This is a question often asked by many friends who are new to home-brew wine. Should sugar be added to home-brew wine? How much sugar? Making wine from grapes is a biochemical change process. Its principle of change is: the fructose and wine in the grapes turn into alcohol and carbon dioxide under the action of Saccharomyces cerevisiae. The alcohol dissolves in the grape liquid and turns into wine and carbon dioxide. The gas was released into the air. The rough calculation method for converting various sugars into alcohol is: every 17 grams of sugar in 1 liter of wine can convert 1 degree of alcohol. If you want to brew wine with more than 10 degrees, the raw materials of each liter of wine must contain 170 degrees. grams of fructose and glucose. The sugar content in grapes is related to the variety and maturity of the grapes. The better the grape variety, the higher the sugar content; the higher the maturity of the grapes, the higher the sugar content. Generally, the sugar content of wine grapes is higher than that of table grapes. The amount of sugar is much higher. If grapes with very low sugar content are used to make wine, the primary fermentation of the grapes (primary fermentation is also called alcoholic fermentation) will not be easy to start. If the grapes are not fermented well, the wine during the fermentation process will be easily contaminated by other harmful bacteria. If attacked, the wine will easily go bad. Therefore, when using grapes with low sugar content to make wine, sugar must be added. For those who are new to making their own wine, you can add more sugar when starting to make wine. The ratio of 3 pounds of grapes to 1 pound of sugar is actually not too much, because grapes with too much sugar are easy to ferment and become wine. As your winemaking experience continues to increase, the amount of added sugar can be gradually reduced. After all, no matter how good the added sugar is, it is not as good as the fructose and glucose of the grape itself, and adding too much sugar will also affect the aroma and taste of the wine.