Characterisation of Mediterranean grape pomace seed and skin extracts: polyphenolic content and antioxidant activity

Isabelle Ky (1) , Pierre Louis Teissedre (1)

1 OENO - Unité de Recherche Oenologie [Villenave d'Ornon]

Grape pomace seeds and skins from different Mediterranean varieties (Grenache [GRE], Syrah [SYR], Carignan [CAR], Mourvèdre [MOU] and Alicante [ALI]) were extracted using water and water/ethanol 70% in order to develop edible extracts (an aqueous extract [EAQ] and a 70% hydro-alcoholic extract [EA70]) for potential use in nutraceutical or cosmetic formulations. In this study, global content (total polyphenols, total anthocyanins and total tannins), flavan-3-ols and anthocyanins were assessed using HPLC-UV-Fluo-MSn. In addition, extract potential was evaluated by four different assays: Oxygen Radical Absorbance Capacity (ORAC), Ferric Reducing Antioxidant Potential assay (FRAP), Trolox equivalent antioxidant capacity (TEAC) or ABTS assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. As expected, seed pomace extracts contained higher amounts of polyphenols then skin pomace extracts. Indeed, seeds from Syrah contained a particularly important amount of total polyphenols and tannins in both type of extract (up to 215.84 ± 1.47 mg of gallic acid equivalent [GAE]/g dry weight (DW) and 455.42 ± 1.84 mg/g DW, respectively). These extracts also expressed the highest antioxidant potential with every test. For skins, the maximum total phenolic was found in Alicante EAQ (196.71 ± 0.37 mg GAE/g DW) and in Syrah EA70 (224.92 ± 0.18 mg GAE/g DW). Results obtained in this article constitute a useful tool for the pre-selection of grape pomace seed and skin extracts for nutraceutical purposes.

Mots clés: Mediterranean varieties; phenolic compounds; anthocyanins; antioxidant activity

Mots clés: grape pomaces; flavan-3-ols

Domaines: Ingénierie des aliments; Génie des procédés

Isabelle Ky, Pierre Louis Teissedre. Characterisation of Mediterranean grape pomace seed and skin extracts: polyphenolic content and antioxidant activity. Molecules, 2015, 20 (2), pp.2190-2207. ⟨10.3390/molecules20022190⟩. ⟨hal-02639426⟩