TITLE:
Effect of Lactose on Acid Tolerance of Yogurt Culture Bacteria
AUTHORS:
Behannis Mena, Kayanush Aryana
KEYWORDS:
Lactose, Acid Tolerance, Lactic Acid Bacteria
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.11 No.6,
June
12,
2020
ABSTRACT: Lactose, the sugar naturally present in milk,
provides energy to lactic acid bacteria used in fermented dairy foods.
Increasing concentrations of lactose may improve survivability of lactic acid
bacteria in the dairy foods and in human gut enhancing their probiotic
benefits. Acid tolerance is an important probiotic characteristic. The
objective was to determine the influence of lactose on acid tolerance of yogurt
starter culture Streptococcus thermophiles ST-M5 and Lactobacillus bulgaricus LB-12. The M 17 broth was used for Streptococcus thermophiles ST-M5 and MRS broth was used for Lactobacillus
bulgaricus LB-12. Lactose was
added to both broths at 0% (control), 1%, 3%, and 5% (wt/vol). Both broths were
acidified to pH 2.0. Upon sterilizing and tempering, both broths were
inoculated. Acid tolerance was determined as viable
counts in acidified broths after 120 minutes of incubations. In an incubation
period of 2 hours, dilutions were plated every 30 minutes. Three replications
were conducted. The highest acid tolerance for Streptococcus thermophiles ST-M5 and Lactobacillus bulgaricus LB-12, was observed in lactose concentration
of 3% and 5% (wt/vol).