A California Winery Blog

Winemaker Bruce MaGuire periodically checks the red wines from the 2007 harvest for completion of malolactic fermentation. Some varieties will undergo this secondary fermentation, the conversion of malic acid to lactic acid , very quickly. Others especially those varieties harvested late are slower to undergo this process — one reason is that, because it is later in the season, it is colder and cold inhibits fermentation.

There was a time, and not so long ago, when malolactic fermentation was not as understood as it is today – it was discouraged – with the unfortunate result that it sometimes occurred within the bottle and spoilt the wine. The benefits today, of a carefully controlled malolactic fermentation, are well recognized. And aside from a more stable wine it enriches the wine with more complex flavor and balance.

Malic acid is most easily recognized in apples. Some white wines are also encouraged to go through malolactic fermentation especially those rich buttery Chardonnays. If fruit flavors, however, are essential such as in Riesling, Rosé, and Sauvignon Blanc, the wines are kept chilled, until bottling, to prevent this from occurring.

The photo below is of Bruce in the lab, at Lafond Winery, ’spotting’ the different barrels. He puts several drops on each ’spot’ on a special paper. Each spot represents a different barrel, and when he places the paper in a solution it will tell him if the fermentation has been completed, or how far it has gone. He uses a small capillary tube, that he rests on the board at his side, to deposit the ‘drops’ on the paper. Slow but effective.