Despite being a simple single lens system, the human eye is capable of distinguishing an incredible 2.8 million different colour variations. On a dark night it’s possible to see a candle flickering up to 30 miles away and if you look up to the sky you’ll be able to make out light emanating from galaxies up to 2.6 million light-years away. In comparison our hearing, smell and taste senses lag seriously behind the power of our optics. As commentators we spend countless hours attempting to define the aromas and flavours of whisky, usually drawing from a collection of less than 50 known smells and tastes, but the colour of whisky also plays a significant part of its overall visual appear. But, an examination of whisky colour can be much broader than just the hue of the liquid itself.
In this first of three short articles we’re going to be taking a look at where whisky gets its colour from, and the different between naturally occurring and man-made colour. In part two we’ll explore how brands use colour to build awareness, loyalty and positive product perceptions, and in our final part we’ll go a little esoteric and try to assess whether the actual aroma and taste of whisky can be equated to colours themselves.
From clear and translucent new-make spirit, through shades of young white wine and all the way to opaque treacle, the production of whisky inherently affects the colour of the liquid itself. Whilst new distillate has no perceptible hue, once the liquid is filled into a cask, a complex interaction takes place between the compounds in the wood, and the alcohol and water in the spirit.
Wood casks are packed full of tannins – the overall amount varying depending on the type of oak used – during ethanolysis (the process whereby ethanol degrades – otherwise known as maturation) the tannins and wood lignins are leached into the spirit and react with water producing gallic and polyphenol ellagic acids (from the tannins) and lyonresinol (from the lignin). The preparation of the cask itself also affects the compounds which interplay with the spirit – toasting and charring the inside of the cask before filling caramelises the natural sugars which are held in the wood cells. These not only provide pleasant toffee and caramel favours, but also give some brown hue to the liquid, as the coloured compounds are extracted from the wood by the spirit.
Different cask types provide both different colours as well as different concentrations of colour. They also do this at markedly different rates. A spirit maturing in an ex-bourbon cask may well develop into a light straw colour or, over time in to a rich and burnished gold, whereas a sherry or red wine cask will imbue a much darker amber hue to the liquid. Indeed, whiskies matured in port casks sometime take on deep ruby red or even salmon pink characteristics. The speed at which these colours leach into the spirit depends on a variety of factors – a first filling into a fresh sherry butt is going have a lot more natural sherried liquid contained within the wood to draw colour from than when the same cask is filled for a second, third of even fourth time. It’s important to note the influence of oxidisation on the colour of a spirit. Oxidation not only affects the overall flavour character of a whisky, but also its colour. Continued exposure to oxygen changes the chemical composition of many compounds within the liquid. Indeed in the case of sherry, an oxidised Pedro Ximenez is going to be naturally darker than a non-oxidised Fino.
This brings us on to a somewhat thorny issue – caramel colourant E150. The whisky industry has had a long relationship with E150 as an additive which helps them to ensure a consistent colour-profile. With many well-known brands producing large volumes of bottles, ensuring that consumers are offered a reliable and knowable colour to their whisky has been important to building up long-term brand recognition and success. Whilst single cask bottlings are drawn from one (or sometimes a few) individual barrels, the vast majority of bottlings are vattings of some description (sometimes involving large numbers of differing cask types). Consistency has been believed to be highly important to the brand propositions for these bottlings and it’s understandable – consumers would probably find it disconcerting to find large colour variances across what they believe to be identical bottlings. Many well-regarded whiskies still contain E150 colourant as a means to regularise production over time. Most whisky enthusiasts acknowledge this, but would largely rather let the natural colour of a whisky shine through as a preference. Their partialities are well served however, with a raft of bottlers choosing to not employ E150 nor the other identified production scourge – chill filtration.
Regardless of the chemistry or the production choices made, the colour of whisky inherently affects our conceptions, and indeed preconceptions of the liquid itself. We might look at a particularly dark treacle coloured bottling and expect notes of deep raisins, chocolate, leather – or all the other commonly associated sherry-matured flavours. But, likewise, this can lead to us down the road of pre-judgement. What if a very dark bottling doesn’t have these notes – what if the colour is not directly proportional to the flavour intensity we expect to find? If that a bad thing, and interesting thing or not a thing at all?
I’d highly recommend if you ever get the change organising or attending a truly blind tasting. And by this, I don’t mean a tasting where you don’t know the bottlings beforehand – I mean literally blindfolded. Relying on your sense of smell and taste alone is a fascinating experience in terms of judging a liquid purely on its flavour characteristics and not on its colour and the perceived influence that this may or may not have. Whilst this is a practical method for whisky tasting day-to-day, you would probably be amazed how much it can affect people’s assessment of what’s in the glass in front of them. A gold-coloured sherry bomb, a treacle-dark coloured bourbon-led experience – it’s all possible, just be careful that whilst assessing colour you don’t create too many presumptions and prejudices.