Change of fatty acid profile, including conjugated linoleic acid (CLA) content, during refrigerated storage of yogurt made of cow and sheep milk

Abstract

Changes in conjugated linoleic acid (CLA) concentration, fatty acid profile and chemical composition of yogurts from cow and sheep milk, produced with traditional methods, were determined during a 14-day storage at 5°C. When fatty acid (FA) composition of yogurts was expressed as g/100g of edible portion (EP) saturated fatty acids (SFAs) significantly increased (P<0.05) during storage while monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) showed the opposite tendency in cow milk yogurts. No significant change was observed in SFAs, MUFAs and PUFAs in sheep milk yogurts. When FA composition of yogurts was expressed in g/100g dry matter (DM), SFAs showed a significant decrease during storage (P<0.05). The c-9, t-11 CLA isomer ranged between 0.24 and 0.45g/100g fat in cow milk yogurts, while in sheep milk yogurts between 0.47 and 0.76g/100g fat. During the 14-day storage at 5°C, CLA significantly decreased (P<0.05) at the end of the storage time in cow milk yogurts, while in sheep milk yogurts it significantly increased (P<0.05). n-3 fatty acids showed a significant increase at the end of the storage period (P<0.05) and this increase was more evident in sheep milk yogurts.