The impact of total somatic cells and polymorphonuclear leucocyte cells on the quality of milk and on the chemical composition of cheese

Résumé fourni par la source

This study investigated the effect of somatic cell count (SCC) and polymorphonuclear leucocytes (PMN) on the processability of milks from individual udder quarters. Four milks of SCC 6x103/ml and 920x103/ml and PMN <1x103/ml and 700x103/ml were selected. The low and high SCC and PMN milks were mixed in various proportions to give four artificial mix milks of SCC and of PMN 200x103/ml and 400x103/ml approximately. All milks were analysed for gross composition, renneting properties and N-fractions. Miniature cheeses were manufactured and analysed for composition after 30 d and for proteolysis after 30 d and 90 d of ripening. Fat and protein contents of the milks generally decreased with increasing SCC and PMN and there was no effect on Nfractions in the milks or on total solids, moisture, NaCl or pH in the miniature cheeses. Elevated SCC and PMN had a negative effect on rennet coagulation of milk. The urea-PAGE electophoretogram indicated that the patterns of proteolysis differed quantitatively and qualitatively with increasing milk SCC and PMN during cheese ripening. High SCC and PMN milk resulted in reduced levels of residual intact αs1- and β-caseins, indicating cell-associated proteinase activity. In conclusion, high SCC and PMN milks had inferior composition and processing characteristics.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.