User:Na472/Yeast in winemaking

The process of wine involves huge contributions from yeast. Without yeast, there is no microorganism to initiate the process of fermentation. As yeast consumes the sugars in grape juice, carbon dioxide and ethanol are produced among other byproducts. The first step to making wine is the grape cultivation. Clusters of grapes are either harvested by hand or with large agricultural machines designed specifically to harvest grapes without damaging the clusters or vines. Next the clusters are all added into some form of pulverizer or crusher. The grapes are pressed to a certain amount of pressure depending on the varietal. Red wine is produced in a process of maceration that allows the seeds and skins of the grapes to be absorbed into the juice. Once pulverization or maceration completes, the grape juice is sorted from the remains. Elements that makeup the aroma of the wine such as tannins are absorbed and begin to develop within red wine. Throughout the world one of the most common yeasts Saccharomyces cerevisiae is a desirable model to create alcohol. This microorganism is utilized during the fermentation process of wine. Fermentation is what follows the pulverization stage of wine making and is both the most crucial point in winemaking and  the most time consuming. Sometimes wineries will allow the process to happen naturally with the microbiome that developed on the grapes as they grew. More often however, yeasts like Saccharomyces cerevisiae that have been widely studied are used. This yeast has had its effects on flavor, aroma, and even its impact on overall wine quality studied. S. Cerevisiae can increase sensory factors such as the aroma of wine. As the multiple types of sugars such as glucose, fructose, and sucrose are developed into the end product of wine, the byproducts that the yeast make result in complex aromas. The aromas that develop indirectly impact flavor. A wine that has tropical or floral aromas as a result from the yeast can often appear to have flavors such as pineapple or lavender present when tasted.

Sources:

Yeast diversity and native vigor for flavor phenotypes - ScienceDirect

Improving flavor metabolism of Saccharomyces cerevisiae by mixed culture with Wickerhamomyces anomalus for Chinese Baijiu making - ScienceDirect

Effects of co‐fermentation with Candida stellata and Saccharomyces cerevisiae on the aroma and composition of Chardonnay wine - SODEN - 2000 - Australian Journal of Grape and Wine Research - Wiley Online Library

Wine flavor and aroma | Journal of Industrial Microbiology and Biotechnology | Oxford Academic (oup.com)

Genetics of Yeast Impacting Wine Quality | Annual Review of Food Science and Technology (annualreviews.org)

Yeast selection for wine flavor modulation - ScienceDirect