A long last post for the week. It involves big concepts that are very important to Nikey, our wine maker and we wanted to involve you in the wine making process a little. We are going to talk fermentation and processes that make our wines so easy to drink. Have a read and hopefully this post will give you something to talk about at dinner soon.

Malolactic fermentation is commonly referred to as “MLF”, or (in winemaker’s speak as) “malo” (pronounced ma-low). MLF usually occurs shortly after the end of the primary fermentation (when the grape sugar is converted to alcohol by yeast). It is undertaken by the family of lactic acid bacteria (LAB); Oenococcus oeni, and various species of Lactobacillus and Pediococcus. The primary function of all these bacteria is to convert one of the two major grape acids found in wine called L- malic acid, to another type of acid, L+lactic acid. This conversion is accompanied by the production of carbon dioxide (so hence the term, fermentation).

Wines that typically undergo, and are improved by MLF, are the full-bodied dry whites and medium to full bodied dry reds. But it must be stressed that not all wines benefit from MLF. Malolactic fermentation tends to create a rounder, fuller mouthfeel. It has been said that malic acid tastes of green apples – indeed, malic comes from the Latin word for apple, mālum, and is present in apple juice – and this can be tasted in the wine. By contrast, lactic acid is richer, even unctuous, and more buttery tasting – corresponding to its presence in milk, as reflected in the word lactic being derived from the Latin word for milk, lac, and it is present in sour milk.

In addition lactic acid has a mouthfeel “softness” about it in comparison to the oft described “hard” and “metallic edged” malic acid. In short, MLF results in a natural de- acidification and softening of the wine’s palate. Grapes produced in cool regions tend to be high in acidity much of which comes from the contribution of malic acid. For wines produced from such grapes, de-acidification via MLF is particularly useful as it results in a more balanced and palatable wine.

There is also a major practical reason why MLF is encouraged during the making of many wines, and in particular reds wines that have previously undergone malo in tank or barrel are far less likely to go through malo when in bottle. The onset of MLF in the bottle is disastrous as the wine will appear to the consumer to still be fermenting (as a result of CO2 being produced). The wine may also lose its fruit integrity and take on the unpleasant lactic aroma of cured meats.

Malolactic conversion is accomplished by lactic acid bacteria (such as Oenococcus oeni), which consume malic acid to liberate energy. This can occur naturally. However, in commercial wine making, malolactic conversion typically is initiated by an inoculation of desirable bacteria.

So next time you have that amazing “mouthfeel” on our Chardonnay, malolactic fermentation is the reason behind it.

Next, onto Carbonic Maceration, which is something Nikey is quite passionate about.

Carbonic maceration is a winemaking technique, often associated with the French wine region of Beaujolais, in which whole grapes are fermented in a carbon dioxide rich environment prior to crushing. Conventional alcoholic fermentation involves crushing the grapes to free the juice and pulp from the skin with yeasts serving as a catalyst in converting sugar into ethanol. Carbonic maceration ferments most of the juice while it is still inside the grape, although grapes at the bottom of the vessel are crushed by gravity and undergo conventional fermentation. The resulting wine is fruity with very low tannins. It is ready to drink quickly but lacks the structure for long-term aging.

During carbonic maceration, an anaerobic environment is created by pumping carbon dioxide into a sealed container filled with whole grape clusters. The carbon dioxide gas permeates through the grape skins and begins to stimulate fermentation at an intracellular level. The entire process takes place inside each single, intact berry. Ethanol is produced as a by-product of this process but studies have shown that other unique chemical reactions take place that have a distinctive effect on the wine.

Flavor compounds derived from volatile phenols like benzaldehyde, ethyl cinnamate, ethyl vanillate, methyl vanillate and vinylbenzene emerge and are emphasized in the fruity flavors commonly associated with wines produced from carbonic maceration-like banana and kirsch notes. While the levels of harsh malic acid in the grape is decreased by 50%, the overall pH level increases by about 0.25 units. The glycerol levels are increased ten folds and the grapes juices gain about 2% in potential alcoholic strength. The resulting wine is generally fruitier, with brighter coloring and less tannins than conventionally produced wines.

Did you get all of that? I hope so, because Nikey will be asking questions when you come to visit us on the farm, but please, make an appointment as this time of the year is just crazy.

We haven’t managed to get to the barrels this week, but be sure to check in on Monday for that.