As with everything to do with wine, there’s never a straight answer. Most people have heard somewhere that ‘wine improves with age’ but don’t know why, or what, ‘improves’ actually means. There are enthusiasts all over the world who regualrly buy wine with the intention of storing the wine for many years before drinking it. The love of mature wine is not just for die hard enthusiasts. Once you understand what’s happening, you may feel the need to start a cellar! To keep this post from blowing out into some kind of short story, I’ll just discuss red wine.
What is wine made of?
To find out what ‘improves’ and why, we need to look at what’s in wine. We know it starts as grapes. (Most) red grapes are red because of something in the grape skin called ‘anthocyanin’. The skin (and seeds) also contain ‘tannin’ which is related to anthocyanin and together they form complex polymers. Additionally, red grapes contain tartaric acid and malic acid, as well as natural sugars, which are converted to alcohol by yeast during fermentation. As this is not a scientific paper, we’ll lump the remaining components together as ‘flavour, aroma and texture compounds’.
What happens during ageing?
While the description of wine in the paragraph above is oversimplified, wine is amazingly complex. There are 800-1000 different compounds that can be found in red wine. Coming back to our basic parts, generally we don’t see much change in the alcohol component. However, this can affect other components during ageing.
The acid does seem to soften during ageing but this is a slow process. The largest changes are seen in tannin (and texture), colour, and flavour and aroma compounds. The colour shifts from bright red and purples to mahogany, brick and brown as the wine gets older. The tannin becomes less evident and the texture in the mouth changes, shifting from dry, astringent and ‘grippy’, to smooth and round. Tannin affects how slippery your saliva is. Lots of tannin in a young wine causes the mouth to become dry. Mature tannin is softer and affects the saliva less.
The interesting part for me is the changes in flavour and aroma; the fresh, ‘primary’ fruit characters become less ‘simple’. For instance, raspberry, plum, blackberry notes become more complex to exhibit characteristics of leather, soy, tobacco and cigar box.
What causes these changes?
Ultimately, time in the bottle provides the conditions for the changes to occur. I know I keep saying this but, once again, there are many changes going on and numerous factors affecting those changes.
Firstly, there seems to be two main maturation processes happening. One due to the presence of oxygen, and the other independent of oxygen. Oxygen will be present in the wine at bottling. There will be an amount of dissolved oxygen in the wine and possibly some oxygen in the ‘vacuity’ (space between the top of the wine and the bottom of the closure). The amount in the vacuity depends on the bottling process and can be controlled to an extent. The type of closure affects the amount of oxygen ingress over time.
Cork, technical corks, screw caps, glass stoppers and other ‘non-cork’ closures have all been shown to allow oxygen ingress at different rates. Generally, technical corks and screw caps show the lowest oxygen ingress per day, but the screw caps can allow a big hit of oxygen at bottling as the vacuity is usually not eliminated, or the air replaced with inert gas. The oxygen in the wine will react with flavour and aroma compounds and can cause a reduction in their intensity. Oxygen also alters the colour, changing it from bright red and purple towards the brown spectrum. And it reacts with tannin causing it to become ‘softer’ and less astringent.
Even when there has been very little oxygen ingress at bottling, or through the closure, over time the wine still matures. While tiny amounts of oxygen are present, the tannins (natural anti-oxidants) do their best to react and protect the wine. The changes in the fruit flavours and aromas are due to other complex reactions occurring. Most of you may have made fruit esters (like banana ester) in science at school. Esters are formed from a ‘carboxylic acid’ and another hydrocarbon (typically an alcohol in the case of wine). As the wine matures, the primary fruit diminishes and transforms. Some of the complex esters making up the fruit flavours and aromas change into different esters, and other new esters are formed. There are literally billions of ester possibilities, depending on the chemical conditions in the solution. So wine presents its own unique conditions and time, heat and oxygen give it the opportunity to change.
What’s so good about all these changes?
Generally, we mature wine to increase the complexity of flavour and aromas, and to make the texture in the mouth more agreeable. Provided the wine is sound, has plenty of flavour, tannin and the right acidity level, the changes that occur with time will be positive. You’ll see more interesting aromas and flavours, and the wine will become smoother and feel better in your mouth.
Young wine can still have a level of complexity about it, but can also be rather simplistic in terms of fruit flavour.
How long should I mature it for?
This is a tough question. How thirsty are you?! Maturing wine takes time, and a lot more wine is now made to drink younger. Through winemaking and viticultural practices, wines with lower acidity and less tannin can be produced. These wines may benefit from short to medium term cellaring (approximately 3-8 years), but are really made to drink straight away. More complex flavour and aromas may be produced, but the already reduced tannin and acid will prevent the wine from living on. If you want the benefits of wine maturation, you need to choose wines that can be matured.
We can’t tell how well a wine will mature, until it’s mature. We can only guess through past experiences. Generally, a wine with good tannin, acidity, flavour and texture has the potential to improve with maturation. But the next question is how mature is mature? This is an answer you need to work out for yourself. Then you need to factor in your storage conditions. Are your wines in an underground cellar, or quality wine storage fridge? Or are they stored on top of the fridge in your kitchen? Heat speeds up reactions, including wine maturation. Wine can also be affected by light, and not in a good way, so ensure your wine rack is in a cool dark place.
Hopefully you have more than one bottle of each wine you are maturing. If you open one and it still tastes young, you can keep the others for a longer period. Unfortunately, we can’t tell you how long it will take for the wine to look its best. Maybe as long as your piece of string?
There’s a reason people drink mature wine. It can have flavour, aromas and textures that are simply divine and can only be achieved with time. The texture can be silky smooth, the aroma intensely complex and the flavour can be so amazing you remember it for years after. Every wine critic, judge, journalist or enthusiast will have at least one defining wine moment they can recount to you. I can assure you it will not be a young, current release wine!
Maturing wine can be wonderfully rewarding, but you need to think about why you’re ageing wine (investment or improvement) and choose accordingly. Then don’t forget that the storage conditions and closure type are as important as the wine itself. And lastly, buy more than one bottle of a specific wine to mature! A six pack is good. You can open a bottle every three years or so and see how it’s developing. You can then start to get a picture in your own mind of how mature you like certain styles and what to buy for the future.
Ultimately wine is to be enjoyed. You can put as much effort into that enjoyment as you like!