Oxidation and reduction may be the source of potential faults, but they can also be tools to sculpt a wine’s style and give it a distinct personality. Or even to make it fit fashion.
A particular fashion-chasing bent recently caused Jancis Robinson, one of the world’s top wine writers, to express fatigue in a recent column called Struck-match wines – reductio ad absurdum? Concentrating on chardonnays, and in particular white Bourgogne, she wrote that the reductive trend in these wines “may well have gone too far.”
‘Buttery’, ‘rich’ and even ‘toasty’ used to be terms of approbation for these sorts of wines, but no longer. An increasing proportion of them nowadays are notably high in acidity, have no trace of the toastiness of obvious oak, are almost lean on the palate and, crucially, have the tell-tale flinty smell of recently struck matches. These sulfide notes are associated with so-called reductive winemaking in which wines are protected from oxygen during aging.
In Burgundy, a bit of matchstick has become more and more associated with high-end wines. It is a signature of many highly sought-after wines from producers like Coche-Dury, Leflaive, Roulot, Arnaud Ente or Colin-Morey, to name a few. Thus, what was more often than not seen as a fault is now elevated as a sign of quality – although in some places like Chablis, it could be argued that flinty, mineral notes have always been part of the wines’ character.
Fighting premox or looking for points?
In any case, why the shift? In her article, Jancis Robinson (quoting Meursault producer Jean-Marc Roulot) points to a connection between the rise of reductive winemaking and the concerns that rose in the 1990s about premature oxidation of white burgundies. Although the reasons behind the “premox” or “pox” crisis remain a matter of debate, a number of producers clearly responded by tightening things up, protecting the wines from oxygen and thus, moving towards the reductive side of things. Long, slow and delicate pressings, protection from oxygen through vinification and aging, and even finishing the wine’s aging in tank, rather than barrel, were some of the techniques used to achieve this. Relatively high SO2 additions may also be linked to the appearance of the sulfide character in some of the wines.
Once these chardonnays with a reductive edge started gaining approval, the style spread well beyond Burgundy. In the 2000s, it became more prevalent in Australia, and also moved to several cool-climate regions that turned to white Bourgogne as a model, rather than the hedonistic, peachy, tropical, oaky style that had once been so sought-after in places like California.
Critics and sommeliers approved, consumers paid attention, medals were won in competitions, and reductive notes became part of a trendy style of chardonnay. That style also included a general shift to fresher, crisper wines, obtained through earlier picking dates and moving vineyards to cooler spots, but also through techniques like the suppressing of malolactic fermentation, as well as the avoidance (or minimal use) of lees stirring, which builds up fattiness in the wines’ texture.
It’s interesting to note that while these various elements dovetailed into the current, fashionable style of chardonnay, aspects like added freshness or lighter texture are not intrinsically linked to reduction or oxidation. One could have reductive notes on a very ripe wine, as well as on one with a fatty texture – and malolactic fermentation is, in fact, a reductive process welcomed by some winemakers as something that can help protect the wines and help them better navigate long barrel aging. In other words, reduction is one element that defines this style of wines, but it is by no means the only one.
Use with moderation
In any case, using a reductive approach requires a bit of a balancing act, and a delicate hand as well. As Nomacorc enology researcher Maurizio Ugliano, points out, going to the reductive side isn’t like flipping a switch, it’s moving things along a scale. “Struck flint is not an extreme but an intermediate level of reduction. In reality there are several more degrees of reduction (or oxidation), which are linked to degrees of oxygen exposure that exist in between certain extremes.”
This scale has a lot to do with the various compounds involved in a particular wine, in particular sulfur compounds. Without going too far in the highly complex chemistry of reductive compounds, it can be said that some of these compounds are more implicated than others in reductive aromas. For example, hydrogen sulphide (H2S) and mercaptans which can contribute to unpleasant rotten eggs and cabbage notes, representing an extreme degree of reduction. Other compounds such as benzene thiol and fufuryl thiol, which contribute aromas of bread crust, smoke or struck flint, represent the in-between zone where, depending on wine style, they can contribute more or less favorably to perceived quality. Interestingly, recent studies seem to indicate that benzene thiol could be a key compound to those struck match attributes of some Burgundy chardonnay.
Moving further away from the extreme unpleasant reduction, the fruity thiols that provide notes like passionfruit in sauvignon blanc are also part of the sulfur compounds of wine, but they are generally imparting pleasant aromas that are highly sought after by consumers. One interesting aspect of these sulfur compounds is their reactivity towards oxygen. It appears that the small compounds such as H2S and mercaptans are removed more easily than the others when the wine is exposed to small amounts of oxygen. Therefore, precise control of oxygen in the bottle, for example by selecting a closure allowing small and consistent amounts of oxygen, can allow preventing extreme reduction without compromising the more interesting flinty and fruity aromas. When a wine has a tendency to rapidly climb up the scale towards the extreme degrees of reduction, oxygen starvation can easily lead to unpleasant characteristics: cabbage, onion, garlic, even swampy, stinky reductive notes, “along with a harsher mouthfeel”, as Maurizio Ugliano points out. The challenge is that each wine has its own scale, as grape variety, winemaking style and other elements modify the chemical composition and the relationship to oxygen.
Also, reductive notes can’t replace quality grapes and they are not, in and of themselves, a sign of excellence. Wine’s many other dimensions also have to be present, to make a great wine. As Jancis Robinson writes, “wines in which the reductive character completely obliterates the natural fruit can be both wearying and boring to taste – and if overdone, it can lead to bitterness.” Few might have thought that flint and struck-match would become such sought-after characteristics, thirty years ago, but it’s even harder to think, thankfully, that “bitter”, “swampy” and “harsh” will ever become fashionable descriptors.
Photo credit: Burgundy Report.