Techniques to achieve moderate alcohol levels in South African wine

The alcohol content of unfortified wines is increasing worldwide. Statistics from three winemaking regions are presented to demonstrate this trend. Some commentators have suggested that the stylistic change has been overdone, and that winemakers now need to seriously consider limiting and even reducing alcohol levels in wine. A basic mathematical model is presented for how yeasts convert sugar in grapes into alcohol. This model is compared with published linear approximations and practical experience. The trend to higher alcohols and growing criticism of high alcohol wines raise the question of how to achieve moderate alcohol levels. Techniques can be employed to achieve moderate alcohols during establishment of a vineyard as well as subsequent viticultural practices. These include choice of vineyard site, decisions during its establishment, canopy management, limiting bunch thinning and bud removal, virus infection, water management, dealing with methoxypyrazines, and harvest timing. Further options are available in the winery to obtain moderate alcohol levels. Application of glucose oxidase enzyme, membrane treatments applied to the must and addition of water can be considered before fermentation. For fermentation, choice of yeasts, temperature, evaporative losses, and residual sugar can play a role. After fermentation, removal of alcohol and barrel maturation can both be used. Although winemaking interventions are possible to reduce alcohol levels and even to cure excessive alcohol, viticultural intervention is likely to be more important overall.