Abstract
Fatty acid compositions, vitamin A, and tocopherols in the butter lipid of the purebred of yak animal were determined by GLC and HPLC. The cholesterol content of yak butter and lipid oxidation kinetics were investigated by GLC and gravimetric methods. The butter produced from yak milk exhibited a strong flavor. This was caused due to the presence of a high concentration of short-chain saturated fatty acids in this butter. The major fatty acids in yak lipids were 16：0, 18：1, 14：0, 18：0, 4：0 and 8：0 in descending order. Retinol content in yak butter was 402.3 μg/100 gm fat. Alpha (α-) tocopherol in yak butter was higher (2.6 mg/100 gm fat) than in cow butter (1.9 mg/100 gm fat), although γ-tocopherol was significant in cow butter (440 μg/100 gm fat). Tocopherols (β- and δ-forms) were found in insignificant amounts in yak and cow butter. Cholesterol content in yak butter was pronounced (325 mg/100 gm fat) than in cow butter (223 mg/100 gm fat). The cow milk lipid oxidation rate was faster and higher compared to the yak milk lipid. Polar lipid content in yak butter lipid was higher than in cow butter lipid.
