The more formal name for table sugar is sucrose. We don’t often think of making sugar as part of the winemaking process, but you can speed up fermentation and reduce the chance of crystallization by converting sucrose into its two components, glucose and fructose, before adding it to the wine must. Inverting sugar speeds up fermentation because it is the glucose and fructose molecules that the wine yeast will eventually convert to the alcohol and carbon dioxide produced in the fermentation process.

Commercial invert sugar is made with an enzyme called invertase. You can buy commercially produced invert sugar at brewing and winemaking supply houses, but it is considerably more expensive than grocery store table sugar. Partially inverted sugar can be made at home from regular table sugar without enzymes. The invert sugar recipe below uses lemon juice, but you can substitute citric acid, ascorbic acid, or cream of tartar, depending on what you have on hand at the time.

Invert sugar is made by mixing two parts table sugar with one part water and adding two teaspoons of lemon juice per pound of sugar. The mixture is brought almost to a boil and then reduced to a vigorous simmer for about 30 minutes. There should be no residual acidity from the lemon juice at this point. Pour the invert sugar syrup into an airtight jar and refrigerate until chilled. You can make a large batch and use it for multiple winemaking sessions.

Invert sugar is used only for fermentation. Don’t use invert sugar to sweeten a finished wine, as it can restart fermentation. Unless you’re making champagne, bottle fermentation rarely has a good result.