Winemaking and the different types of wood
Winemaking is a complex business. Some call it art; some call it science. From harvesting to bottling, there are so many decisions that winemakers need to make to produce the wine on which they want to put their stamp of approval.
Let’s talk about wood.
There are so many different types of wood products that winemakers can choose from that some companies employ wood specialists just to help with the decision. What are the different types of woods? Is it just oak wood, or are there other options? Does the type of oak matter? What about toasting? Are we just talking barrels or are there other alternatives?
So many questions!
Winemakers usually use oak wood when they craft their product. The permeability and flavour profile of toasted oak combines the best with wine. Most countries only allow winemakers to use oak wood as part of the winemaking process. But that doesn’t mean that there aren’t other types of wood that could work for winemaking. Scientists are also experimenting with chestnut wood to see what the effect would be on wine. So far they found that chestnut wood imparts more volatile phenols – not always a good thing!
Types of oak
The two most commonly used types of oak are French Oak (of which there are two main species) and American oak. The major difference between French and American oak is that French oak has a tighter grain which means that the wine comes into less contact with French oak than with American oak in the same size barrel. So, American oak often imparts stronger flavours due to the increased surface area available. American oak also provides different flavours, typically coconut, whisky lactones and vanilla compared to French oak which imparts heavier spicy and chocolatey flavours. Another increasingly popular type of oak is Hungarian oak. Hungarian oak kind of falls midway between American oak and French oak regarding grain and also tends to provide heavier flavour tones, similar to French oak.
Cooperages usually toast the oak wood used for making barrels and other oak products before use. Untoasted oak can give a green, pencil shaving character to the wine. There are typically four shades of toasting for oak products – light, medium, medium plus and heavy. Toasting breaks down the lignin structure of the wine, reducing the planky odour and releasing volatile compounds such as oak lactones, vanillin and ketones responsible for coconut, vanilla and caramel flavours respectively. Toasting also releases more phenolic compounds which add a spicy character. As the toasting level increases, new types of compounds like furfural and its derivatives forms which impart a roasted coffee, smoky character.
Winemakers are not restricted to oak barrels; there are many other oak alternatives on the market. Winemakers can use oak chips, shavings or extracts during fermentation and age their wines in stainless steel tanks with oak staves or oak chips. These oak alternatives are a more affordable way to get the benefit of oak maturation – oak flavours plus smooth tannins.
Winemakers are spoiled for choice when it comes to using oak products. The trick is to use the right combination of oak treatments for the right wine. And that is why winemaking is considered an art.