Comparative study on yields and quality parameters of argan oils extracted by conventional and green extraction techniques

Argan oil is most frequently sold as pure oil, which can be directly applied topically due to its cosmetological proprieties or ingested in order to provide several health benefits. It's also commonly mixed into a number of cosmetic products like shampoos, soaps and conditioners. In this study we aimed to improve the argan oil extraction yield and quality parameters by comparing the effects of different extraction technologies. Argan kernel oils were extracted using four methods: mechanical cold press, Soxhlet extraction with n-hexane, supercritical fluid extraction (SFE), and enzyme assisted extraction with three different enzyme solutions cellulase (cellulast), pectinase (Pectinex) and a mixture of carbohydrase enzymes (Viscozyme®). The quality parameters was evaluated by determining the acid, peroxide and iodine values as well as the extinction coefficients K₂₃₂ and K₂₇₀ as measures of conjugated dienes and trienes, respectively. The results showed that the highest yield (66.37% ± 3.3%) was obtained by enzyme assisted extraction using the carbohydrases enzymes mixture (Viscozyme®), followed by Soxhlet extraction (59.5% ± 3.1%) and pectinase extraction (52.03% ± 3.55%). All argan oils samples obtained by the different methods showed a good oxidation stability, with acid, peroxide and iodine values lower than 0.8 mg/g, 15 meq/kg and 110 g/100 g according to the official argan oil norm, respectively. The results of argan oils quality parameters demonstrated that the enzyme extracted argan oils showed low oxidation, with the following quality parameters: acid values (0.4–0.6 mg/g), iodine values (95–100 g/100 g), dienes (K₂₃₂ < 2), trienes (K₂₇₀ < 0.35), and peroxide values (<1.5 meq/kg). The results proved that the enzyme assisted extraction method can be applied to improve the argan oil yield without affecting the oil quality. The enzyme extraction method may be a great alternative to solvent and cold press extractions for this eco-friendly processing approach.