Malolactic Fermentation (also refered to as MLF in tasting notes) - is the winemaking process of a changing sharp, tart-tasting 'malic' acid (like those found in green apples skins), which is naturally present in grape must, and converting them to softer-tasting 'lactic' acid (like that found in milk).
This secondary fermentation is standard practice and applied to most red wines. Though around the world you can more and more white wines benefiting from the process - like Chardonnay made in varied styles. Besides softening acidity in a wine, malolactic fermentation can also impart a buttery or creamy note to a wine. Malolactic fermentation also produces esters in the wine, many of which are responsible for pleasant 'fruit' aromas in wine.

 

The lactic acid bacteria responsible for malolactic fermentation are called (Oenocuccus oeni). This process can occur naturally - through typically during winemaking, malolactic fermentation is initiated by an inoculation of desirable bacteria. This prevents undesirable bacterial strains from producing any unpleasant aromas and flavours. Conversely, some winemakers actively prevent malolactic conversion when it is not desired, to prevent accidental initiation and maintain a fresher, more crisp character in their finished wine.
Sometimes malolactic fermentation can occur unintentionally after the wine is bottled. This is almost always a fault - and the result is a slightly carbonated wine that typically tastes bad and with a little spritz.
Because the process consumes malic acid, which is present at the time the grapes are crushed. Malolactic fermentation can take place at any time during or after alcoholic fermentation. A wine undergoing MLF will be cloudy due to the presence of the bacteria, and may have the curious smell of buttered popcorn.
So a rich, creamy, full-bodied and well rounded Chardonnay, such as the Brookfields 'Marshall Bank' Chardonnay 2015, which many of you have enjoyed previous vintages over the years, is a result of the process of malolactic fermentation.