Evaluation of the phenolic content of virgin grape seed oils from different origins

Virgin grapeseed oil is one of the few vegetal oils, in addition to olive oil, that can be used as raw condiment in food. It is widely produced in countries with a developed wine industry, and particularly in South America countries. However, despite the numerous studies regarding the fatty acids composition of grapeseed oils, only few investigations have been targeted to elucidate their quali-quantitative phenolic profile. One of these works pointed out the presence of vanillic acid and sinapic acid in virgin cold pressed oil from grapeseed [1]. Since in many countries this oils are used as such, without refining processes, that strongly reduce the content of minor compounds, aim of this work was to contribute to highlight the composition of the secondary polar metabolites of this edible oil obtained by a waste-matrix naturally rich in antioxidant phenols. Virgin grapeseed oils with a different provenance have been included in this work. After a liquid/liquid extraction, the obtained phenolic fractions were analyzed by HPLC/DAD/ESI-MS. From the qualitative point of view, any significant difference between the samples was highlighted, excepted for some minor phenols. Over all up to 19 different phenols were identified, belonging to different classes among which, lignans as pinoresinol, several cinnamic acids and derivatives (p-cumaric acid ethyl ester, p-methoxycinnamic acid and chlorogenic acid), and flavonoids such as kaempferol. All these molecules were identified according to their retention times, UV spectra and fragmentation pattern from MS2 experiments. The contribute to the oil stability of these minor phenols could be better evaluated in future studies on grapeseed oils.