Physicochemical Properties and Microbial Count of Bacterial Survival in Freeze Dried Goat Milk Yogurt Powder

Abstract

Yogurt is a fermented milk product that has a semi-solid texture and has a short shelf life. It must be stored properly in temperature of 4ºC and below to prevent the microbial spoilage due to it high in moisture content and water activity. This study aimed to produce freeze dried goat milk yogurt powder with different percentage of honey and analyse the physicochemical as well as compare the microbial count of bacterial growth in fresh goat milk yogurt and reconstituted goat milk yogurt powder. The four formulations prepared were 6% of sugar (CY), 3% of honey with 3% of sugar (LHY), 4% of honey with 2% of sugar (MHY) and 6% of honey (HHY). The results showed each formulation has significant differences for the physicochemical analysis. The percentage of honey added into the yogurt was affected the pH value of the yogurt which have a range from pH 4.18 to 4.45. Meanwhile the results for colour analysis shown that the yellowness value of goat milk yogurt was increased as the percentage of honey added inside the yogurt was increased, as contributed by dark brown colour of honey. The bacterial survival in CY, LHY, MHY and HHY samples for fresh goat milk yogurt and reconstituted goat milk yogurt powder showed the significant different (p<0.05) with the range from 6.40 to 8.75 log cfu/ml and 5.79 to 8.07 log cfu/ml respectively. Therefore, it can be concluded that freeze drying was a suitable method to produce yogurt powder and LHY sample was the best formulation in producing the highest number of survival bacteria (log cfu/ml).