Effect of Cold Storage and Mixing Various Lactations of Buffaloe's and Cow’s Milk on Some Properties of Yoghurt

Abstract

In this study yoghurt was made from cold stored buffaloe's or cow's milk for 24 or 48 hours. Also, the effect of addition of morning and evening milk to refrigerated stored milk on some properties of yoghurt was studied. Results showed that yoghurt made from buffaloe's milk possessed higher acidity, TS, fat, ash and TN while had lower WSN, WSN/TN, NPN, NPN/TN and TVFA values than those of made from cow's milk. Blending various lactations milks with cold stored milk raised the acidity and TVFA values and lowered the pH values of the resultant yoghurt and had no clear effect on TS, fat, ash, TN, TN/DM, WSN, WSN/TN, NPN and NPN/TN. Refrigerated storage of buffaloe's or cow's milk increased the acidity and TVFA values of yoghurt and had no clear effect on TS, fat, ash, TN, TN/DM, WSN, WSN/TN, NPN and NPN/TN. Yoghurt made from buffaloe's milk contained higher numbers of total viable bacterial count (TVBC), lactic acid (LAB), psychrophilic bacteria, proteolytic, lipolytic, colifom, sporoformers, moulds and yeast. Mixing evening and morning milk with cold stored milk or cooling milk for 24 or 48 hours increased the mentioned microbial groups numbers of yoghurt. Yoghurt prepared from buffaloe's milk had higher score point than that of cow's milk. Adding various lactations buffaloe's or cow's milk to refrigerated stored milk and storing milk at 4°C for 24 and 48 hours had no clear effect on sensory evaluation of yoghurt.