A Different Kind of Bug

People often stop me on the street and say, “What do winemakers talk about in late November?”  Well, probably the number-one question we ask of each other in this profession is “So, d’ya getcher deer?”

Just kidding. It’s “How are your MLs doing?”

MLs in this case are winemaker shorthand for malolactic fermentations. You may recall seeing a picture of Tricia in an earlier post, initiating the process from on high with little cups of freeze-dried bacteria. That was a few weeks ago: by now, our MLs are either well underway or wrapped up entirely.

What’s the point of this procedure? A guaranteed modest reduction in the acidity of the wine, associated with the conversion of malic acid to lactic, is rarely a bad thing in our cool climate. But we also expect an increase in aroma and flavor complexity.

Not all wines need to undergo this extra microbial treatment, but we normally ask it of our reds and our barrel-fermented Chardonnay. In Chards, the added complexity often presents as a mild butter or butterscotch character (a little goes a long way), whereas in reds the change is harder to describe but definitely a good thing. We can transform Pinot noir, for instance, from a simple cherry- and berry-flavored concoction into one that’s more reminiscent of earth, cola and spices with the aid of bacteria, especially if ML happens in conjunction with barrel maturation.

The organism we recruit to do the work has the scientific name oenococcus oeni, with both the oe- prefixes pronounced like ee-. Our friend Chris Stamp at Lakewood Vineyards, who has a decidedly un-eunuch-like devotion to his craft, went ahead and renamed it weenie coccus weenie, despite the fact that bacteria don’t actually have undersized sexual organs, and in fact possess none at all. (To give you an even clearer idea of what’s on Chris’s mind much of the time, he’s still upset that he didn’t trademark the name ‘Viagra’ for a proprietary blend of Vignoles and Niagara, years ago.)

Malolactic bacteria are dwarfed by yeast cells, though neither is visible to the naked eye. It takes a serious microscope to get a look at oenococci. They’re fussier and more fickle too, somewhat like the stereotype of a Russian mail-order bride: apt to sulk if they don’t get the things they want and deserve. Thus we keep the cellar at a balmy 70 degrees F, and play soothing music rather than the more jarring stuff, and perhaps ply them with baubles.

Most wineries with modest budgets use a process called paper chromatography to monitor the progress of this transformation. It’s a fun though somewhat laborious technique involving a smelly solvent, some tiny glass tubes called micropipettes, and a few run-of-the-mill items like pickle jars, staplers, blow dryers and clothes pegs. Here are a few visuals:

Preparing to Evaluate Our MLs

Ten barrel samples of wine in the yogurt cups are
carefully transferred to the spots on the paper.

Chromatography Underway

The strong smelling solution (hence the lid) is drawn upwards.

Not a Standard X-Ray

Ten columns of spots, left to right.  Individual columns represent
a different wine sample, in various stages of ML.  Samples 2, 8, 9, and 10
aren't finished yet, as indicated bya spot midway up: malic acid.

Another quick and easy way to find out if ML is progressing in a barrel is to press your ear tightly to the bunghole. A telltale crackling sound indicates the evolution of carbon dioxide gas: either alcoholic fermentation is still finishing up (unlikely in a wine this late in the year) or the lactic acid bacteria are having at it. No way is this a sensitive enough diagnostic by itself – it’s the wine equivalent of gauging wind speed by the flapping of a flag in the breeze. It simply tells us if something is happening or not happening.

Moreover, the ear-to-the bunghole technique carries the risk of a very specific pseudo-malady. Without being consciously aware of it, we often ‘apply’ a bruise-like ring of red wine to the outer ear when we listen in on a barrel. It makes us look either like we have an exotic disease, or like our head area has been worked over by bullies. ‘Red Ear’ is a minor badge of honor around the winery, but it’s important to wash it off before emerging into the outside world, or risk getting some odd looks if we stop in at the supermarket on the way home. Then again, it might mean that we get the Express Lane all to ourselves.

Barrel Music

Sounds like a tired pastiche of every sea shell you've ever
listened to; this barrel needs to up its artistic game to be as
worthy of critical attention, radio play, and trite metaphors.

Red Ear

Pseudo-malady or awesome pirate name?  You decide!

By: Peter Bell, Winemaker


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