RESUMO
This detailed study observed the yeasts present in the ecological niche of "wine must". The dynamics and identity of non-Saccharomyces yeasts during the cold maceration and alcoholic fermentation of grape must were investigated under real production conditions in the Bordeaux region. Furthermore, we studied the impact of two oenological parameters on the development and diversity of non-Saccharomyces yeasts during cold maceration: temperature management and the timing of dried yeast addition. The non-Saccharomyces community underwent constant changes throughout cold maceration and alcoholic fermentation. The highly diverse non-Saccharomyces microflora was present at 10(4)-10(5) CFU/mL during cold maceration. The population increased to a maximum of 10(6)-10(7) CFU/mL at the beginning of alcoholic fermentation, then declined again at the end. The population at this point, evaluated at around 10(3)-10(4) CFU/mL, was shown to be dependent on the timing of yeast inoculation. The choice of temperature was the key factor for controlling the total yeast population growth, as well as the species present at the end of cold maceration. Hanseniaspora uvarum was a major species present in 2005 and 2006, while Candida zemplinina was very abundant in 2006. A total of 19 species were isolated.
Assuntos
Manipulação de Alimentos/métodos , Microbiologia Industrial , Polimorfismo de Fragmento de Restrição , Vinho/microbiologia , Leveduras/classificação , Leveduras/crescimento & desenvolvimento , Contagem de Colônia Microbiana , DNA Fúngico/química , DNA Fúngico/genética , Etanol/metabolismo , Fermentação , Cinética , Reação em Cadeia da Polimerase/métodos , Dinâmica Populacional , Crescimento Demográfico , Especificidade da Espécie , Temperatura , Fatores de Tempo , Leveduras/genética , Leveduras/isolamento & purificaçãoRESUMO
Several studies have reported the beneficial influence of non-Saccharomyces yeasts and their potential applications in the wine industry, mainly in mixed-culture fermentation with S. cerevisiae. The potential impact of 15 non-Saccharomyces strains from 7 species on 4-methyl-4-sulfanylpentan-2-one (4MSP) and 3-sulfanylhexan-1-ol (3SH) release in model medium and Sauvignon Blanc must was evaluated after partial fermentation. Whereas the impact of non-Saccharomyces on 4MSP release in both media was low, some M. pulcherrima, T. delbrueckii and K. thermotolerans strains had a high capacity to release 3SH, despite their minimal fermentation activity. As previously demonstrated for Saccharomyces yeast, this contribution is strain dependant. Taking into account their dynamic and quantitative presence during the whole process, the real impact of non-Saccharomyces yeast on 4MSP and 3SH release was evaluated using a recreated community simulating the yeast ecosystem. Our results revealed a positive impact on 3SH release in Sauvignon Blanc wines by promoting non-Saccharomyces yeast activity and delaying the growth of S. cerevisiae. Some non-Saccharomyces yeast strains are capable of making a positive contribution to volatile thiol release in wines, essentially during the pre-fermentation stage in winemaking, when this microbiological sub-population is dominant.