Alcoholic Fermentation and Maceration

The environmental condition under which fermentation occurs is very different from those of traditional autumnal winemaking, and imposes clear difficulties. The temperature of the must is often about 5 °C, or lower and its high sugar content jointly impede the onset and conduct of fermentation. 

During traditional winemaking in October, endogenous yeasts are very active and their action may need to be limited by appropriate additions of sulfur dioxide. Usually spontaneous fermentation begins with apiculate yeasts of the genus Hanseniaspora. However, their extended 

Alcoholic fermentation usually begins, albeit slowly, by yeast specialized to grow at low temperatures and they metabolize most of the sugars into alcohol. Subsequently, other strains more resistant to the increasing alcohol content prevail and finish the fermentation process. 

The sequence of strains following one another may produce distinctive results, depending on their individual characteristics and on prevailing conditions. Occasionally, these consequences may be undesirable, contributing to off-odor production and inducing color loss by adsorption. This is particularly a problem when fermentations are prolonged. 

In order to better manage winemaking and avoid defects, the use of selected starter yeast strains, suited to specific conditions, are a standard feature of modem in winemaking. These strains belong to the same yeast species usually found in spontaneous Amarone fermentations S. cerevisiae and S. bayanus. 

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