ASPECTS OF STORAGE DURATION AND GENERATION OF YOGURT AS STARTER IN MAKING YOGURT UNDER ROOM TEMPERATURE

Abstract

To find out how to get good and standard yogurt using yogurt as starter, this
study was conducted to determine storage duration and generation of the yogurt used as starter to make yogurt under room temperature. Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophillus were used to make yogurt under 45°C, to be used as starter. Bacterial growth, pH and acidity were observed every hour. Yogurt refrigerated for 1, 4, 7, 10, 13 and 16 days were then tested as starter at the rate of 5% in making yogurt, incubated at 45°C as well as at room temperature (29°C). Yogurt which was kept for 1 and 7 days were then used as starter to make yogurt under 45°C and room temperature (first generation). Five percents of each 15‘ generation-yogurt was then used as starter for 2"“ generation- yogurt, etc. until 6"‘ generation. Tests for yogurt quality comprised of pH, acidity, moisture content, bacterial count and the presence and identification of Salmonella and Staphylococcus. Factorial analysis of variance followed by Duncan‘s multiple range tests was performed. It was found that yogurt could be used as starter kept under refrigerator temperature for 16 days up to 6"’ generation for making yogurt under room temperature of incubation meeting the standard of quality without
any contamination of undesirable bacteria.