What does malolactic fermentation primarily convert?

Malolactic fermentation primarily converts malic acid to lactic acid. This process is significant in winemaking as it helps to soften the acidity of the wine. Malic acid, which is found in many fruits including grapes, has a tart taste. The conversion to lactic acid results in a smoother mouthfeel and can also add complexity to the wine's flavor profile.

During malolactic fermentation, lactic acid bacteria metabolize the malic acid present in the wine. This transformation not only reduces the sharpness of the wine but can also result in the production of additional compounds that contribute to the wine’s aroma and taste, enhancing its overall quality. This fermentation process is particularly utilized in the production of certain wines like Chardonnay, contributing to the creamy textures and flavors associated with the varietal.

The other options describe different processes that are not related to malolactic fermentation. For instance, glucose to alcohol refers to alcoholic fermentation, which is a separate process where yeast converts sugars into ethanol and carbon dioxide. Sucrose to fructose is a conversion involved in other biochemical processes, and citric acid to acetic acid pertains to different fermentation pathways not typically associated with winemaking.