Red wine and oak

Chateau Margaux

Friends tell me they prefer red wine with oak. I also hear people say that wine must spend time in oak or it won’t be good. But exactly what does oak taste like? Indeed does it have any taste at all? And is it really essential that red wine be aged in oak?

Oak is good for barrel storage because it’s strong yet can be bent without breaking and, when wet, expands to allow watertight joints. More importantly, it imparts flavours and allows small amounts of oxygen transmission so the wine can develop over time.

Sounds simple enough. Yet for the winemaker there are lots of variables to play with. Consider just five:

First, where does the oak come from? French oak has tighter grain and more wood tannins but more subtle aromas while the wider grain white American oak has less tannins and more pronounced aromas. Hungarian and Slovenian are also available.

Second, how has it been toasted? Toasting is an essential link between wood and wine. It destroys wood tannin molecules but makes available all kinds of aroma, from coconut and clove to dark chocolate and smoke, depending on the temperature and length of toasting. Wine aged in untoasted barrels has no complex aromas and its tannin is so raw that it is like biting into a piece of plywood. A ‘light toasted’ barrel gives herbs and spices, while medium toasting brings vanilla, cinnamon and smooth wood tannin. Wine aged in heavily toasted barrels acquires pronounced roasted coffee and caramelised flavours and less wood tannin.

Third, how ‘old’ is the barrel—that is how many times has it been used? New oak imparts the most aromas and wood tannins. Second and third filled barrels impart only about 50% and 30% as much, and those over five years old virtually none at all. But even the oldest barrel still allows that vital oxygen ingress, softening the wine over time.

Fourth, how big is the barrel? Small ones have a higher wood area to wine volume ratio so impart more flavour per litre than bigger ones in a given time. Small new barrels, such as the 225l barriques from Bordeaux, give the most intense aromas.

Fifth, how long should the wine be kept in barrel? Times range from a few months to a few years. Obviously the longer the time the greater the potential for imparting flavour and the effects of oxygen.

When you consider how many permutations of just these five variables are available to the winemaker you can see how much room he has for influencing the final wine.

Not all wines benefit from maturing in oak, let alone new oak. A concentrated and structured Cabernet Sauvignon may stand up to 100% new oak for 18 months, or even ‘200%‘ new oak by racking the wine from one new barrel to another. But this combination would overpower a more subtle wine like a Burgundian Pinot Noir, which might need only about 30% new oak to preserve its delicate structure and some winemakers would not use new oak at all. Similarly, Dolcetto might need no time at all in barrels in order to preserve its primary fruit aromas.

Unfortunately, some consumers have the perception that ’the more oak the better’, leading some producers to over-oak their wine, which may be pleasing at first but quickly gets tiring. I did a blind-tasting of nearly 100 2009 and 2010 St Emilion Grand Crus Classés with Thierry Desseauve, a leading French wine critic, and we both agreed that most were over-ambitious with the oak, but then that is what some consumers prefer.

There is a joke that if one wants wood, one should just bite into toothpicks—it’s cheaper than buying woody wine! Oak, like other components including acidity, alcohol, tannin and sugar, should be integrated and never stand out. The aromas of spices and vanilla should complement the wine by adding complexity, not kill the fruit. Perfectionist producers might choose to age their wine in a mix of American barrels, French barrels and stainless steel, and/or new and old oak in different proportions before finally blending to ensure the right amount of oak is imparted.

New barrel maturation is expensive and slow. For entry-level wine aimed at satisfying consumers’ desire for oak, the industry has come up with alternatives to barrel maturation using wood chips and staves. They can be French or American oak with different toasting levels exactly like barrels, but at a fraction of the price. Bags of oak chips, reminiscent of giant tea bags, can be placed in the tank during fermentation, so by the time fermentation is completed the wine has already acquired some wood aromas and the ‘wood ageing’ time can be much shorter.

Chips or staves are usually used in conjunction with micro-oxygenation, where measured amounts of oxygen are bubbled into the tank to soften the wine, mimicking the effect of barrel maturation. These techniques were considered inferior when first introduced, but most winemakers master them now and can make consistently reliable good-value wine.

Lesson to take home? Not all wines need or are suitable for oak ageing. A HK$100 wine ‘aged in new oak’ probably means chips not barrels, but that doesn’t mean it’s bad. As long as it is balanced and integrated, it’s a good wine. It is rather like fast food: the quality is there for the price you pay, but don’t expect it to taste and feel like Michelin starred cuisine. Jancis Robinson MW once said she has absolutely no problem with staves or chips as long as the wine is balanced and authentic.

Abridged version was published in the South China Morning Post on 16th August 2012