Composition, indigenous proteolytic enzymes and coagulating behaviour of ewe milk as affected by somatic cell count.

This study was undertaken to assess the effect of somatic cell count in ewe milk on i) composition and hygienic traits; ii) plasmin, cathepsin and elastase activities; iii) leukocyte differential count; iv) renneting parameters. Individual ewe milk samples were grouped according to somatic cell count (SCC) into five classes: SC300 (<300 000 cells/ml), SC500 (from 301 000 to 500 000 cells/ml), SC1000 (from 501 000 to 1 000 000 cells/ml), SC2000 (from 1 001 000 to 2 000 000 cells/ml) and SC>2000 (>2 001 000 cells/ml). Individual milk samples were analysed for pH, chemical composition, microbial features, indigenous proteolytic enzymes, differential leukocyte population, and renneting parameters. Milk yield, lactose, protein, non casein nitrogen, microbial features were affected by SCC level. Plasmin and elastase activities were the highest in samples with more than 1 000 000 cells/ml; plasmin had intermediate values in samples with 300 000 to 1 000 000 cells/ml and the lowest in samples with less than 300 000 cells/ml of milk. Cathepsin D showed significantly lower values in SC300 and SC1000 classes than in SC500, SC2000 and SC>2000 classes. The highest percentages of lymphocyte were found in samples with less than 1 000 000 cells/ml, while the highest levels of polymorphonuclear leukocyte were found in samples with more than 1 000 000 cells/ml of milk. Longer clotting time was found in SC>2000 samples, while reduced clot firmness was observed in SC500 and SC>2000 samples. Results on milk yield and on compositional parameters evidenced an impairment of udder efficiency in ewe milk samples starting from 300 000 cells/ml. Plasmin activity in milk can be considered as a marker of the synthetic and secreting ability of the mammary gland; furthermore plasmin and elastase were consistent with the health status of the udder. Finally cathepsin D played a role in the worsening of renneting properties of ewe milk.

Influence of milk quality and production protocol on proteolysis and lipolysis in Monti Dauni Meridionali Caciocavallo cheese.

The aim of this study was to assess the effect of milk source and of cheese production protocol on proteolytic and lipolytic pattern of cheese during ripening. The study involved six dairy factories located in Monti Dauni Meridionali area of Southern Italy; three dairy factories processed the milk produced by their own cow herds, while the other three dairy factories processed the milk collected in other dairy farms located in the neighbouring area. Cow milk processed to cheese had different nutritional parameters and hygienic quality. Caciocavallo cheese showed differences in the evolution of proteolysis during ripening and in the intensity of the lipolytic process detected at the end of ripening. The main factors influencing Caciocavallo cheese features were the quality of the starting milk, differences in technological steps such as milk heating, type of starter cultures and coagulant used.