The importance of yeast in wine making Yeast is a unicellular microorganism belonging to the fungi kingdom. It is one of the most important ingredients in the wine making process as it is responsible for the fermentation of grape juice into wine. The fermentation process is essential to the production of wine as it convertsthe sugars in grape juice into alcohol. Without yeast, this process would not occur and wine would not be able to … Continue reading making wine from grapes