Have you ever wondered why white wine varies in colour?
Some are almost water white, while others can be lemon though to golden amber. Surely there must be some logic to this?
Of course there is, but there are lots of inter-related factors which affect the colour of white wines. Let’s have a look at them one by one. Hold on to your hats, this might get a bit geeky by the end…
Oak Tree (credit: DannyBoy7783)
More specifically maturation in new(er) small(er) oak barrels adds colour. Certain types of wine are more likely to be barrel aged – Californian Chardonnays, for example – so much so, in fact, that you can see the difference before your nose gets anywhere near the glass.
See this post from 2014 for a more detailed discussion on oak.
Botritised Aszú Grape berries for Tokaji
The sweeter a wine is, the darker it will generally be. If you take a dessert wine (such as Hungary’s famous Tokaji) which comes in varying levels of sweetness, the depth of colour is a good guide to the level of residual sugar.
In fact, even on the basis of a mobile phone snap on twitter, I’ve had people make a good guess as to the number of Puttonyos* of a Tokaji – totes amazeballs, as the kids say nowadays.
(* putts for short, refers to the number of buckets of sweet grape paste added to a vat of fermenting wine)
As a general truism, red wine gets paler with age and white wines get darker. An illustration: the unique red and white wines of Chateau Musar in Lebanon move closer and closer in appearance as they mature in bottle. Even Champagne goes golden when mature.
If you’ve got a bottle of Marlborough Sauvignon Blanc that looks quite golden though a clear glass bottle, the chances are that it is past its best…
This factor is the one that most people would guess at. Some white grapes have a slightly darker juice than others which affects what you see in your glass. Good examples of this from my favoured region of Alsace are Gewurztraminer and Pinot Gris.
The Spanish region of Rueda is known for its excellent yet inexpensive whites made from the fairly clear Verdejo grape, but wines of the same vintage do vary in hue. This is down to a certain proportion of Viura in the blend, a permitted grape in Rueda and Rioja plus Catalonia under the name Macabeo. So there you go!
Oxygen is both the friend and the enemy of all wine, red, white and all the diverse colours in-between.
a) Oxidised – when exposed to too much oxygen white wines go darker in hue quite quickly. When it happens this can be known as premature oxidation, or premox for short, and has spoiled many a white Burgundy lover’s treasures.
b) Oxidative – this descriptor is used when a wine is deliberately exposed to oxygen, for example with traditional white Rioja. This style of wine will generally be darker than one in a non-oxidative style.
6. Skin contact
The biggest fundamental difference between red and white wines is not the colour of the juice when grapes are pressed – with some exceptions, the juice is normally clear. The difference in colour is down to the time that the juice for red wines has in contact with the skins so that colour, flavour and tannin is leached out.
A very short time gives a rosé, an extended period can give an opaque, dense looking wine.
If you use the red wine approach with white grapes you get….orange wine! This is actually a very ancient method of wine making that has become trendy again. It’s arguable that, rather than being a darker type of white wine, orange is actually its own class of wine by itself.
Bâton (the ones for stirring wine look a little different)
This is a fancy French term for stirring with a stick (which sounds somewhat less glamourous). After fermentation some styles of white wine are left to stand on their lees, i.e. the spent yeast cells which have turned sugar into alcohol. It is particularly useful in Burgundy where it gives a certain creaminess to Chardonnay.
Wines made with lees contact tend to be markedly paler than those fermented in stainless steel and then transferred to cask for barrel maturation because darker pigments are absorbed by the lees.
White wine colour is also affected by the wine’s levels of pH and the amount of acid (usually given as the equivalent in grams of tartaric acid for the chemists out there). Very simply, more acidity leads to paler white wines.
As part of the modern winemaking process, wines are usually filtered before bottling to remove any tiny particles which might give them a cloudy appearance. It depends on the substance used, but some such as charcoal will lighten a wine as tiny coloured particles (as well as some of the flavour) are removed.
Sulphur occurs naturally in wine, which is why pretty much every bottle in the shop has the caution “Contains Sulphites”. Sulphur Dioxide (SO2) is added as a preservative agent at different parts of the wine-making process, and in different amounts. There is a growing movements among artisan and “Natural” winemakers to reduce or even eliminate these additions.
Particularly in tandem with a low pH (i.e. high acidity), high SO2 concentration has a bleaching effect and removes colour from wine.
Of course, it’s difficult to see the effect in isolation as those producers who don’t add sulphur are often the same ones who allow skin contact…
Of course, these factors don’t act in isolation, and it might be several of them in concert which apply to a particular wine. For example, a traditional white Rioja is likely to be made from Viura, barrel matured and made in an oxidative style. Add a few years in the cellar then you will have quite an amber wine.
It’s not possible to point to any of these factors individually, but we can have a damned good guess!