• aroma;
  • β-glucosidase;
  • Sporidiobolus pararoseus;
  • wine;
  • yeast

Abstract:  For the first time, the production of an extracellular β-glucosidase (Sp-β-gl) by a Sporidiobolus pararoseus yeast strain is reported. The Sp-β-gl activity was quantified, characterized, and assessed for its efficiency in releasing aroma-enhancing compounds in wines. The maximum enzymatic synthesis was after 72 h of growth in a complex media with 20 g/L of cellobiose. The optimal pH and temperature were 5.5 and at 50 °C, respectively. It showed a wide range of pH stability and exhibited quite high thermostability at low temperatures. In addition, this β-glucosidase revealed tolerance to wine-associated inhibitory compounds (sugars and ethanol), showing suitable characteristics for all the stages of alcoholic fermentation. The hydrolysis of the glycosidic terpenes by Sp-β-gl was studied by gas chromatography, and its ability to efficiently release free terpenols has been demonstrated. The concentrations of geraniol, linalool, α-terpineol, and nerol were significantly increased in treated wines. These results suggest the potential application of this new yeast β-glucosidase as an aroma-enhancing enzyme in winemaking.

Practical Application:  The search for new β-glucosidase from yeast sources is important to improve the quality of wines. In this work, an S. pararoseus yeast strain has shown to be capable to produce a β-glucosidase with suitable combination of properties for functionality in wines and with potential to increase the concentration of free aroma compounds, showing good prospects for an industrial application.