The Mystery of Malolactic

It used to be of course, when malolactic fermentation was less well understood, that winemakers just let the process take its natural course and hoped for the best. With greater understanding of the science has come a desire if not actually to control it, at least have it take place in a way that is optimal and with the least risk of damaging the wine. But there seem to be quite different views as to how best to achieve those ends.

For whites of course whether to allow the wine to undergo malolactic is primarily driven by the style of wine one his trying to make.  Going through malolactic will reduce the sensation of harsh acid in the wine - and indeed raise it’s pH measure - and the by-product flavors produced give a creaminess to the wine’s texture. As you might expect, where the winemaker is seeking to make a crisp wine at cool temperatures with good freshness the malolactic process is likely to be blocked. Conversely, if the wine has searingly high acid and would benefit from a higher pH and more textured mouthfeel to compensate, the malolactic fermentation conversion process will be allowed to proceed.

For whites, therefore, whether the wine goes through malolactic seems a fairly straightforward decision - it is a style choice. Some Champagne houses block malolactic and some do not. Some winemakers, wanting to preserve the acid quality, block malolactic but find other ways to give more richness to the wine - such as having the wine rest for long periods in oak on its lees. In still other cases high levels of fruit ripeness may make adding further texture by running the wine through malolactic undesirable.  And so it goes.  The “Yes/No/Partially” decision for whites is purely a style choice and will depend on vintage and grape variety.

But at another lev this is a process that requires considerable care in decision making.  For reds the reduction in pH resulting from malolactic fermentation is far less than for whites. The principal benefit of having a red wine go through malolactic is the increase in texture that the biological process imparts to the tannins and the improved color intensity of the wine. The wine seems more supple and to have a broader mouthfeel. So pretty much every red wine goes though malolactic.  Emile Peynaud was of the view, as expressed in a paper in as early as 1939, that “it is not exaggerating to say that without malolactic fermentation there would be hardly any great reds of Bordeaux”.  But it really was not until the late 1960s that the process was properly understood. 

Even today, the malolactic fermentation can be a period of some risk to the health of the wine. As with primary fermentation, it is not without its own concerns. Not only are there four different strains of bacteria that can perform the job ( but only one you really want to do it) each of these does not produce the same bi-products. And wine - being high in acid and alcohol - is hardly an environment best suited to the growth of the desired bacteria. If there is still sugar left in the must then the wrong strain of bacteria can produce volatile acidity. So there are some things to worry about. Having decided that the red wine is to go through malolactic, one is left having to decide when, in what vessel and for how long to allow it to take place. Not too much in this space can actually be proven to have benefits or mitigate risk, which makes it difficult to say there is a single better way and a worse way or time to perform malolactic. Extraneous conditions will also matter, in particular how cool is one’s cellar in the relevant season when malolactic is targeted to occur. But many well known and respected growers have expressed differing preferences on these matters, depending on which desired consequence or risk reduction they regard as paramount. Which reinforces that there likely is no single “right” way to do malolactic.

I set out below some of these variables. 

Vessel. Certainly for Nebbiolo, allowing the malolactic to take place in small new oak barrels does seem to me to influence the wine considerably. The wines seem quite marked by the barrel. Those who use new or partially new barrique for aging the wine more generally, likely also have the malolactic take place in those same barrels. This is common in Bordeaux also. The technical management at Smith Haut Lafitte believe that it is preferred to do malolactic in small barrel because it results in superior integration of oak tannin - presumably a valid point of view if you are using new oak and wish to impart tannin from the wood to the wine.  Others prefer the wine to be housed in larger inert vessels during malolactic and will rack the wine into these during the process, then move the wine back into wood afterwards. So there are differing views as to choice of vessel, which perhaps can be categorized as either preferring the influence of smaller wood during malolactic or not.

Timing. In Bordeaux the malolactic is often encouraged to occur early, not least because the Bordelaise want the wines to be fully presentable for the April “En Primeur” tasting season. So they heat the cellars to induce malolactic to start. Many in Burgundy also prefer early malolactic - most famously at Domaine Rousseau. There is an argument in support of this that an early malolactic allows the wine subsequently to rest on lees that include post malolactic bacteria for a longer period prior to bottling than if malolactic occurs later. Benjamin Leroux has suggested it may be optimally beneficial for the time on lees to be post malolactic ie post conversion of the malic acid to lactic acid and in the presence of the bi-products resulting from that conversion having already taken place. Today, with so many warmer vintages, there is less malic acid in the grapes and so fewer residual by-products result from the conversion. So the risk of contamination through the malolactic process and subsequently retaining those by-products with the lees is correspondingly reduced. The “dead” bacterial population is simply lower. In contrast, most rack the wine after malolactic precisely to eliminate any potentially adverse bi-products from the malolactic. Others prefer the malolactic to occur later. In this camp we have Jeremy Seysses and Christophe Roumier, who takes the position a later malolactic allows for it to progress more slowly and generates better color retention. And since you have to sulphur the wine after malolactic the less time between the malolactic’s end and bottling the less total sulphur must be added. Christophe Roumier himself is also pretty sure a later and longer malolactic reduces the risk of volatile acidity. But there seems to be no consensus as to timing.

Duration.  In relation to cooler cellars, you sometimes hear stories of wine still going through malolactic for the better part of a year.  Some prefer the process to take place in its own time and are willing to let it run an extended course. Others prefer it be brief - recognizing that the process is an unsettling period for the wine and a time that is not without risk. 

No consumer today says “ I prefer wines that have gone through late malolactic” or “I prefer wines where the malolactic was completed early and quickly” because I submit it is quite difficult in later tasting the resulting wine to infer precisely how the malolactic was conducted. Nor is there is yet even consensus as to the actual consequences of malolactic having taken place in a particular vessel or early or late or for a particular duration. Yet the growers themselves all do have preferences. They have to have because they must make decisions relating to these variables. For the time being, to the consumer, optimally managing malolactic is in that category of the dozens of unseen decisions a wine maker has to make, which in aggregate distinguish the competent from the great. As to further attributing consequence to winemakers’ every decision, in the context of the issue of malolactic the endlessly curious consumer may just have to admit defeat. Which is just fine with me.