Syrah - Day 21 - Malolactic Innoculation

Despite the large emphasis we have been putting on sanitation up to this point, not all bacteria are bad for wine. There are some bacteria that have positive effects on wine. One such bacteria that is often used in wine making is Oenococcus oeni, or the bacteria responsible for malolactic fermentation.

This bacteria changes the harsh malic acid present in the wine into lactic acid. This transformation reduces the bitterness of the wine, changing sour apple flavors into smoother buttery flavors and adds to the wine's fruitiness. It also slightly raises the pH of the wine, since lactic acid is a weaker acid than malic acid.

Not all wine should undergo malolactic fermentation. Almost all red wines benefit from it, but some light varietals of white wine lose their crisp edge when the acids are reduced. Generally these are Pinot Gris, Sauvignon Blanc and German whites that suffer at the hands (flagellum?) of the bacteria. Those light wines are also unable to mask some of the other flavors created by the bacteria, such as diactyls that get tucked under the rug in most red wines.

Timing of the malolactic fermentation is debatable. There are a few vintners that add malolactic bacteria at the same time as the yeast, there are a few problems with this approach. If you add the malolactic bacteria at such an early stage in the wine making process, you severely hamper your ability to use sulfites to prevent unwanted bacteria from taking hold, since the sulfites would kill the malolactic bacteria alongside any undesirable microorganisms. Another danger of adding the malolactic bacteria too early is it can start competing with the yeast for sugars and then use those sugars to create acetate acid or the main ingredient in vinegar. Generally, from the sources I've read, you want to start the malolactic fermentation around when the sugar in the must/wine is near zero. This can be at the end of primary fermentation, during secondary fermentation or even after the first or second racking.

For our batch of Syrah, the malolactic fermentation is being started 8 days into the secondary fermentation. This is based somewhat on convenience and somewhat on the need to do malolactic fermentation before the temperature gets too cold for the bacteria to survive (With a 40 F morning today, that may be too late. Seeing as O. oeni thrive at roughly the same conditions as yeast [60-80 F]).

In order to inoculate some carboys with malolactic bacteria, first sanitize the measuring dish. Then calculate the amount of freeze dried Oenococcus oeni needed to add to each carboy: Our 2.5 g package was meant for a 66 gallon batch, that breaks that down into .12 grams of freeze dried bacteria for 5 gallons; .7 for the three gallon carboy; and trace amounts to the three 750 ml bottles. Then it is a simple matter of weighing the bacteria dosage and adding it to each of the carboys. Once added, it quickly dissolves and (hopefully) sets about its business. Ideally the cold won't put an undue stress on the bacteria and malolactic fermentation gets underway soon in our wine.