Ah, the timeless pairing of American oak and Zinfandel. It’s a taste combination that’s got more than 100 years of history in U.S. winemaking and if the number of Zin labels that sport something like “aged for 18 months in American oak” is any indication, then its second century is off to a good start. Zinfandel, as a powerful, tannic and jammy red is a good canvas for the bold, broad brushstrokes of American oak — the American wood’s aromas of vanilla, clove and butterscotch are often too overpowering for more elegant, lighter varietals like Pinot Noir or Nebbiolo.
Most wineries choose to age their Zinfandels in at least 50% American oak (the other percentage being made up by French or Hungarian) in the form of 50-gallon (190-L) barrels. Using oak barrels is by far the most traditional way of aging wine as they impart not only aromatic but also structural and mouthfeel benefits. However, it’s also more and more common for winemakers, especially those that are making quantities too small to conveniently fit into a standard barrel, to use oak powder, chips or cubes to get some of the same flavor and aroma benefits without buying or caring for barrels. To this end, oak adjuncts (industry jargon for non-barrel oak) are often sold at different levels of toasting, just like barrels. The heavy-toasted oak imparts more “burnt” aromas like coffee and chocolate and medium-toast products contribute smells more mellow on the caramelized scale like allspice, dulce de leche, toasted bread and vanilla.
The question then becomes, how to best approximate what a barrel would do to a wine using oak adjuncts and more specifically, at which stage should the oak bits be added and how long should they be left in a wine? As you might guess, there is no one correct answer except the one that always holds true: You must go by taste and have patience.
In my experience, with bold, big red wines, it’s safe to add oak chips at the rate of 1–3 grams per liter. The oak bits can simply be floated on the surface (as long as you stir them occasionally) but it’s best if they’re tied up in a small cheesecloth sack, tea bag-style, and submerged underneath the liquid by means of a food-safe weight like a few glass marbles or a stainless steel hose fitting, depending on the size of your “tea bag”. Sample the wine at least once a week to determine when it’s “done” according to your tastes. Depending on the wine in question and the toast level of the oak, this could be anywhere from 1–6 weeks. Ideally, the effects will be subtle and the oak aromas and flavors will only serve as a grace note on top of all the other wonderful things already present in your wine. Now for a few caveats, if I may:
Realize that fermenting wine will be warmer than wine that has been through the primary fermentation and adding oak cubes, chips or powder during the active fermentation, with the increase in temperature, might cause you to over-extract before you realize it. This is why, especially if you’re new to winemaking, I suggest you add oak adjuncts after the primary fermentation is complete and you’ve racked the wine off of its gross fermentation lees — i.e. when the wine is about four weeks old. This way, you don’t have any weird fermentation aromas, a bulky cap and lots of chunky lees (in addition to high temperatures) to get in the way of determining when you’ve added enough oak to your wine.
Similarly, wine that is high in alcohol will more quickly absorb oak flavor and aroma than those that are not. Alcohol is a better solvent than water and as a result, it’s easier to mistakenly over-oak higher alcohol wines than those that are hovering around a moderate 11.5–13%. Wine that’s above 13% may need to be tasted more frequently in order to avoid getting too much oak character into the wine.
Also keep in mind the surface area of the oak product you’re using, as pieces of wood that are smaller, when added at the same weight to liquid ratio as larger pieces, will more quickly impart wood aroma and flavor than larger-sized particles. If you’re working with a very fine oak powder, it’s reasonable that 0.1–0.3 grams per liter will be more than enough to give you the slight oak flavor you’re looking for. Since I don’t know the size of your oak cubes, it’s difficult to suggest an addition rate. The good news is that you can always add more later. That’s the beauty of using oak products; the danger is that you can never go back once you’ve added too much.
For more of the Wine Wizard’s wisdon, check out the latest issue of WineMaker magazine, available now at better winemaking supply retailers and newsstand locations.