The heating requirements for malolactic fermentation (MLF) in tanks or barrels are based on the heating requirements from the ambient to the fermentation temperature and the conductive losses from the tank to the room. Many variations in temperature and duration exist, however, and are dependent on the winemaker. Malolatic fermentations are dependent upon wine conditions, bacteria activity and temperature. They can occur quickly and easily or may take an extended period. Often in the case of non-heated wine, MLF will also complete in the following spring when ambient temperatures increase. The room temperature in the case of malolactic fermentation in barrels is assumed to be 5°C above the fermentation temperature, optimised at 20°C. An energy input for heating the room and keep it a constant temperature was determined to be 0.067 kWh/l of wine fermented, assuming a period of 56 days for malolactic fermentation [19]. An additional 0.0019 kWh/l of wine fermented was determined for energy use for air circulation for wine fermented in barrels. Karousou et al.’s [17] study calculated that 0.029 kWh of heating is necessary per litre of red wine for malolactic fermentation at 30°C.
Tank pumping, racking, centrifuge and filtration are all common activities in this stage of the winemaking process and have been discussed in “Production”.
