the freeze-dried bacteria remained at 87.1% with the viable counts of 2.26×10⁸ cfu/mL, while keeping at pH 2.5 for 2 h, and the micronized culture was also tolerant to 6% NaCl. In 0.1% bile salt medium, the viable counts of Lactobacillus acidophilus La-1 reached to 3.39×10⁹ cfu/mL, and it could also grow exposing to 0.5% bile salt medium. The viable counts were 9.33×10⁷ and 1.03×10⁸ cfu/mL, with survival rates of 44.64% and 49.28%, after keeping in simulated gastric or intestinal juice for 2 h, respectively. These results indicated that the encapsulation of Lactobacillus acidophilus La-1 as lyophilized culture could be quite effective for the bacteria to survive in extreme conditions, and the freeze-dried culture powder might be thus appropriate to be applied in foods or nutritious supplements.