Fatty acid composition and nutritional value of fat in three PDO ewe's milk Portuguese cheeses.

摘要

The composition and nutritional quality of fat in 3 Protected Designation of Origin (PDO) Portuguese ewe cheese varieties, namely Azeitao, Nisa and Evora, were determined. Fatty acids (FA) composition of cheese and raw cheese milk was determined using GC and individual CLA isomers were analysed using Ag+-HPLC. Fat from Azeitao, Nisa and Evora cheese varieties showed some differences in FA composition, in particular contents of oleic were 15.4, 17.1 and 19.7 g/100 g, respectively, for Azeitao, Evora and Nisa cheese varieties with extended ripening. Also, some differences were observed in CLA isomer contents, with total CLA concn. reaching 1.15 g/100 g for Nisa cheese, while Azeitao cheese had a lower total CLAconcn. of 0.90 g/100 g. Contents of oleic and stearic acids, monounsaturated fatty acids (MUFA) and CLA were significantly higher for Nisa cheese. Also, significant differences were found between milk and cheese samples, especially for MUFA (21.0 g/100 g for milk and 17.5 g/100 g for 3 month old cheese) and trans fatty acids (3.98 g/100 g for milk and 4.57 g/100 g for 3 month old Azeitao cheese). Contents of the 2 major CLA isomers (cis-9,trans-11 and trans-7,cis-9) were also affected by cheesemaking, particularly for Nisa cheese, as suggested by the significant differences obtained for cis-9,trans-11 levels (68.7 mg/g of fat for milk and 73.8 mg/g of fat for 3 month old cheese) and for trans-7,cis-9 levels (15.8 mg/g of fat for milk and 10.1 mg/g of fat for 3 month old cheese). In addition, the relatively high contents of CLA and low values for the n-6/n-3 ratio suggest good health-related parameters. However, the PUFA/saturated fatty acids (PUFA/SFA index) ratio of 0.06 was consistently below recommended guidelines for the human diet (0.45).