Malolactic fermentation
Malolactic fermentation – I’ve heard of that but what is it?
This fancy sounding process may have a complex name but it is very easy to understand in principle although it takes expertise to get it just right.
This is the process where the acid in wine is converted from malic (which is like the sharp acid in unripe green apples) to lactic (which is creamy and commonly found in milk). It has a major effect on wines such as Chardonnay where a creamy texture is required, but is undesirable in crisp wines such as Aligote or Muscadet. It is also a natural partner to wines that are aged in oak so the majority of red wines have some degree of malolactic fermentation included in the winemaking process.
A strain of malolactic bacteria is added to the wine after the initial fermentation. The direct side effect of this process is for carbon dioxide to be released from the liquid so small bubbles are produced. An inevitable pitfall here is to seal the bottle with a capsule or cork before the malolactic fermentation has finished – the result is that carbon dioxide continues to be released after the wine is packaged and so when it is consumed a small hint of fizz may be detectable. Very occasionally a bottle can be genuinely sparkling although this is rare. If you find some fizz in your wine this is caused by what is known as secondary fermentation. Something very similar to this happens in the wine-making process of Champagne, but this involves a somewhat different technique (which we’ll leave for another time!).
In the hands of a skilled winemaker malolactic fermentation is a crucial technique used to attain the right balance of fruit, texture and flavour. Often the winemaker will only let certain batches of their wines undergo the process, and then blend these with wines which are free of the secondary fermentation. In this way the initial zest and fruit burst of the unprocessed wine marries with the richer textures and other characteristics of the malolactic batch to make a complete wine.