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Sparkling wine yeasts performance: integrated characterization during second fermentation

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Resumo:Sparkling wines are a distingué type of wine, very appreciated worldwide and with an important market value. Their production is based on a second alcoholic fermentation of a base wine. Invariably, Saccharomyces cerevisiae is chosen by wine-makers to perform such fermentation due to its unmatched qualities. Second fermentation process is associated to particular stress factors with which yeasts must cope. Ethanol presence (8-14%), temperatures below 16ºC or nitrogen starvation are among unfavorable conditions yeast must support and that ultimately can compromise the fermentation, delivering an unsatisfactory final product. The objective of this work was to study encapsulated sparkling wine yeasts’ physiological, cytological and molecular adaptation during an in-bottle process of second fermentation at very low temperatures and different concentrations of assimilable nitrogen. Two yeast strains were inoculated in conventional sparkling wine bottles at two different temperatures (10ºC and 12ºC) with two different assimilable nitrogen concentrations (100 mg/l and 56 mg/l), generating 8 fermentation conditions that mimic an actual industrial sparkling wine production. In order to study the physiological changes along the process an integrative and multiparametic characterization was made at specific time-points. For the purpose several yeast parameters were monitored: fermentation kinetics, viability, vitality, glycogen, trehalose, neutral lipids, glutathione, fatty acids, total proteins, ATP, relative expression of targeted stress genes and sensorial properties. Lower temperatures and low nitrogen showed to have a major impact on fermentation, with an influence on evaluated parameters and wine sensorial quality that was highly strain dependent. Strain SC1 was more robust, resilient and well-adapted to 10ºC fermentations, whereas strain SC2 revealed to be more active and plastic, producing higher quality wines at 12ºC. With the information gathered in this work, profitable adjustments in yeast production process are certainly expected, as well as design of new plans of study encompassing different strains and/or additional parameters.
Autores principais:Ferreira, David José Moreira, 1988-
Assunto:Saccharomyces cerevisiae Fermentação Vinho Teses de mestrado - 2013
Ano:2013
País:Portugal
Tipo de documento:dissertação de mestrado
Tipo de acesso:acesso restrito
Instituição associada:Universidade de Lisboa
Idioma:inglês
Origem:Repositório da Universidade de Lisboa

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