How wine matures

Knowing when to open a bottle from your wine cellar is easier to judge if you know how the wine matures. Here we provide an understanding of how wine actually ages in the bottle – the chemical and physically process that take place. 

The maturation of a wine is a function of its composition, its origin and its vintage. No two bottles from the same Bordeaux chateau but of two different years will develop and mature in the same amount of time. The more you know of what goes into a wine and how it is made, the better you will understand how and why it ages.

Wine is aged in two ways; barrel ageing which is part of the production process, and bottle ageing, which some fine wine producers undertake themselves before marketing their products, and which is then taken over by the eventual owner of the wine – whilst the wine sits in the wine cellar.

No one knows for certain what happens during the ageing process. We do know that the wine undergoes an olfactive evolution. The nose a wine has when it is young is called its aromas, while after it is oak aged and mature these same odours become more complex and profound and are referred to as the bouquet.

During bottle ageing red wines depose little plaques and grains of colouring agents and other molecules, which bond and fall to the bottom of the bottle. The heavier clusters settle faster and sooner than the smaller ones, which need years to settle. As these colouring agents settle in the bottles, the intensity of the wine’s colour diminishes, becoming first more reddish brick and finally yellowish, as the anthocyanins, or colouring agents, in the tannins soften and diminish along with those tannins.

When we say that tannins ‘soften’ what is meant is that the wine has reached a point of balance in its development curve. The harsh edge is taken off it, and its texture is smoother and less drying.

In general, the maturing of wine involves four types of phenomena:

1. Chemical maturation includes the oxidation of the polyphenols, alcohol, sugars and organic acids; the conversion of alcohol into formaldehyde, acetate and ester; and finally, the hydrolysis of polysaccharides and glucose.

2. Physically there occur the insolubilization of salts, the release of gases, the evaporation of volatile substances and the dissolution of tannins.

3. Biologically we observe malolactic fermentation, which softens the malo acids, and a sort of fungus-like enzymatic change for those wines that were wood aged.

4. And finally there are physical-chemical changes, such as oxireduction, polymerization (the uniting of single molecules of the same substance to produce larger molecules, or mers) and the formation and flaking of colloids (substances that cannot crystallize and become solid, such as amidon and gelatine).

What is maturation?

Polymerization progresses continuously as the wine ages. Over long ageing tannic wines become gradually harder and more tannic, until they reach a peak where they are more tannic than they were in the barrel. Then the slope starts a gradual decline. The extra-large molecules lose their ability to combine with other proteins, and their astringency diminishes. At the same time they are combining with other components in the wine, becoming insoluble and precipitating to form the characteristic deposit. At this point the wine is in its mellow phase and is softer, richer and rounder: this is maturity.

If the wine is kept too long though, the increasingly large polymers gather strength once more – a sort of final wind – and become dry and astringent again. This is compounded by the fact that the wine is also losing its fruit and gaining volatile acidity. It is drying out, or dying. Knowing the moment at which to open a wine is a skill acquired, happily, through much practice! There do exist general guidelines based upon wine style and region – we’ll go through these in our article on vintages. But the best guide is to always have a test case of a wine on hand, and to follow its evolution yourself by tasting it periodically.

Certain wines reach maturity sooner than others, and not every wine has the same length of maturity. In general, the duration of a wine’s ideal maturation period is the length of time needed to reach it, and the better the vintage, the later the wine will mature and the longer it will remain at its peak. If a 1982 Latour or 1982 Gruaud-Larose reached its apogee in 1997, then you can hope to enjoy your bottles for fifteen years.

Letting a wine mature means waiting for all of its components to fall into balance with each other. Maturing will allow a wine to develop its own distinctive complexities, rather than express a varietal character; young wines do that. A good wine is one that is balanced and harmonious. Its acids, alcohols, tannins and fruits have all blended into one, creating a personality, a character. A less good wine will never fall into place, because its fruits will die; or its tannins will fade away into nothing instead of softening and holding the wine together; or its acids, the backbone and life of the wine, will become flabby or disappear. When tasting a young wine, look for all of these elements, to determine how well the wine was made and how it will mature. You can be rather certain of a young wine’s character, but you never really know whether that character will endure until you test it years later.

Do all wines improve with age?

No – almost 75% of wines produced today are meant to be consumed young. This is a problem for a couple of reasons. First, there is the fallacy that all French wines, and even all Bordeaux, merit long cellaring. The truth is that the majority of French wine styles are meant to be drunk two to three years after bottling. Second, more and more producers, as I have already discussed, are making even fine wines that drink better when young, in order to compete with the lesser-known, lighter-style wine regions )barrel and bottle ageing in the winery becomes an expensive luxury when your competitors get each vintage on the shelves before you’ve even finished vinifying), and to fit into the lifestyle of most wine consumers, who buy a bottle of wine to be drunk that same evening.

What is a great wine?

The magic trinity of soil, climate and grape variety but be considered the incontestable and objective determinant of a wine’s quality. It has been proven time and again that a particular grape variety, when married to a particular soil, in a particular climate, produces a unique and specific result. We do not know why, but there are some grapes, soils and climates that will never be able to produce a great wine, no matter what interventions man might offer to remedy the situation.

What amount of responsibility should the winemaker be given? Every step of winemaking, from planting the vines to bottling the wine, requires a decision that affects the quality of the outcome. It is no coincidence that wines born from those choices that are the most difficult and expensive to make are greater wines, and of greater value.

Extracted from ‘The home cellar guide’ by Linda Johnson-Bell.