illustrates the changes in yogurt pH, which decreased to almost the same extent for all the different incubation starter
cultures and the blank group. During the 21 storage periods, the pH of an entire sample was greater than 4.0, indicating that
L. casei AST18 has weak post-acidification capability. The pH of 2% AST18-added sample was 0.14 units higher than that of the blank group.