USING WHEY PROTEINS TO IMPROVE QUALITY OF YOGHURT MADE FROM COW'S MILK.

This study were investigate the effect of fortification yoghurt made from cow's milk with whey protein hydrolysate" six treatments" that made by fortified cow's milk with 3%NFDM (control) and five treatments that fortified with 0.5,1.0,1.5,2.0 and 2.5% whey protein hydrolysate and other five treatments that made by fortified cow's milk with 3%NFDM (control) and four treatments that fortified with 0.5,1.0,1.5 and 2.0 whey protein whey protein isolate on some chemical, rheological and organoleptic properties of yoghurt with cold refrigerator at12 days of storage, tetratable acidity, total solids, total protein hardness, adhesiveness, cohesiveness, springiness, gumminess and chewiness of yoghurt fortificated with whey protein hydrolysate and isolate were changed significantly it were increased by the rate of adding whey protein hydrolysate and isolate.on the other hand tetratable acidity increased by storage period progressed but total solids, total protein, ash content and fat contentdid not change significantly by storage period progressed,  fat content did not change by adding whey protein hydrolysate and isolate, ash content chang slight by adding whey protein hydrolysate and did not change significantly by adding whey protein isolate, pH decreased by fortification of either whey protein hydrolysate and isolate, syneresis decreased by fortification of either whey protein hydrolysate and isolate until sixth day of storage period then increased at the end of storage period ,  total bacterial counts, streptococci and lactobacilli counts increased by fortification whey protein hydrolysate and isolate until third day of storage period then decreased at the end of storage period,  Scores of organoleptic properties (flavour, body and texture, acidity and appearance) of yoghurt treatments fortified with whey protein hydrolysate at 2% and whey protein isolate at1.5 % and gained the highest scores.