Effect of Using Different Rates of Donkey Milk and Cow Milk on Physicochemical, Texture and Sensory Properties of Set-Type Yoghurt

Yoghurt is a high consumed fermented milk product which has positive effect on health due to high nutritional value. Donkey milk is rich in nutritional and therapeutic properties and is used in enrichment of various food products. The aim of this study was to evaluate the effect of using different rates of donkey milk and cow milk on quality properties of set-type yoghurt. For this purpose, yoghurt samples were manufactured using different rates of donkey milk and cow milk with the ratios of 100:0, 0:100, 50:50, 75:25 and 25:75, respectively. Yoghurt samples were stored in refrigerator (4±1°C) for 15 days and their physicochemical, texture and sensory properties were evaluated at 1st, 8th and 15th day of storage. The results of different analysis showed that increasing the rate of donkey milk in yoghurt samples caused to significant decrease (p<0.05) in pH, fat (%), protein (%), dry matter (%), water holding capacity (%), viscosity (centipoise), hardness (N) and odor and flavor and significant increase (p<0.05) in acidity (% LA) and syneresis (g/25g). For yoghurt samples manufactured with cow milk and donkey milk with the ratios of 100:0 and 0:100, the amounts of pH were 3.95 and 4.15, acidity were 1.47 and 1.26, syneresis were 8.39 and 6.36 and viscosity were 3890 and 17860 in 15th day of storage. In conclusion, yoghurt samples manufactured from the combination of donkey milk and cow milk at 25:75 and 50:50 ratios had acceptable points regard to physicochemical, texture and sensory properties.