A new method for monitoring the extracellular proteolytic activity of wine yeasts during alcoholic fermentation of grape must

Biocatalysis in the winemaking industry: Challenges and opportunities for immobilized enzymes

Enzymes are powerful catalysts already being used in a large number of industrial processes. Impressive advantages in enzyme catalysts improvement have occurred in recent years aiming to improve their performance under harsh operation conditions far away from those of their cellular habitat. Production levels of the winemaking industry have experienced a remarkable increase, and technological innovations have been introduced for increasing the efficiency at different process steps or for improving wine quality, which is a key issue in this industry. Enzymes, such as pectinases and proteases, have been traditionally used, and others, such as glycosidases, have been more recently introduced in the modern wine industry, and many dedicated studies refer to the improvement of enzyme performance under winemaking conditions. Within this framework, a thorough review on the role of enzymes in winemaking is presented, with special emphasis on the use of immobilized enzymes as a significant strategy for catalyst improvement within an industry in which enzymes play important roles that are to be reinforced paralleling innovation.

Combined effect of the Saccharomyces cerevisiae lag phase and the non-Saccharomyces consortium to enhance wine fruitiness and complexity

Non-Saccharomyces (NS) species that are either naturally present in grape must or added in mixed fermentation with S. cerevisiae may impact the wine's chemical composition and sensory properties. NS yeasts are prevailing during prefermentation and early stages of alcoholic fermentation. However, obtaining the correct balance between S. cerevisiae and NS species is still a critical issue: if S. cerevisiae outcompetes the non-Saccharomyces, it may minimize their impact, while conversely if NS take over S. cerevisiae, it may result in stuck or sluggish fermentations. Here, we propose an original strategy to promote the non-Saccharomyces consortium during the prefermentation stage while securing fermentation completion: the use of a long lag phase S. cerevisiae. Various fermentations in a Sauvignon Blanc with near isogenic S. cerevisiae displaying short or long lag phase were compared. Fermentations were performed with or without a consortium of five non-Saccharomyces yeasts (Hanseniaspora uvarum, Candida zemplinina, Metschnikowia spp., Torulaspora delbrueckii, and Pichia kluyveri), mimicking the composition of natural NS community in grape must. The sensorial analysis highlighted the positive impact of the long lag phase on the wine fruitiness and complexity. Surprisingly, the presence of NS modified only marginally the wine composition but significantly impacted the lag phase of S. cerevisiae. The underlying mechanisms are still unclear, but it is the first time that a study suggests that the wine composition can be affected by the lag phase duration per se. Further experiments should address the suitability of the use of long lag phase S. cerevisiae in winemaking.