Identification of green, aggressive and hard character of wines by a chemo-sensory directed methodology
Abstract
With climate change, it is progressively more often to obtain grapes with an acceptable content in sugars or acids but with immature tannins described as green, aggressive or hard (noted as GAH onwards). During winemaking, the oenologist has to make decisions related to the elaboration of such grapes based mainly on empirical experience, given the lack of objective criteria to this concern. An increase in the chemical and sensory knowledge of immature tannins would allow managing this GAH character of grapes with the maximum possible efficiency during winemaking processes. The present work aims at isolating and identifying the group of compounds responsible for the GAH character present in wines. Thirty-eight wines with a priori different levels of GAH were submitted to sensory analysis by a panel of 25 wine experts. Thirteen attributes and two multidimensional terms (preference and GAH) were rated. Results showed that GAH concept was negatively correlated to preference and positively to aroma (vegetal) and in-mouth terms (astringency). Four wines with different levels of GAH were fractionated by solid-phase extraction and semipreparative liquid chromatography. Six odorless fractions (F1-F6) were isolated for each wine and further submitted to sensory characterization. Results showed that all fractions, except for F3 shared sensory properties for the four wines. F1 and F2 were characterized by attributes such as burning, hot and bitter. F4 and F6 were mainly sweet, watery, silky, fleshy, oily and greasy and F5 dry, coarse and granular. Differently, fraction F3 obtained from wines with high GAH was significantly different from wines with low GAH. Wines with high score for GAH was mainly dry, burning, sour and bitter, while for wines low in GAH was dusty and watery. These results are promising and would suggest that the developed methodology have succeed in isolating the group of compounds potentially involved in the green, aggressive and hard character of wines.
Issue: Macrowine 2016
Type: Poster
Authors
*Universidad de La Rioja