Moscatel vine-shoot extracts as grapevine biostimulant to increase the varietal aroma of Airén wines

Abstract

There is a growing interest in the exploitation of vine-shoots waste, since they are often left or burned. Sánchez-Gómez et al. [1] have shown that vines-shoots aqueous extracts have significant contents of bioactive compounds, among which several polyphenols and volatiles are highlighted. Recent studied had demonstrated that the chemical composition of vine-shoots is enhanced when vine-shoots are toasted [2,3]. The application of vegetable products in the vineyards has led to significant changes towards a more “Sustainable Viticulture”. An innovative foliar application for Airén vine-shoot extracts have been carried out to the vineyard. It has been shown that they act as grape biostimulants, improving certain wine quality characteristics [4]. The aim of this study was to determine the effect of Moscatel aqueous vine-shoots extracts (non-toasted and toasted) on wine quality when they were foliarly applied to Airén grapevines variety, with special attention on varietal volatile compounds to see if this aromatic variety can transmitted its appreciate volatile profile. Two vine-shoots aqueous extracts from Moscatel variety (non-toasted, MVS; and toasted, MVSToasted) were obtained. Previous extraction procedure [1], the toasted sample was submitted to 180ºC during 45 min [2]. After their formulation they were applied to the leaves of Airén grapevines at veraison. Grapes resulted from each treatment were processed following the classical winemaking method for white wines. The detailed analysis of the wine volatile composition was performed by SBSE-GC/MS [1,5]. Airén wines obtained from two treatments, had significantly lower alcohol degree in relation to control wines, which it could be considered an interesting alternative for wine industry as wines with low alcoholic degree are required by consumers. About their volatile profile, both presented a higher aromatic complexity, due to an increase in the varietal volatiles content, along with those considered as wood volatiles.

References: [1] Sánchez-Gómez, R., Zalacain, A., Alonso, G.L., Salinas, M.R. Vine-shoot waste aqueous extracts for re-use in agriculture obtained by different extraction techniques: Phenolic, volatile, and mineral compounds. J. Agric. Food Chem. 2014, 62, 10861–10872. [2] Sánchez-Gómez, R., Zalacain, A., Alonso G.L., Salinas, M.R. Effect of vine-shoots toasting on the generation of high added value volatiles. Flavour Frag J. 2016. In press. [3] Sánchez-Gómez, R., Zalacain, A., Lorenzo, C., Alonso G.L., Salinas, M.R. Effect of toasting intensity on Airén and Moscatel vine-shoots low molecular weight phenolic compounds. Food Chem. 2016. Accepted. [4] Sánchez-Gómez, R., Zalacain, A., Alonso G.L., Salinas, M.R. Vine-shoots and grapevines feedback: Impact on wine quality. Submitted. [5] Pardo-García, A.I., De La Hoz, K.S., Zalacain, A., Alonso, G.L., Salinas, M.R. Effect of vine foliar treatments on the varietal aroma of Monastrell wines. Food Chem. 2014, 163, 258-266.