Interaction of edible vegetable oils with visible light: implications for food quality

The practice of exposing edible vegetable oils to light and the effect on food quality was the focus of this study. Palm and groundnut oil were studied under the influence of different wavelengths of light corresponding to red, blue, and green light for about a period of one month during which the acid values, free fatty acid values, peroxide values, and iodine values were monitored. Results indicated that both acid values and free fatty acid values of the two oil types increased directly with light in the order of red > blue > green light respectively. Second, light had barely little effect on the peroxide values of the two oils during the storage period. Third, the light had a weak effect on the iodine values of the two oil types studied. Fourth, groundnut oil was safer for consumption than palm oil after a long period of exposure to light. It was concluded that indiscriminately exposing these oils to light affected their quality as it led to increased hydrolysis of triglycerides. It was recommended that oils should be packaged in amber containers to limit the absorption of incident light.