FOLIAR APPLICATION OF METHYL JASMONATE AND METHYL JASMONATE PLUSUREA: INFLUENCE ON PHENOLIC, AROMATIC AND NITROGEN COMPOSITION OFTEMPRANILLO WINES

Abstract

Phenolic, volatile and nitrogen compounds are key to wine quality. On one hand, phenolic compounds are related to wine color, mouthfeel properties, ageing potential. and are associated with beneficial health properties. On the other hand, wine aroma is influenced by hundreds of volatile compounds. Fermentative aromas represent, quantitatively, the wine aroma, and among these volatile compounds, esters, higher alcohols and acids are mainly responsible for the fermentation bouquet. Finally, nitrogen compounds affect the development of alcoholic fermentation and the formation of flavour metabolites. Different approaches have been studied to improve the wine quality. Foliar application of elicitors and nitrogen compounds to vineyard has been studied to palliate the effects of climate change in grape composition, and therefore, to enhance grape and wine quality. Methyl jasmonate (MeJ) is an elicitor able to trigger a response of defense in plants, that induces the production of secondary metabolites. Urea is a nitrogen fertilizer widespread employed due to its small molecular size, higher water solubility, and low cost. MeJ and urea (Ur) have been studied separately as a foliar application in vines. Describing an en-hance of volatile, phenolic and nitrogen compounds in grapes, although their effect in wines sometimes is less evident. In this trial, three treatments were carried out as foliar application: Control, MeJ and MeJ+Ur, during two growing seasons (2019 and 2020) in Tempranillo vineyard. The analysis of phenolic and nitrogen compounds were carried out by HPLC-DAD [1, 2]. Volatile compounds were determined by SPME-GC-MS [3]. The effect of foliar treatments was season dependent. In 2019, MeJ and MeJ+Ur wines were characterized by a higher content of total acylated anthocyanins, but a lower content of total esters, alcohols and acids than control wines. MeJ+Ur wines presented a higher total amino acids content than control and MeJ wines. However, in 2020, MeJ+Ur treatment increased the total content of flavonols, flavanols, hydroxycinnamic acids, stilbenes and total amino acids when compared with control. MeJ wines presented a low content of esters and acids, whereas MeJ+Ur did not show differences with control. Overall, the synergic effect of MeJ+Ur foliar treatment was greater than the effect of MeJ application in order to improve the wine chemical composition.