The initial average pH of plain yogurt was 4.38 (±0.01) and decreased to 4.24 (±0.02) at the end of the shelf life. The initial average pH readings of the 5%, 10% and 15% stirred fruit yogurts were 4.27 (±0.01), 4.26 (±0.01), and 4.24 (±0.01) respectively, and at the end of the shelf life their pH values were decreased to 4.15 (±0.01), 4.14 (±0.01) and 4.16 (±0.00), respectively