Cold fluorescent light as major inducer of lipid oxidation in soybean oil stored at household conditions for eight weeks

Light, temperature, and oxygen availability has been shown to promote rancidity in vegetable oils. However, the contribution of each of these environmental factors to lipid oxidation in oil stored under household conditions is not known. We aimed to identify the major inducer of oxidative deterioration of soybean oil stored at constant (67.0 mL) or increasing (67.0-283 mL) headspace volume, 22 or 32 C, with or without illumination by cold fluorescent light for 56 days by means of fatty acid composition, peroxide value, formation of conjugated dienes, lipid radicals, hexanal, and the decrease in the contents of tocopherols. Soybean oil stored in the dark for 56 days showed an increase of the peroxide value by 124 ± 0.62% (p = 0.006), whereas exposure of the oil to light in a cycle of 12 h light alternating with 12 h darkness for 56 days led to a rise of the peroxide value by 1473 ± 1.79% (p ≤ 0.001). Little effects on the oxidative status of the oil were observed after elevating the temperature from 22 to 32 C and the headspace volume from 67.0 to 283 mL during 56 days of storage. We conclude that storing soybean oil in transparent bottles under household conditions might pose an increased risk for accelerated lipid oxidation induced by exposure to cold fluorescent light.