OXIDATIVE STABILITY AND SOME FUNCTIONAL PROPERTIES OF GOAT AND CAMEL MILK FAT FRACTIONS

Goat and camel milk fat were fractionated into liquid and solid fractions by crystallization at 15, 25 for goat and 30, 40°c for camel milk fat. Fatty acid profile and functional properties (slip melting point, specific gravity, refractive index, cholesterol content, iodine value, and yield) were analysed for original butter oil and obtained fractions. Stability of fat to oxidation during induction acceleration periods using TBA and polymorphism using x-ray diffraction pattern were also characterized. Fatty acid profile of camel milk fat indicated lower values of total short chain (TSC) and higher values of total long chain (TLC) and unsaturated fatty acids (USF A) compared to goat milk fat. The short chain and unsaturated fatty acids migrate to the liquid fractions being higher at lower fractionation temperature whereas, long chain saturated fatty acids concentrated in solid fractions being increased with increasing the fractionation temperature. Slip melting points were statistically significantly differed among all fractions being higher in camel fractions. Goat milk fat fractions showed higher specific gravity, with lower refractive index, cholesterol content and iodine values compared to camel fat being lowest in solid fractions. Camel milk fat and its fractions were highly stable against oxidation (up to 20 days) and longer shelf-life especially its solid fractions, as compared to goal fill. The liquid fractions of both goat and camel fat exhibited lower stability to oxidation (higher TBA) than their butter oil or solid fractions. The X-ray diffraction pattern of camel milk fat fractions showed different peaks compared to goat fat fractions. Liquid fractions of camel fat showed both p and W polymorphs while liquid goat fat fractions showed only p polymorph. The magnitude of X-ray diffraction peaks increased with increasing the fraction melting point being more pronounced in camel fractions which indicate higher crystallization and stability of camel fat.