Sunflower oil, Soybean oil, Oxidative deterioration, Sunlight storage.

Abstract

The primary objective of the present study was to evaluate the effects of sunlight exposure on the quality and oxidative stability of sunflower and soybean oils. Samples of refined bleached and deodorized soybean oil and sunflower oil, packed in translucent polyethylene terephthalate bottles were exposed to sunlight (exposure period, ca. 10 h daily) over a period of 7 weeks. Control (oils stored at ambient in darkness) samples were also processed, concurrently. The levels of auto and photooxidative alterations in the oils investigated were assessed by determinations of colour, refractive index, peroxide, p-anisidine, conjugated dienes, conjugated trienes, free fatty acid contents and iodine numbers at appropriate intervals. Overall, the magnitude of oxidative changes was more distinct in the case of soybean oil; nevertheless, both the sunlight-exposed oils revealed significantly (p < 0.05) higher deterioration as compared with their respective controls.