You can drink it, my father is every fall to make their own wine, the color of their own wine is not as red as the wine sold, but it is a healthy wine without any additives Oh. Add how much according to how much alcohol content you want to make wine, as well as the sugar content of your grapes to determine: usually 17 grams / liter of sugar can be converted into 1 degree of alcohol, then we want to make a degree of 12 dry red wine, we must ensure that 1 liter of grape juice contains 17 * 12 = 204 grams of sugar, if we first measure the sugar content of the grapes themselves is only 180 grams / liter, so that 1 liter of grape juice on the Need to add an additional 204-180 = 24 grams of sugar into, if we have 10 liters of grape juice to be fermented, then the total **** need to add sugar: 10 * 24 grams = 240 grams. The average homebrewer will add more sugar than I calculated because they like sweet wines, but sweet wines have always been something I don't recommend because they are not healthy and don't keep well. Sugar is added all at once at the beginning of fermentation. Sugar is added by taking a portion of the grape juice to dissolve the sugar completely before adding it.