Degradation of Argan Oils Used in Edible and Cosmetic Applications After Exposure to UV Light

Abstract

This study investigates for the first time the effects of UV light exposure on the chemical composition of artisanal and cold-pressed culinary and cosmetic argan oils, as well as their quality and biological activities. We ascertained the oxidative stability of both types of oil through measurements of the peroxide value, acidity, UV-spectrophotometric indexes (E232 and E270), and iodine value. Over the course of eight hours at room temperature, the impact of UV light on the breakdown of tocopherols, polyphenols, chlorophylls, and carotenoid pigments was examined. The findings showed that during photo-oxidation, acidity, peroxide value, and particular extinction coefficients (E₂₃₂ and E₂₇₀) gradually increased. On the other hand, a decline in the content of polyphenols, tocopherols, carotenoid, and chlorophyll was noted. Interestingly, iodine levels failed to improve. Although after an eight-hour degradation, the physicochemical profile of Argan oils remained exceptional. DPPH^• (1,1-Diphenyl-2-picrylhydrazyl) antioxidant activity tests showed a gradual decrease in radical inhibition over time, which was attributed to lower levels of tocopherol and polyphenol. However, roasted oils showed antifungal action against Botrytis cinerea fungus, while Argan vegetable oils showed no activity against Escherichia coli, Microbacterium resistens, Staphylococcus saprophyticus, and Raoultella ornithinolytica, according to antimicrobial assays.