The present study was aimed at determining the effect of glucose, ethanol and sulphur dioxide on the growth and volatile phenol production by Brettanomyces bruxellensis in red wines using a response surface methodology approach. Sulphur dioxide proved to have a significant (p < 0.05) negative linear and quadratic effect on growth and 4-ethylphenol production. Concentrations of sulphur dioxide higher than 20 mg L(-1), at pH 3.50, induced immediate loss of cell culturability under growth permissive levels of ethanol. Under high ethanol concentrations (14% v/v), the lag phase increased from 3 to 10 days, growth being fully arrested at 15% (v/v). Glucose up to 10 g L(-1) was found to be a significant factor (quadratic level) in biomass increase under low ethanol (<12.5% v/v) and low sulphite concentrations. However, when cells were inactivated by sulphur dioxide and ethanol, glucose (up to 10 g L(-1)) did not prevent cell death. Production of more than 50 μg L(-1) day(-1) of 4-ethylphenol was only observed in the presence of high numbers (10(6) CFU mL(-1)) of culturable cells, being stimulated by increasing glucose concentrations.
Keywords: 4-Ethylphenol; Brettanomyces bruxellensis; Response Surface Methodology; Spoilage yeasts; Wine.
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