Evaluation of starter cultures for application in Oenology
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2017
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Nos últimos anos, o papel das leveduras não-Saccharomyces na vinificação, previamente diabolizado e negligenciado, tem sido reavaliado tendo sido proposta a sua utilização em fermentações com vista à melhoria e/ou distinção do perfil aromático dos vinhos. Tendo por base estudos prévios, em que se verificou que a estirpe Hanseniaspora guilliermondii UTAD222 altera significativamente o perfil de compostos aromáticos encontrados no final da fermentação quando inoculado em consórcio com S. cerevisiae UCD522, neste estudo foi objetivo aumentar o conhecimento sobre este consórcio. Para isso, foi utilizada a metodologia de superfície de resposta (RSM) associado a um desenho experimental de compósito central (CCD) para avaliar o efeito combinado de diferentes condições de fermentação no crescimento e atividade fermentativa das leveduras bem como na produção de compostos do vinho sensorialmente relevantes. Quatro variáveis independentes, ou seja, temperatura de fermentação (10ºC - 30ºC), concentração de azoto (100-500 mg/L) e de açúcares (150-300 g/L) iniciais e níveis de inóculo de H. guillliermondii (0-1x10⁶ CFU/ml) foram estudados. A análise estatística dos dados experimentais mostrou que, em geral, o azoto foi o principal fator que afetou a cinética de fermentação bem como os metabolitos produzidos, seguido pelos níveis de açúcares e temperatura de fermentação. Mais importante, os efeitos relevantes associados à presença de H. guilliermondii reforçam o interesse na sua aplicação futura em fermentações vínicas conduzidas por culturas mistas.
Over the last years, the role of non-Saccharomyces yeasts in winemaking, previously diabolized and neglected has been re-evaluated, and their use has been proposed in controlled mixed fermentation towards the improvement of wine complexity, aroma profile and control of spoilage microorganisms. Based on previous studies, where the yeast strain Hanseniaspora guilliermondii UTAD222 was found to significantly alter the profile of aroma compounds found at the end of the fermentation when inoculated in consortium with S. cerevisiae UCD522, in this study we aim to increase knowledge on this yeast consortium. For this purpose, Response Surface Methodology (RSM) based on central composite (CCD) was employed to statistically evaluate the combined effect of different conditions, on yeast growth and fermentative activity and on the production of sensory relevant wine compounds. Four independent variables i.e., fermentation temperature (10ºC-30ºC), initial nitrogen (100-500 mg/L) and sugars concentration (150–300 g/L) and inoculum levels of H. guillliermondii (0 – 1x10⁶CFU/ml) were studied. The statistical analysis of the experimental data showed that overall, nitrogen was the main factor impacting fermentation kinetics and metabolites produced, followed by sugars levels and fermentation temperature. More important, the effects seen due to H. guilliermondii presence prompt the future application of this non-Saccharomyces strain in mixed-starter culture wine fermentations.
Over the last years, the role of non-Saccharomyces yeasts in winemaking, previously diabolized and neglected has been re-evaluated, and their use has been proposed in controlled mixed fermentation towards the improvement of wine complexity, aroma profile and control of spoilage microorganisms. Based on previous studies, where the yeast strain Hanseniaspora guilliermondii UTAD222 was found to significantly alter the profile of aroma compounds found at the end of the fermentation when inoculated in consortium with S. cerevisiae UCD522, in this study we aim to increase knowledge on this yeast consortium. For this purpose, Response Surface Methodology (RSM) based on central composite (CCD) was employed to statistically evaluate the combined effect of different conditions, on yeast growth and fermentative activity and on the production of sensory relevant wine compounds. Four independent variables i.e., fermentation temperature (10ºC-30ºC), initial nitrogen (100-500 mg/L) and sugars concentration (150–300 g/L) and inoculum levels of H. guillliermondii (0 – 1x10⁶CFU/ml) were studied. The statistical analysis of the experimental data showed that overall, nitrogen was the main factor impacting fermentation kinetics and metabolites produced, followed by sugars levels and fermentation temperature. More important, the effects seen due to H. guilliermondii presence prompt the future application of this non-Saccharomyces strain in mixed-starter culture wine fermentations.
Descrição
Dissertação de Mestrado em Biotecnologia e Qualidade Alimentar
Palavras-chave
Vinho , Não-Saccharomyces , Cultura mista , Modelo composito central , Metodologia de superfície de resposta