Occurrence of Brettanomyces/Dekkera in Brazilian red wines and its correlation with ethylphenols

Abstract

The yeast Brettanomyces/Dekkera can cause important spoilage in wines, with the production of ethylphenols and other off-flavor compounds. This study aimed at determining the presence of this yeast and the ethylphenols produced by them in Brazilian red wines, establishing their relationship with other chemical characteristics. Isolates of Brettanomyces/Dekkera were quantified by plating 126 samples of dry red wine in selective culture medium, while ethylphenols were analyzed by solid phase extraction and GC/FID. Free and total SO2, alcohol, total dry extract, residual sugar, total and volatile acidity, and pH were also determined. Brettanomyces/Dekkera was present in 27% of samples. Ethylphenols were detected in most samples, with amounts higher than the threshold limit of 426 g/L found in 46.03% of samples. The majority of wine samples showed inadequate levels of SO2 and residual sugars, facts that might facilitate microbial spoilage. The passage in barrels and the grape varieties (Cabernet Sauvignon and Merlot), did not show any influence on the levels of contamination or ethylphenols contents. The prevalence of Brettanomyces/Dekkera and the concentrations of ethylphenols were high considering the sensory impact they can cause. The growth of Brettanomyces/Dekkera was dependent on the levels of SO2 and alcohol of wines. Knowledge of the contamination, the presence of ethylphenols, and their relationship with the chemical characteristics of wines can entice effective measures to prevent Brettanomyces/Dekkera and contribute to improve the general quality of Brazilian red wines.