Survey on conjugated linoleic acid (CLA) content and fatty acid composition of Grana Padano cheese produced in different seasons and areas

Abstract

A study was carried out to determine the content of conjugated linoleic acid (CLA) and fatty acid composition of Grana Padano P.D.O. (Protected Designation of Origin) Italian cheese. Samples were obtained from spring and summer cow's milk in different areas of Grana Padano production district and from all present dairies. In particular, 253 samples of lowland-hill Grana Padano (LH-GP) were analysed: 137 produced from spring milk, and 116 from summer milk. Forty-three mountain Grana Padano (M-GP) samples were also analysed: 25 obtained from spring milk, and 18 from summer milk. The results were subjected to statistical analysis; a factorial arrangement was used, and the fixed effects in the model included season, the manufacturing area of the Grana Padano cheese, and the first order interaction (season x area). Further; cheese beta-carotene concentration was measured in a representative number of summer samples (32), selected according to the CIA level (9 with CLA concentration <5; 10 with CIA value ranging from 5 to 7; 13 with CIA level >7 mg/g total fat), in order to investigate the correlation between CIA content and beta-carotene concentration.M-GP had higher levels of CIA, vaccenic (TVA) and a-linolenic (LNA) acid than LH-GP. CIA concentrations increased from spring to summer both in M-GP and LH-GP. This rise was greater in M-GP showing an effect of interaction between season and production area (P<0.001). An effect of first order interaction (P<0.001) was also seen for TVA with values increasing from spring to summer in M-GP, whereas there only was an effect of the manufacturing area on LNA. During summer, M-GP had the highest polyunsaturated fatty acids (PUFA) percentage. An increase in PUFA from spring to summer was observed only in M-GP (first order interaction, P<0.001). The saturated fatty acids (SFA) decreased from spring to summer both in LH-GP and M-GP and with major entity in M-GP (first order interaction, P<0.001). The beta-carotene concentration resulted positively correlated with CIA level (r=0.92; P<0.01) in summer cheese. The present results underline the role of mountain cheese obtained from summer milk as a natural source of CIA and beneficial fatty acids for human health.