Wine Yeast, Malolactic Bacteria & Additives
Wine Yeast - Alcoholic Fermentation:
When we add wine yeast to our must, the yeast consume the sugars and create alcohol and CO2 as by-products. This transformation of sugar into alcohol by the wine yeast is what turns the juice/must into wine and is the basis of all winemaking. Each wine yeast has its own unique set of flavors and aromas, so take a look at our Yeast & Grape Pairing Manual to help find the one(s!) that are best suited to your winemaking style. Remember, it's the wine yeast who are actually making the wine, we as winemakers just provide the introduction and handle the details!
Malolactic Bacteria - Malolactic Fermentation:
In addition to wine yeast, there is another organism that we can use to round-out and add complexity to our wines: malolactic bacteria. Malolactic bacteria consume malic acid (naturally present in the grape) and convert it to lactic acid. Lactic acid is roughly half as strong as malic acid, so when it reduces/replaces the malic acid in the wine the pH goes up (and the TA goes down). The result is that the wine becomes less tart, softer and fuller than it was before the malolactic fermentation. Depending on the grape varietal and the style of wine we are looking to make, this may or may not be a good thing. As a general guideline most red wines undergo a complete malolactic fermentation and benefit from doing so. White wines can vary from full (barrel-fermented Chardonnay), partial, or no malolactic fermentation ("New-World" Sauvignon Blanc). There is no "right" choice - it just depends on the style of wine your are making. Complete information on alcoholic and malolactic fermentations can be found in our Red Winemaking and White Winemaking Manuals!