Biochemical parameters and oxidative resistance to thermal treatment of refined and unrefined vegetable edible oils.

摘要

Fatty acid composition, tocopherol content and quality parameters, such as free fatty acid contents, peroxide values and induction time of refined (sunflower, extra-sunflower, soybean, and rapeseed) and unrefined (olive and pumpkin seed) vegetable oils were determined. Extra virgin olive oil had the highest average peroxide value, while unrefined pumpkin seed oil had the lowest. Acid values of unrefined oils were higher on average than those of refined oils. Soybean oil had the highest total tocopherol content and extra virgin olive oil the lowest. Refined oils with higher contents of saturated and monounsaturated fatty acids and lower PUFA contents had relatively high oxidative stability. A negative correlation was observed between induction time and PUFA content. Among the oils investigated, unrefined pumpkin seed oil showed the highest oxidative stability, followed by, in decreasing order: extra virgin olive > high oleic sunflower > rapeseed > soybean > sunflower oil. Oxidative stability of unrefined oils was greater than that of refined oils.