engleski

processing and ripenig properties of Podravec cheese (semi hard type)

The influence of somatic cell count (SCC) on chemical composition, yield, fat and protein recovery in the processing of Podravec (semi hard cheese) was investigated. In addition, the role of plasmin in proteolysis during cheese ripening and relationship of concentrations of plasmin and SCC in milk were investigated. A total of 600 kg of milk was collected from 61 farms and then divided into three groups of 200 kg of milk regarding various SCC (*250 000 mL-1, 250-500 000 mL-1, *500 000 mL-1). Further, each group was divided to two subgroups of 100 kg of milk. One subgroup was treated with urokinase (activator of plasmin) and other was free from urokinase. Milk was processed to cheese Podravec in a pilot dairy of the “Sirela” factory. Proteolysis during ripening was determined in three ways: as percentage of water soluble nitrogen to total nitrogen (WSN TN-1), three acetic acid soluble nitrogen to total nitrogen (TCASN TN-1) and relative density of protein bends on electrophoretograms using urea-polyacrylamid gel electrophoresis. The effect of SCC, urokinase and duration of ripening were analyzed using a split plot statistical model. The deleterious effects of an elevated SCC on chemical composition, yield, fat and protein recovery in processing of Podravec cheese was clear. Cheese made from milk with *250 000 SCC mL-1 was significantly superior to that made from milk with *250 000 SCC mL-1 in most yield and quality characteristics. Proteolysis during ripening showed that plasmin was an important enzyme in proteolysis of the Podravec cheese and treated milk with urokinase increased WSN TN-1 (P=0, 07). Percentage of *-casein was significantly increased in high SCC milk (*500 000 SCC mL-1) treated with urokinase (P*0, 05). Plasminogen/plasmin activity was increased during ripening of cheese produced from high SCC milk as the result of increased concentration of plasminogen/plasmin in high SCC milk.

somatic cell count; Podravec cheese (semi hard cheese); plasmin

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