Why we age wines in barrels and the effect it has on the drink is something very important to know when understanding why wine tastes the way it does. With few exceptions such as Chardonnay, it is really only red wines that are aged this way.
During the Roman empire, vast amounts of people, weapons and wine were moved across the globe. Wine was important for many reasons, one of which being that it was safer to drink than water. The Romans originally used clay amphoras to transport their wine, primarily because they were easy to produce and offered an airtight seal. As the Romans moved further north into Europe, they found that the weight of the amphoras made them challenging to transport by land. Eventually they discovered that the Gauls, the inhabitants of modern day France, were experts in bending oak to produce wooden barrels. Oak forests grew thick and plenty throughout Europe and this, combined with its waterproof properties, made it an ideal material for transporting liquids. It wasn’t long before the Romans realised it had another benefit: it imparted a special taste to the wine that before then had not existed.
To understand what effect barrel ageing has on wine, one must first familiarise oneself with its three main sets of aromas: primary, secondary and tertiary. Primary aromas are those associated with the grape varietal, think the strong perfumes of
fruits and herbs. Secondary aromas are those that are produced as a byproduct of fermentation, yeast and butter are often easy to identify. Tertiary aromas are those that come from the ageing process. These include the more sweet and toasted aromas such as chocolate and caramel that are imparted by using wood barrels.
When it comes to ageing, there are different types of wood used. Acacia and Chestnut are both fairly common but Oak is the main type used for wine barrels. Wine is aged in wood to add different aromas and flavours, because unlike other fermented products such as beer, no flavour additives are allowed in wine production. The reason that oak imparts aromas to wine, is due to an agent called lactones which is present in all oak and is released when the wood for the barrel is toasted. The amount of toasting will vary with more toasted barrels imparting more aromas to the wine.
Barrel ageing helps the wine mature before it is bottled. This is because it allows micro oxygenation—when wine is stored in a barrel, it is not in a completely airtight environment. Oak has tiny pores which allow oxygen into the wine which results in a reduced astringency in wine. Wines that are not aged in barrels are more astringent, meaning they have a sharper taste on the tongue. Micro Oxygenation allows the wine to become more smooth and pleasant to drink. The other reaction that occurs in barrel ageing is a process called malolactic fermentation. This is a chemical process that changes malic acid – think tart unripe apple taste to lactic acid – the creamier, softer flavour profile.
Ageing adds layers of aromas to wine. When people say they can smell vanilla, caramel, cloves, cinnamon, dried fruit or leather – these are all due to the ageing process. There is also a difference in the type of oak that is used. New oak barrels impart more flavours than old oak barrels. It is also interesting to know that oak barrels can be used for up to 100 years although this is not often the case in wine making. Typically when winemakers are done with their barrels, they sell them for use in the making of another beloved drink: whisky.