Changes in free fatty acids during ripening of idiazabal cheese manufactured at different times of the year

Lipolysis was studied in cheeses manufactured from raw ovine milk in winter, spring, and summer, with no starter culture added, up to 180 d of ripening. Total amounts of free fatty acids (FFA) after 180 d of ripening were significantly higher in winter than in spring or summer. The major FFA in winter were C-10:0 (3363 mu moles/kg), C-4:0 (3309 mu moles/kg), C-18:1 (3187 mu moles/kg), and C-16:0 (2602 mu moles/kg). The amounts of all FFA in cheese decreased as the cheesemaking period progressed from winter to summer with C-10:0 exhibiting the largest decrease (72.1%) and C-18:1 the smallest decrease (22.8%). The amounts of FFA shorter than C-12:0 were significantly higher in winter than either in spring or summer. The percentage of volatile (C-4 to C-8), medium (C-10 to C-14), and long-chain FFA (greater than or equal to C-16) changed during ripening: in winter and spring volatile FFA increased fi om 15% (d 1) to 30% (d 90 and 180) of the total, while long-chain FFA decreased from 55% (d 1) to 40% (d 180) of the total. In contrast, in summer, the percentages of volatile and long-chain FFA after 180 ripening d were 25 and 50% of the total, respectively. We concluded that winter cheeses were different fi om summer cheeses. Acetic acid increased during the first 90 d of ripening to a final concentration of 26,500 mu moles/kg, the amount of which was independent of the time of the year.