Elicitors: A strategy to improve phenolic composition in grapes and wines

Abstract

The technological importance of phenolic compounds, especially flavonoids, is well known. They are responsible for the color of wines, especially anthocyanins (colored pigments responsible for the chromatic characteristics of red wines), proanthocyanidins (responsible for the long term stability of red wine color) and flavonols (compounds that may influence wine through copigmentation), and some other organoleptic properties such as astringency, bitterness and body. Another important aspect that has been widely studied in recent years is the role of grape and wine phenolic compounds in the human diet. In this context, different tools have been evaluated in recent years. It has been proved that phenolic biosynthesis may be induced in response to different biotic and abiotic elicitors (Goetz et al., 1999; Song et al., 2015). In this respect, elicitors are molecules able to stimulate plant defense mechanisms which include the activation of secondary biosynthetic pathways such as the one leading to the formation of phenolic compounds (Ferrari, 2010). Our studies have focused on the effect of two elicitors, benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) and methyl jasmonate (MeJ). BTH is a synthetic functional analogue of the plant endogenous hormone-like compound salicylic acid, and MeJ, naturally occurring plant growth regulators that modulate chlorophyll degradation and anthocyanin biosynthesis (Gozzo 2003). The objective of this study was to evaluate the effect of two different elicitor bunch applications to grapevine on the phenolic composition wine, taking account different factors: varieties (Monastrell, Cabernet Sauvignon, Merlot); moment application (veraison, and mid-ripening period) and the use of enological methodology (cold pre-fermentation).