The stilbene Σ-viniferin was identified in the hydro-methnolic extracts of grape stems and its highest concentration was in the white varieties ‘Rabigato’ and ‘Viosinho’ (2.99 and 2.61 mg g−1 dw, respectively), being also stressed their content in the red variety ‘Sousão’ (2.48 mg g−1 dw) (Fig. 2E).