Tech talk: isn’t malolactic just sour milk…or grapes?

One of the goals for our blog is to share some of the technical “mysteries” of the wine world. In reality, there are very few real secrets, wine making and marketing has a system like everything else but because it is such a widely discussed but poorly understood subject, everyone assumes that there are some special tricks. We like to do our bit to help the understanding and pleasure of enjoying fine wine.

So, to fill a gap in the news, I thought that we would briefly share at least what we know about malolactic fermentation. What, I hear – do I have to drink this stuff? Isn’t lactic acid what you find in sour milk products? Well yes that too!! In fact lactic acid is commonly found in many natural food products as it plays a key role in biochemical processes.

Grape juice is more than just fruit juice and sugar. Grape juice must (that is crushed grape juice skins, acids, sugar, bacteria, etc) contains malic acid, which remains in the wine after the main primary fermentation. Malic acid is quite a tart tasting acid which is very beneficial in sharp tasting refreshing dry white wines such as Sauvignon Blanc. With red wines where one wants a fuller, richer and rounder taste, malic acid is less desirable. Happily nature has a very elegant solution for us, called malolactic fermentation which produces softer lactic acid.

This secondary fermentation process generally occurs naturally at specific temperatures using lactic acid bacteria (extracted from the grape skins during winemaking). These bacteria consume the malic acids, converting them to lactic acid and liberating a small amount of Carbon Dioxide – hence fermentation. This reaction process only happens typically above 19 or 20 degrees Celsius. This means that in some cases, if the temperature in a cellar during late autumn or winter is cool, the wine will wait until the warmer spring time before starting the secondary fermentation. For our 2010 Cloud9, we were able to carry out the malolactic in January after racking off into barrels and heating up the cellar. There is also a view amongst some wine makers that one can better integrate the fruit and oak flavours if malolactic fermentation is carried out in the barrel. We think the results give a unique flavour and finesse which has helped preserve the fruit character of such a fine wine. For 2011, nature has delivered an Indian summer in Bordeaux and it may not be possible to hold the malolactic back.

Wine is a very natural product influenced by the seasonal conditions, the conditions on the vine and our human interaction in the winery. That’s why every wine and every vintage is unique…and so much fun to talk about.