Effects of Heat-treated Skim Milk on the Texture of Yogurt Curd

Abstract

　The effects of heated skim milk on the physical properties of yogurt curd were determined. The gel strength and water-holding capacity (WHC) of yogurt curds prepared from heated (80℃ and 90℃ for 30 min) skim milk increased significantly relative to that of the yogurt prepared from unheated skim milk. The effects of sodium thiocyanate on the physical properties of yogurt curd were also determined, and the gel strength and WHC decreased as the concentration of sodium thiocyanate increased. These results indicate that the addition of sodium thiocyanate decreased the intermolecular forces between the proteins in yogurt curd, thereby inhibiting the hydrophobic interactions between the proteins. Further, the results suggest that the hydrophobic interactions between proteins and between casein molecules contributed to the increase in the gel strength and WHC of yogurt curds prepared from the heated skim milk.