Yogurt pH and TA were significantly affected by formula and storage (Table 1). Yogurt pH was also affected by formula 9 culture; whereas, yogurt TA was affected by culture only (Table 1). The pH of PE yogurts (4.38) was highest, followed by SA yogurts (4.34) and NS yogurts (4.27); whereas, the TA of PE yogurts (1.48%) was also highest, followed by SA yogurts (1.37%) and NS yogurts (1.23%; Table 2). These results confirmed that PE yogurts had greater buffering ability compared with the SA and NS yogurts. Therefore, some additional factors, other than SA in the PE, contributed to the greater buffering ability of PE yogurts compared with SA yogurts.