Acid Trip

Waiting for MLF, or secondary fermentation, to complete can be a bit nerve-racking.  As soon as it’s finished, you want to rack the wine into full carboys and then add sulfites to protect it.  The problem is that once you inoculate the wine with the MLF bacteria, you can’t tell by looking at it whether it’s working or not.  The books say it can take anywhere from a few weeks to a few months.  Fortunately, there’s a time consuming chemistry test you can perform to see how it’s progressing, so with my Chardonnay four weeks and the Pinot Noir two weeks into the process, I decided to do the test and get a progress report. 

The general idea of the test is to put small samples from three different types of acids and each of your wine carboys onto a special type of chromatography paper, than soak the paper in a developing solvent for several hours.  Once you remove the paper and allow it to dry, the samples will leave behind imprints at various heights on the paper, which you can read to determine what type of acids remain in your wine.  Since MLF is the process of converting malic acid to lactic acid, the fermentation is complete once the reading tells you the malic acid has disappeared. 

In my results shown here, you can see from the two columns on the far right that there is no yellow dot in the middle, which means my Pinot Noir samples have completed MLF.  After two weeks!  Really good.  The three columns in the middle show a strong presence of malic remaining, meaning that after four weeks the MLF in my Chardonnay has barely begun.  Really bad.  I’ve never had a stuck MLF before, so I’m not actually certain what to do about it, but I’m assuming the first reasonable response is to cry.