Factors affecting quality of white cheese manufacturing From goats milk

Hadeel Sady Ahmad Al karjeh
هديل سعدي أحمد الكرجة
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Al-Quds University
Cheese is produced by conversion of milk from a fluid to a gel (coagulation). Gel formation is a consequence of protein destabilization and may be brought about either by acid such as chymosin, the active component of rennet, quiescent acidification to a PH value close to the isoelectric point of the proteins, or by a combination of acidification and heating. There are problems in the cheese which are produced from goat’s milk first in their stability where there are loss in weight (total solid) during storage period also in their short shelf-life and undesirable aroma and flavour of final cheese which is related to the types of fatty acids that are present in goat’s milk. In Palestine there is a large number of goat's herd where there are trouble for manufacturing of white cheese from their milk and this is related to small yield of cheese also small amount of total solid compared to that produced by using cow’s milk; also cheese from goat’s milk have shelf life shorter than cheese of cow’s milk, for these reasons we found that it is nessecary to solve the problems of goat’s cheese by addition of different materials also using different percentage of mixed cow’s to goat’s milk. In this study, the physico-chemical changes occurring in white cheese produced from goat’s milk, as a result of possible effects of some addition in combining with the ripening period during the life of the experiments were examined. 120 cheese samples were produced in two parts, each part included 60 samples. All cheese samples, in both groups, were made basically by adding rennet enzymes. However, the investigated materials (starter culture, CaCl2, carob latex, and fig latex) were added in certain arrangement to assure that each experiment has one variable. Different mix rations between goat’s and cow’s milk were used to have a comprehensive element of study. iv The cheese were ripened in 15 % brine solution at 4°C for 30 days. Samples were taken from each treatment and analyzed on 2nd, 15th, and 30th day of storage. Sensory evaluation, microbiological analysis (mould, yeast, and coliform) and chemical properties (pH, acidity, salt, fat, moisture and protein content and total solid) of the prepared cheese were determined. Important results found in this study were that mixing goat milk with cow milk decreases the goat flavour its present in cheese product, it increase the protein and total solid contents of the cheese. Cheese made from raw milk mature faster and have higher flavor intensity than cheese made from pasteurized milk. The use of commercial starter cultures in makeing cheese from pasteurized milk results in uniform characteristics of the same cheese made from raw milk. Fig latex addition affected the chemical properties of the cheese where it increaseof the total protein percentage in the final product. Also it affected negativily the sensory properties of the cheese resulting in strong odor, bitterness , less cohesion and gummier texture for cheese. Carob latex addition affected the chemical properties of the cheese where its increase the total solid percentage in the final product. Also Carob latex affected the sensory properties of the cheese where its give.final cheese product with off-white color, however its give cheese with very hard texture.