Impact of volatile phenols and their precursors on wine quality and control measures of Brettanomyces/Dekkera yeasts

Volatile phenols are aromatic compounds and one of the key molecules responsible for olfactory defects in wine. The yeast genus Brettanomyces is the only major microorganism that has the ability to covert hydroxycinnamic acids into important levels of these compounds, especially 4-ethylphenol and 4-ethylguaiacol, in red wine. When 4-ethylphenols reach concentrations greater than the sensory threshold, all wine’s organoleptic characteristics might be influenced or damaged. The aim of this literature review is to provide a better understanding of the physicochemical, biochemical, and metabolic factors that are related to the levels of p-coumaric acid and volatile phenols in wine. Then, this work summarizes the different methods used for controlling the presence of Brettanomyces in wine and the production of ethylphenols

Characterization of the beta-glucosidase activity produced by enological strains of non-saccharomyces yeasts

The beta-glucosidase activities of 20 wine-related non-Saccharomyces yeasts were quantified, characterized,and assessed for their efficiency in releasing aroma-enhancing compounds during the winemaking process. Of these enzymatic activities, the beta-glucosidase activity of Debaryomyces pseudopolymorphus revealed the most suitable combination of properties in terms of functionality at wine pH, resistance to wine-associated inhibitory compounds (glucose, ethanol, and sulfur dioxide), high substrate affinity, and large aglycone-substrate recognition. Its potential as a wine aroma–enhancing enzyme was confirmed by the significantly increasing concentrations of free volatiles (citronellol, nerol, and geraniol) during the fermentation of Chardonnay juice inoculated with both D. pseudopolymorphus and a widely used commercial starter culture strain of Saccharomyces cerevisiae, VIN13.R.R. Cordero Otero, J.F. Ubeda Iranzo, A.I. Briones-Perez, N. Potgieter, M.A. Villena, I.S. Pretorius, and P. van Rensbur