Effect of Long-Term Storage in Light and Dark at Room Temperature on Physicochemical Characteristics of Some Vegetable Oils

Abstract

This work aims to study the effect of light and darkness during storage (12 months) on some edible oils (palm, sunflower, and soybean) on their physicochemical characteristics, oxidative stability and shelf life. The samples were stored in transparent PET bottles in the presence of light (Under illumination light 800 Lux) and darkness at room temperature. The effect of oxidation on oils during storage under light or darkness was evaluated the free fatty acid, peroxide value, thiobarbituric acid test, induction period, and the fatty acids composition, tocopherols, and tocotrienols. The induction period of the oil samples was 27.4, 9.50, and 5.10 h for palm, sunflower, and soybean oils, respectively. The percentages of free fatty acids increase with increased storage time; the highest values in light storage were (0.25, 0.70, and 0.85%) while in dark storage, they were the lowest (0.18, 0.37, and 0.41%) for palm, sunflower, and soybean oils, respectively. As a result, light leads to an accelerated breakdown of unsaturated fatty acids, causing palm, sunflower, and soybean oils to form hydroperoxides of 7.7, 11, and 11.9 meq O 2 /kg oil, respectively. In contrast, samples stored in the dark produced 5.5,