Effect of intermittent heating in the laboratory on some of the physical and chemical properties of different types of refined oils

ABSTRACT

The heating performance of refined, bleached and deodorised sunflower oil, corn oil, cottonseed and sunflower oils were assessed. The quality changes in oils during intermittemt heating at 190 +/- 5°C for 10 hours per day for 5 consecutive days were determined. The change occurring in these oils as a result of thermal and oxidative decomposition during heating were evaluated. Refractive indices, viscosity free fatty acid content, p-anisidine and% polymers of both oils increased during heating, however, peroxide value, smoke point and iodine value decreases, color of oil changed gradually to dark brown from light yellow with increased heating time. Overall, the results indicated that both oils had reached the end of its useful life after 30 hours