It may not be the most appetizing color to associate with wine, but a bit of brown can go a long way in making a clean, elegant wine—particularly as far as white wine is concerned. The idea, here, is to favour “brown juice” over “green juice” early on in the vinification process, meaning that oxygen is actively introduced into the must to remove some components (notably, phenolics) and to help the wines build up oxygen resistance for the long run.
This exposure to significant quantities of oxygen doesn’t apply to all white wines. Non-aromatic whites like chardonnay, riesling and marsanne or melon de Bourgogne are good candidates, but not aromatic varieties like sauvignon blanc, gewürztraminer or viognier, to quote a few examples.
Why those varieties and not others? As French sommelier Marc Massot, a Muscadet expert, explains, “melon de Bourgogne is relatively low in more fragile aromatic compounds like thiols and can thus stand exposure to oxygen better in the early stages than more aromatic varieties.” Indeed, producers of sauvignon blanc who like to preserve aromas of passionfruit and grapefruit, something that has become a signature for this variety in New World wines, will on the contrary reduce contact with oxygen as much as possible.
Many chardonnay and riesling producers actively – if not aggressively – aerate their musts right at the moment of pressing, causing them to take on a sometimes impressively dark brown color, as elements like phenolics are hit by oxygen, before precipitating out of the juice. However, there are a number of variations on this oxidative approach.
A tailored approach
Brian Schmidt, the winemaker (and vice-president) at Vineland Estate Vineyards, in Ontario’s Niagara region, points out that for his rieslings his method is “almost brown juice” – but not quite. He does seek to brown out phenolic components, but instead of providing high levels of oxygen at pressing, like many will do, he instead introduces oxygen at controlled levels, for limited times (20-30 minutes per day, on average), using a ceramic diffuser he puts into the tanks during fermentation.
Beyond the issue of phenolics, this also allows him to apply different levels of oxygenation to different lots, according to their ripeness, acidity levels and other factors like nutrient levels. In 2012, for instance, despite the ripeness of an extremely hot and sunny vintage, he added higher amounts of oxygen to his tanks, because nutrient intake in the grapes had been affected by drought conditions. Oxygen, in this case, was used to help create a healthy fermentation, as yeasts struggled more in a low-nutrient environment. When using diffusers, monitoring of dissolved oxygen is done on a regular basis to avoid excessive intake and thus, problematic oxidation instead of helpful oxygenation.
The same kind of applied oxygen management is also at the heart of Jason Diefenderfer’s approach. The winemaker, who works at Hope Family wines, in California, explains that he treats his musts differently according to various maturity levels and sun exposure, as he puts the juice in contact with air at the time of pressing, right after picking. Additionally, free-run juice is treated more gently, while pressings (which he defines as anything coming out of the press at pressures of 0.8 bars and above) are browned more actively to take out phenolics, which he doesn’t want in his wines. He points out, however, that he mainly works with non-aromatic whites like chardonnay and marsanne, which are “more robust”, with regards to oxygen exposure, and not affected as much by the loss of more delicate components.
In such situations, active use of oxygen is an ally of the winemaker, one that can help foster desired aromatic profiles and create cuvées that can stand the test of time.
Photo Credit: Flickr Ian Brown