The pH of the beverages was affected by the homogenization pressure and pH adjustment (5.5, 6.5, and 7.5) before heat treatment (Fig. 3). The samples adjusted to pH 6.5 had little change after heat treatment, but those adjusted to pH 7.5 showed a large drop, to about pH 7.0, after heat treatment for 20 min at 121 °C, regardless of the homogenization pressure. But the samples adjusted to pH 5.5 exhibited a slightly increased pH in the same conditions. The large drop in pH in samples adjusted to pH 7.5 could be due to the loss of positive charges on the protein molecule by the Maillard reaction, which occurs at a relatively high rate in alkali conditions compared to acid conditions.