Malolactic fermentation: the temperature factor – Malolactic heating
Wine is the result of a multitude of chemical and bio-chemical reactions, the fundamental processes being alcoholic fermentation and then malolactic fermentation.
Malolactic fermentation, or malolactic conversion, is the phase in which mallic acid is degraded into lactic acid and carbon dioxide through the action of lactic bacteria.
The resulting wine is biologically stable with greater organoleptic complexity, softer and more balanced, more persistent, richer in body (due to the concentration of polysaccharides) and with finer aromas. Malolactic favours tertiary aromas in the wine, which complement the primaries (aromas derived from the vine variety) and secondaries (aromas due to vinification).
Normally, malolactic fermentation is most welcome for red wines, but nowadays it has also been introduced in important white wines with great smoothness.
One can rely on the bacteria naturally present in the must, or one can resort to inoculations of selected bacterial strains belonging to the genera Leuconostoc, Pedicocus, Lactobacillus and Oenococcus.
These bacteria are living organisms, and as such have tolerance thresholds, and outside certain chemical, physical and nutritional limits they do not survive. The generally optimal conditions are:
- TEMPERATURE: between 15 and 25°C;
- PH: optimum acidity is between 3.4 and 4.6;
- ALCOHOL: up to 14% vol. they tolerate it, but if the wine is very alcoholic (and perhaps very acidic at the same time) malolactic fermentation is disadvantaged;
- SULPHUR DIOXIDE: the action of this compound inhibits unwinding, total SO2 should be less than 30 ppm for whites and 50 ppm for reds and free SO2 less than 10 ppm;
- OXYGEN: develops well in its total absence but even if it is present, it is not a limiting factor.
Effect of temperature on malolactic fermentation
Generally speaking, the temperature is considered optimal at around 19°C. Temperatures above 25°C slow down malolactic fermentation and increase undesirable by-products and volatile acidity; below 15°C, bacterial activity is reduced and is almost zero.
If the malolactic process takes place by inoculation, it is important to already have the wine at a temperature of 18-20°C, as bacteria are very sensitive to temperature shocks.
EH-POWERBELT: mobile electric heater for amphorae, barrels and tanks, ideal for heating and controlling the wine or ‘pied de cuve’ during the malolactic phase and beyond
Cofilea has developed specifically for the wine industry the EH-POWERBELT electric heating bands, easy to apply externally to tanks and barrels, without coming into contact with the wine and must, suitable for heating and maintaining temperature in all processing phases requiring heat.
Main features of the EH-POWERBELT heating pads:
- Adjustable and repositionable;
- Flexible and resistant;
- Low consumption and insulation.