Red wine won't get sweet. In the process of brewing wine, yeast will eat the sugar in grape juice and metabolize it into alcohol, which becomes the wine we see. With more and more alcohol in grape juice, the sugar is inevitably less and less, thus becoming a dry wine that is not sweet. If we want to sweeten wine, we must call it sweet wine in several ways. The first method is to concentrate sweet substances. In this way, we will naturally freeze grapes, let healthy grapes be infected with mold, air-dry, etc., so that the water in the grapes will be lost, and finally the grape juice with high sweetness will be left for wine making, and finally the wine will be sweet. Ice wine, noble wine, air-dried liqueur and straw wine are all brewed in this way. The second method is to add sweet substances, not sugar, but grape mash to watch the concentrated grape juice. For example, German fresh milk, sweet sherry and so on are all sweet wines brewed in this way. And the simplest and rudest fermentation interruption. In the middle stage of fermentation, the yeast was eliminated by killing yeast or filtering, so that it could not continue to ferment, and sweet wine was obtained. This is how port wine is brewed.