Estresse, comportamento das leveduras durante a segunda fermentação e diferenças entre os métodos Tradicional e Charmat na elaboração de espumantes

Abstract

Studies on the processes involved in the production of sparkling wines can contribute to the advancement of scientific knowledge in oenology and biotechnology. In this biotechnological context, the yeast Saccharomyces cerevisiae plays an important role. The central theme of this thesis is the production of sparkling wines through two fermentations and the behaviour of yeasts during this process. The work is divided into three chapters and six appendices, in which we present the studies conducted during the Doctoral course in Biotechnology. In Chapter 1,tests were conducted in different fermentation environments, with and without the presence ofethanol and SO2, simulating a second fermentation for sparkling wine production. Wedemonstrated that the stress caused by the interaction between SO2 and ethanol present in thebase wine considerably reduces the viability of yeasts at the beginning of this process, whichcan be considered the main yeast inhibitor in this stage. In Chapter 2, we compared theTraditional and Charmat methods of sparkling wine production. We showed that the continuoushomogenization of the wine after the completion of the second fermentation, during the agingof sparkling wines using the Charmat method, triggers the autophagic processes of yeasts,accelerating cellular death compared to the Traditional method, in which yeasts age together at the bottom of the bottle. In Chapter 3, through chemical and sensory analyses, we demonstratedthat sparkling wines produced by the Traditional and Charmat methods, using the same basewine, inoculum, and aging time, exhibit very similar olfactory and gustatory characteristics. Weconcluded that the method itself does not determi ne the quality of the products. In theappendices, a work presented at an event, two publications of technical articles related toChapter 1, and three abstracts submitted to conferences are presented in chronological order.These address studies on the aromatic modelli ng of sparkling wines using different yeast strains,nutrient types, and the aromatic characterization of sparkling wines made from disease-resistantgrape varieties. The results obtained in this thesis and the conclusions drawn can contribute tothe advancement of knowledge in sparkling wine production and indirectly assist in thedevelopment of national vitiviniculture. [resumo fornecido pelo autor]