Abstract:
A decrease in pH is one indicator of the growth of microbes in forming organic acids.
This study aims to determine the effect of the type of lactic acid bacteria and the
fermentation time on the pH value of purple glutinous corn milk and fermented white
glutinous corn milk. Purple glutinous corn milk and white glutinous corn milk are made
from 10% skim milk, 20% sucrose, 0.2% monosodium glutamate (MSG), and 0.2%
vitamin B6 through the pasteurization step at 90oC for 10 minutes, inoculation of
bacteria (Lactobacillus casei and Lactobacillus brevis) as much as 2% and incubated
at 37oC for 0, 24, 48 and 72 hours. The pH values of purple glutinous corn milk and
white glutinous corn milk were measured using a pH meter (Hanna Instruments
H12211, USA). The results showed that the effect of the type of lactic acid bacteria
and the time of fermentation gave significantly different pH values (p<0.05) for
fermented purple glutinous corn milk and white glutinous corn milk.
