Variabilidade do perfil aromático de vinhos Gewürztraminer em função da levedura utilizada na fermentação alcoólica

Abstract

Wine is a complex matrix, the result of numerous biochemical reactions, some of which result in the formation of volatile compounds with sensory impact. One of the metabolic pathways involved in the formation of volatile compounds in wines is the secondary metabolism of yeasts responsible for the alcoholic fermentation process. Traditionally yeasts of the Saccharomyces genus are used in the fermentation of wines and other beverages, however, several studies indicate that the use of yeasts of different genres, commonly cited as non-Saccharomyces, have different enzymatic activities, capable of contributing to the aromatic complexity of wines. One of the grapes rich in precursor compounds present in glycosylated form is cv. Gewürztraminer, characterized by the high concentration of low molecular weight terpenes. This work aimed to evaluate the potential of the variability of the aromatic profile of Gewürztraminer wine, through the analysis of volatile compounds and sensory analysis of Gewürztraminer wines fermented with yeasts of the genera Saccharomyces and non-Saccharomyces. The grapes from the Campanha Gaúcha - RS (Brazil) were done in 14 liters glass containers with three Saccharomyces and two non-Saccharomyces yeasts. After the alcoholic fermentation was completed, classic physical-chemical analyzes were carried out so that the fermentation process was conducted properly. Nine months after the completion of alcoholic fermentation, volatile compounds were analyzed by Gas Chromatography coupled to Mass Spectrometry (GC-MS) and sensory analysis by Quantitative Descriptive Analysis (QDA) test. From the classic oenological analyzes it was found that the yeast Torulaspora delbrueckii had less fermentative power, with less final alcohol content and higher residual sugar and higher acetic acid production, although still below the perception threshold. From the analysis of volatiles, 36 compounds were characterized, including alcohols, esters, terpenoids, ketones, aldehydes, acids, benzenes and volatile phenols. The yeast Saccharomyces cerevisiae bayanus showed greater intensity for most peaks of higher alcohols and esters. In the sensory evaluation, the notes on the aroma attributes of citrus fruits, flora, tropical fruits, and white fruits were higher for Saccharomyces yeasts (T1 and T3) and lower for non - Saccharomyces yeasts (T4 and T5) with the exception of the vegetable attribute, in which the yeast Torulaspora delbrueckii (T4) presented a similar note to Saccharomyces cerevisiae bayanus (T3). In the principal component analysis (PCA) including sensory analysis and volatile compounds analysis it was possible to observe that: 1) the yeast Torulaspora delbrueckii (T4) is opposite to the yeast Saccharomyces cerevisiae cerevisiae (T1) 2) the yeast Metschnikowia pulcherrima (T5) is opposite to the yeast Saccharomyces cerevisiae bayanus (T3) and 3) the yeast Saccharomyces cerevisiae cerevisiae (T2) is closer to all the others. In conclusion is possible affirm that the yeast Saccharomyces cerevisiae bayanus (T3) showed best performance in the production of Gewürztraminer wines, whit more concentration of important volatile compounds as alcohols, terpens and esters, and more height notes in the sensory analysis.