Phsico-chemical Characteristics of Traditional Butter Oil Made from Spontaneous Fermentation of Goats’ Milk

Chemical and physical characteristics of goats’ butter oil prepared from naturally fermented goats’ milk, and stored under accelerated oxidation conditions at 63±0.5 ° C for 30 days were investigated. Different concentrations of αtocopherol (2.5-10 mg/100g fat) and 1% of milk phospholipids (PL) were added to goat’s butter oil. Increasing the concentration of α-tocopherol and autoxidation process time significantly (P<0.05) influenced the properties of the butter oil properties. All αtocopherol concentrations protected butter oil against oxidation to some extent and the protection factor depended on the concentration of α-tocopherol used. Increasing the concentration of α-tocopherol added did not affect the fatty acids composition in the butter. Butter oil treated with 10 mg αtocopherol /100g fat was characterized with the highest unsaturated fatty acids (highly protected against oxidation), iodine number, saponification number, acid value and free fatty acids till the end of autoxidation process. Also, slip melting point decreased (p ≤ 0.05) with increasing the concentration of α-tocopherol added, being the lowest with the highest αtocopherol concentration. On the other side, the specific gravity and refractive index showed an opposite trend under accelerated oxidation storage. All textural characteristics (hardness, gumminess, springiness, cohesiveness and chewiness) and dynamic viscosity values significantly decreased (p≤0.05) with extending the accelerated oxidation time, and by increasing the concentration of α-tocopherol used, being the lowest with 10 mg αtocopherol /100g fat till the 30 th day of storage. Generally, direct addition of different concentrations of α-tocopherol and milk phospholipids significantly (p≤0.05) protected butter oil (longer shelf-life of this fat) during the stages of accelerated autoxidation.