Effects of clusters exposure levels on pyrazines content in red wines of Vitis vinifera cv. Maturana Tinta de Navarrete

Abstract

Maturana Tinta de Navarrete is a minority grape variety recovered and authorized in Rioja recently. Due its valuable enological proprieties, it is being planted along the entire appellation, but its volatile sensory attributes are highly influenced by methoxypyrazines concentration. The objective is decreasing the pyrazines content in order to avoid vegetal descriptors. Two different training systems (VSP and free cordon) combined with leaf plucking treatments were performed within a commercial vineyard in order to modify bunch exposition levels to the sunlight radiation during 2010 and 2011 years. Three methoxypyrazines were analyzed in grapes and wines both years: 3-isobutyl-2-methoxypyrazine (IBMP), 3-isopropyl-2-methoxypyrazine (IPMP) and 3-sec-butyl-2-methoxypyrazine (SBMP). Leaf plucking and trellis systems involved significant differences in grape and wine IBMP content during the first year: the IBMP concentration decreased 56% in wine, while an increase of 80% in the bunch exposure was determined in the vineyard. The pyrazines content was not modified significantly the second year, but the same tendency of the previous year was observed. Leaf plucking and the training systems are valuable tools in order to modify IBMP concentration, although it is also influenced by seasonal weather conditions.