Wine spends most of its life in a bottle, yet it the ageing process represents a complex puzzle.
- Drink a wine too early and you get fresh primary fruit flavours – delicious but lacking integration of all the elements.
- Drink it too late and the fruit diminishes in intensity, leaving the wine dull and tired.
- Wines go through periods when they seem to withdraw and become quite closed.
- Wines made to age can be unpleasant to drink young as they require relatively high levels of acid and tannins for successful ageing.
Get the cellaring and ageing process right and the rewards can be fantastic. A wine at its peak can be memorable.
So what’s happening as a wine ages?
We all know from experience:
- Red wines lose colour; whites gain it.
- Powerful fruit flavours become more subtle and savoury.
- Acid and tannins fall away. The wine softens.
- Fruit aromas become more complex as bottle age characters inter-mingle with the slowly declining fruit character.
Wine is complex solution of alcohol, acids, phenolic and flavour compounds. It’s the chemical interaction of oxygen with polyphenols (tannins, colour pigments and flavour compounds), acids and alcohol in a wine that produce change over time.
Description of how a wine ages can be described in three different ways:
- The balance or weight between the components changes as they themselves change;
- A wine’s mouthfeel (front, mid and back palate) changes over time
- The individual components interact with each other over time.
Tannins & Colour
The phenolic elements in wine come from the grapes – anthocyanins (colour pigments) from the skins, and tannins (structure) from the skins, pips and stalks.
Over time a red wine will lose its brightness. Vibrant purple and crimson colours become garnet, perhaps with brown hues visible on the rim of a glass. A white wine first loses its greenish hue that marks it as very young. The bright straw colour increasingly turns golden.
Some of the phenolic chains become so large they eventually precipitate as sediment.
Acid and tannins act as a preservative, slowing oxidation and decelerating the flavour-changing reactions. Just as lemon juice keeps cut fruit from browning, acid in wines slows the oxidation process, which means that acidic wines are better candidates for long ageing.
Tannins have an astringent, somewhat bitter taste making your mouth feel dry. Over time, tannins “soften” because they polymerize forming long chains. As the tannin molecules lengthen, they feel and taste less harsh – the wine becomes smoother with age.
Generally white wines, being very low in tannins, are less commonly good candidates for ageing. But acidic varietals such as Semillon and Riesling are exceptions. Cooler, high altitude regions such as Tumbarumba generally produce white wines with higher acidity which improve its’ longevity.
Note too, that as a wine softens and as the balance between the different components changes (what we refer to as “structure”) and alcohol sometimes increases its prominence in a wine (tasted as increased “heat” on your back palate).
Vine yields also influence a wine’s longevity. A viticulturalist can manage vines and canopy to produce 10 tonnes to the acre or perhaps just 1 to 2 tonnes/acre. The vines and grape each compete for nutrition. A vine cannot bestow ten grape bunches with the same phenolic intensity and richness as it can five. And so with higher yields, the ratio of polyphenols to juice is reduced.
Vine age is a factor too. Young vines produce bigger grapes with more juice and thinner skins. Their roots are more shallow so they suck up more water. They produce grapes that tend to be less rich in phenolic components.
And as I said in my previous note (https://www.backvintage.com.au/blog/?p=251), oxygen affects the aroma and flavour of wine. The fruit flavours and nose of a young wine fade and combine with wood and alcohol notes to produce something that’s more savoury. Over time in a red you’ll get leathery, earthy notes whilst white wines develop nutty, yeast-like flavours.
Even the humble Winemaker has a significant impact on a wine’s longevity.
- The length and temperature of maceration (when seeds and skins of grapes are left in contact with juice or wine for a longer period of time), during which polyphenols are extracted from the grapes, influences tannins levels – a longer and hotter maceration extracts more tannins and more colour.
You’ll see these terms bandied around:
Cold Soaking – (typically 12 hours to 5 days) when extended maceration is used on unfermented grape juice. The cool temperatures keep the juice from fermenting whilst
the skins and seeds macerate in the liquid,
Extended Maceration – maceration is used after the grapes have undergone fermentation (anywhere between 3 and 100 days). Not only does extended maceration
increase the volume of tannins, it also causes tannin polymerisation, thereby softening the wine and reducing bitterness.
- Yeasts play a role as they can help to fix (ie prevent from changing) colour.
- Oak ageing, and particularly the amount of new oak used, is another strong determinant. Oak barrels add tannin, increasing a wine’s resistance to oxidation. The permeability of barrels enables oxygen to interact with the wine, encouraging the tannins and anthocyanins to combine. This combination process helps to stabilise a wine’s colour and structure.
- The amount of sulphur dioxide added to the wine makes a difference. Suphur Dioxide has an antioxidant and antiseptic effect thereby limiting oxidation and eliminating the bacteria that make wines unstable.
- Over filtration can reduce longevity by reducing solids in the wine.
Hopefully these notes help guide you through the wine “ageing process”.
And my Recommendation?
Find a wine you like. Buy a case.
Drink a bottle once every 3-6 months and write down your thoughts and tasting notes about the wine each time you drink it. (how to write tasting notes is another future blog).
You’ll soon notice subtle and more substantive changes to the wine over time.
And you can decide when the wine is at its best to drink !
Cheers and good luck,
BackVintage Wines Australia Pty Ltd 2018