Effect of milk pasteurization on lipolysis during ripening of ovine cheese manufactured at different times of the year

Abstract

Lipolysis was studied in cheeses manufactured with pasteurized and raw ovine milk with a starter culture added in winter, spring and summer, up to 180 d of ripening. Pasteurized milk cheeses had significantly lower levels of lipolysis than raw milk cheeses in winter after 180 d of ripening and in spring both after 90 and 180 d of ripening. The relative amounts of individual FFA after 180 d of ripening changed from winter to summer, both in pasteurized and in raw milk cheeses. In pasteurized milk cheeses made in winter the predominant FFA were C18:1 (2152 ± 386 μmol·kg-1), C4 (1954 ± 354 μmol·kg-1), C16 (1541 ± 406 μmol·kg-1) and C10 (1452 ± 188 μmol·kg-1). In contrast, in pasteurized milk cheeses made in summer C16 (2860 ± 1305 μmol·kg-1) and C18:1 (2677 ± 973 μmol·kg-1) were the major FFA. The percent FFA composition of both types of cheeses changed during ripening: short-chain (C4 to C10) FFA increased from approximately 25% to approximately 40 to 45%, whereas long chain (≥ C16:0) FFA decreased from approximately 55% to approximately 40 to 45% in winter and spring. However, in both types of cheese made in summer long chain FFA represented 52% and volatile FFA represented approximately 28 to 32% of the total after 180 ripening days. Milk pasteurization reduced the levels of acetic acid by 99% after 90 ripening days at the three times of the year studied.