Development and characterization of a pure stilbene extract from grapevine shoots for use as a preservative in wine

Abstract

Grapevine shoots, known to be a source of bioactive stilbenes, are considered one of the most important and abundant waste products from the vineyard. The objective of this study was to obtain a pure stilbene extract from grapevine shoots and test its properties, mainly antimicrobial ones, as a preservative in wine. A new extract with a purity of 99% in stilbenes was obtained by centrifugal partition chromatography. The extract was characterized by HPLC-MS, the main compounds being E-ε-viniferin (70%) and E-resveratrol (18%). The stability conditions for the extract solution were low temperature (4 °C) and darkness for a maximum of 21 days. Data regarding to the stability of E-ϵ-viniferin, ω-viniferin and r-viniferin are reported first.The antimicrobial activity of the extract was higher against yeast (Brettanomyces bruxellensis, Zygosaccharomyces bailli, Haseniaspora uvarum, Candida zemplinina) than against bacteria (Lactobacillus hilgardii, Oenococcus oeni, Pediococcus pentasaceus). The best antimicrobial activity was found on Brettanomyces bruxellensis and Zygossaccharomyces bailli. The aromatic characterization of the extract allows us to establish that it does not affect the sensory properties of wine, and thus wine quality is not compromised with the addition of the extract. All of the above allow us to propose ST99 as a promising alternative to SO2 in wines, including rose and white wines.