PHYSICOCHEMICAL PROPERTIES OF YOGHURT FORTIFIED WITH DIFFERENT ZINC SALTS

Fresh buffalo’s milk of ٦٪ fat was heated. each of three zinc salts (zinc gluconate, zinc sulphate and zinc acetate) was added to individual milk sample at levels of 30 mg zn/l milk with the addition to the control treatment. then, cooled, and inoculcated with 3٪ mixed culture of lactobacillus delbrueckii sub sp. bulgaricus and streptococcus salivarius sub sp thermophilus. and incubated at ٤2°c until firm curd was formed at ph ٤٫٦. the resultant yogurt was kept in refrigerator (٦±1°c) for 10 days. results showed a reduction in ph values, lactose content and the wheying off resulting in from the prepared yoghurt which supplemented with zinc salts. whereas, an opposite trend was noticed for acidy, curd tension. while, yoghurt supplemented with zinc acetate recorded the highest value of acetaldehyde content. moreover the zinc sulphate gained the highest viscosity till the 7 th day of storage. concerning the sensory properties, enriching yoghurt with zinc gluconate recorded the highest score in flavor, body & texture.