Can the water quality influence the chemical composition, sensory properties, and oxidative stability of traditionally extracted argan oil?

Abstract

Argan oil (AO) is an appreciated vegetable oil thanks to its high nutritional and cosmetic values. AO extraction technology has evolved to meet the market demand. However artisanal production is still widely practiced. The present study aimed at highlighting the influence of water quality on the physicochemical and sensory properties of artisanally extracted AO. To meet this objective, AO was prepared using various water types namely: well water (AOWW), tap water (AOTW), mineral water (AOMW), distilled water (AODW), and ultra-pure water (AOUW). The obtained AOs were evaluated in terms of routinely measured quality indices: iodine, peroxide, acid, and anisidine values, UV specific coefficients extinction, refraction index, and moisture content. Chemical composition (fatty acids, sterols content, and tocopherols content) was investigated together with oxidative stability (OS) and sensory properties. As revealed by the statistical test used, water quality impacted significantly mainly on AO chemical composition, OS, and sensory properties. Obtained results of almost studied quality attributes were consistent with the Official Moroccan Norm. The greatest values of saturated and monounsaturated fatty acids were recorded in AOMW and OAWW, respectively, while AOUW together with AOTW displayed the best record of polyunsaturated fatty acids. Moreover, the highest values of tocopherols were found in AOTW and AOUW. AODW and AOUW presented greatest values of sterols content, OS, and shelf life. Likewise, sensory analysis was satisfactory in almost obtained AOs. Principal component analysis confirmed these results and allowed allowed a good separation among AOs especially with sterols and tocopherols. Based on these outcomes, it could be concluded that water quality is an important parameter to consider by AO producers, ultra-pure and distilled water seemed to exert an ameliorative effect on quality, stability, and shelf life of AOs.