Optimization of Growth and Storage Conditions for Lactic Acid Bacteria in Yogurt and Frozen Yogurt

The optimal conditions for growth and storage of the lactic acid bacteria were studied. Both sucrose (up to 3%, w/v) and skim milk (up to 12%, w/v) increased the number of lactic acid bacteria. However, the effect of sucrose plus skim milk was not superior to that of skim milk alone. The cell number was maximal at pH 5.0-5.5 during the growth of bacteria and at pH 4.63 during the storage period of yogurt. The final cell number of yogurt stored for 150 days at −18 ≈ −12°C was 1/3 of the initial cell number.