Abstract
The application of elicitors, such as methyl jasmonate (MeJ) and benzothiadiazole (BTH), has provided satisfactory results by increasing the polyphenol content of grapevines. However, in the case of some treated grape varieties, it is difficult to extract their phenolic compounds into the wine, because of variations in the components of the skin cell wall (SCW) and the potential effects on some complex carbohydrates (polysaccharides and oligosaccharides). This paper attempts to ascertain whether the individual application of MeJ and BTH at two points of the maturation cycle (veraison and mid-ripening) of Monastrell grapes, influences the content of complex carbohydrates released into wines. The application of elicitors in the vineyard did not affect the concentration of mannoproteins (MPs) (from yeast) in the resulting wine. However, MeJ, BTH and MeJ + BTH treatments (at veraison or mid-ripening) reduced the concentrations of ramnogalacturonans type II (RG-II) and total polysaccharides (TPs) (both from grapes) released into the wine. Results suggest that a reduction of pectic derivatives and/or a reinforcement of SCW occurred as a result of the action of these elicitors, decreasing the release of polysaccharides and oligosaccharides into the wine during maceration. However, sensory analysis found that tasters were not able to distinguish between wines from control and treated grapes. Further years of study are needed, in this and other varieties and locations, to determine the extent of possible cell wall modifications associated with elicitor treatments.