Study of the Traditional Argan Oil Oxidation under Different Storage Conditions

Abstract

The autoxidation of argan oil extracted traditionally was followed during a long-term storage, using plastic bottles in presence of air, under nitrogen atmosphere or at 4 °C, in comparison with transparent glass bottles. The autoxidation was evaluated by the simultaneous monitoring of four parameters for a period of 18 months: tocopherols content, oleic and linoleic acids, conjugated dienes and peroxide value.The results showed that the storage in plastic bottles in the light at room temperature, delayed the oxidative degradation of the oil relatively to the transparent glass. This degradation was mitigated by the presence of nitrogen. The maximum content of hydroperoxides, resulting from the degradation of unsaturated fatty acids, was reached after 306 days in the presence of air and 321 days in the presence of nitrogen in the plastic bottles. This effect was recorded only after 273 days in the glass vials. Conjugated dienes changed in the same way as hydroperoxides. The degradation of unsaturated fatty acids taked place after the destruction of tocopherols including ?-tocopherol, which was the major form in the argan oil. The shelf life of the oil was longer (over 18 months) when plastic bottles were placed at 4 °C. The results showed that argan oil extracted traditionally had high stability against the oxidation due to its richness in tocopherols which are powerful antioxidants.

Keywords: Argan oil, glass, nitrogen, oxidation, plastic, storage, temperature