title: Effect of Ethanol, Sulfur Dioxide and Glucose on the Growth of Wine Spoilage Yeasts Using Response Surface Methodology.
abstract: Response surface methodology (RSM) was used to study the effect of three factors, sulfur dioxide, ethanol and glucose, on the growth of wine spoilage yeast species, Zygosaccharomyces bailii, Schizosaccharomyces pombe, Saccharomycodes ludwigii and Saccharomyces cerevisiae. Seventeen central composite rotatable design (CCRD) trials were designed for each test yeast using realistic concentrations of the factors (variables) in premium red wine. Polynomial regression equations were fitted to experimental data points, and the growth inhibitory conditions of these three variables were determined. The overall results showed Sa. ludwigii as the most resistant species growing under high ethanol/free sulfur dioxide concentrations, i.e., 15% (v/v)/20 mg L-1, 14% (v/v)/32 mg L-1 and 12.5% (v/v)/40 mg L-1, whereas other yeasts did not survive under the same levels of ethanol/free sulfur dioxide concentrations. The inhibitory effect of ethanol was primarily observed during longer incubation periods, compared with sulfur dioxide, which showed an immediate effect. In some CCRD trials, Sa. ludwigii and S. cerevisiae showed growth recovery after a short death period under the exposure of 20-32 mg L-1 sulfur dioxide in the presence of 11% (v/v) or more ethanol. However, Sc. pombe and Z. bailii did not show such growth recovery under similar conditions. Up to 10 g L-1 of glucose did not prevent cell death under the sulfur dioxide or ethanol stress. This observation demonstrates that the sugar levels commonly used in wine to sweeten the mouthfeel do not increase wine susceptibility to spoilage yeasts, contrary to the anecdotal evidence.
authors.affiliation: Laboratório de Microbiologia, Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia, University of Lisbon, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Chandra
authors.affiliation: Laboratório de Microbiologia, Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia, University of Lisbon, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
authors.forename: Inês
authors.initials: I
authors.lastname: Oro
authors.affiliation: Centro de Engenharia dos Biossistemas (CEER), Instituto Superior de Agronomia, University of Lisbon, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
authors.forename: Suzana
authors.initials: S
authors.lastname: Ferreira-Dias
authors.affiliation: Laboratório de Microbiologia, Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia, University of Lisbon, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
authors.forename: Manuel
authors.initials: M
authors.lastname: Malfeito-Ferreira
mesh_terms: D000431:Ethanol / Q000378:metabolism / Q000494:pharmacology*; D005163:Factor Analysis, Statistical; D005285:Fermentation; D005516:Food Microbiology; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D050296:Microbial Viability / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D004718:Saccharomycetales / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D012568:Schizosaccharomyces / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D013458:Sulfur Dioxide / Q000378:metabolism / Q000494:pharmacology*; D014920:Wine / Q000032:analysis; D020068:Zygosaccharomyces / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
chemical_list: D013458:Sulfur Dioxide; D000431:Ethanol; D005947:Glucose