Wine taste altered depending on bottle colour

Storing white wine in showy flint glass bottles could cause the wine to deteriorate, a new study published in PNAS suggests. Italian researchers tested over 1,000 bottles to see if the colour of the glass had any effect on the contents, simulating what happens before your drink hits the supermarkets. Here to explain the findings, Will Lowe the founder and master distiller of Cambridge Distillery. If you think 1,000 bottles of wine sounds like a lot to sample, Will has tasted over 10,000 in a year because he’s also a master of wine. The lucky Harry Lewis went to see him at work…

Will - Fundamentally, the idea of a bottle is to get the liquid to you, the consumer, in as close to the form and condition that the winemaker intended as physically possible. In many situations, that means that it should taste, feel, look, present exactly as it did when it left the winery, and in other situations, it can be quite different in the case of wines that are intended for maturation, for example. And then we have the secondary role, which is that these days, very importantly, the bottle is part of the self-marketing of that liquid. It's there to help sell it. So regardless of whether a wine may or may not improve within the bottle, if nobody buys it, no one would ever even know. And I think particularly in the case of rosé wines, it's become increasingly important that people are buying with their eyes. Without people being able to see that, that would be a very hard sell indeed.

Harry - So it actually does have an effect depending on what you bottle your wine in can influence the taste? How does it do that?

Will - This has been well known for many years; the first person to write about what's now known as light strike was written back in, I think, 1983. So what we're looking at here is two potential mechanisms of breaking down of flavour. Clearly, you have heat properties that can be exacerbated through light, but the real key that we're looking at here, and the one that's coming under some scrutiny, is the influence of UV light in particular on wine and the flavours therein. The flavours of wine, made up by both volatile, aromatic compounds (the things that you can smell), but also its physical characteristics, the alcohol and the acidity etc that are latent within the bottle. As a bottle of wine changes - and all wines under all conditions will always change as this is a dynamic biochemical environment that we're looking at - you can see an emergence of favourable or unfavourable aspects, as well as a reduction in both favourable and unfavourable. What we're looking at in this study specifically seems to be predominantly the deterioration of the favourable characteristics and in particular, those which are offering varietal typicality. So that flavour that makes a Sauvignon Blanc so easily identifiable, for example, appears to deteriorate under certain conditions with greater exposure to UV light.

Harry - Any excuse to have a midday drink, I've bought a couple of bottles along - two sauvignon blancs that I just got from the local supermarket. So again, I should probably really stress that this isn't a forte of mine. I do go for the lightest rosé though, but I just think it's because it's in trend.

Will - It's very Instagram friendly!

Harry - It is Instagram friendly. I wonder if perhaps we could taste one and then you might be able to describe what would happen if we were experiencing light strike, how that flavour would change.

——当然,会让我拿两杯水吗then... Now the theory has it that light strike would be most common in clearer glass. So in terms of filtering out that UV spectrum or close-to-UV spectrum that we want to avoid, green glasses slightly better, amber Glass is better than that, darker brown is even better yet. The harder it is to see through, the harder it is for the UV light to get through. You've very kindly brought two in here. One is a slightly light green colour, which we'll try first. And then the other one in as close to clear as you're likely to be able to find, I would imagine. Now, Sauvignon Blanc is famously most often produces a single varietal, meaning there's just one grape type in there, as opposed to, for example, in Bordeaux, where you'll find a combination of different grapes. For that reason, most often labeled varietally - so it'll say "Sauvignon Blanc" - and then, fairly common new world themes is that you'll have, as you've got here, a name of a random animal; we call them "critter wines". They're the cute naming after an animal is usually what sells them. What makes Sauvignon Blanc so identifiable to most people is it has this very distinctive aroma. Not everyone can smell that, there are genetic predispositions that will mean that you can't, but for those of us that can, it sits somewhere between gooseberry, fresh cut grass and passion fruit, I think would probably be the closest and easiest way to get to it. Gooseberry is most often used as the descriptor. That comes from a certain set of volatile aromatic compounds, which we are seeing through this paper are susceptible to this feature of light strike. I've not even tasted that, I've just nosed it, and this is part of building up a familiarity; you do get to a point where a quick nose of the glass is enough to help you with the varietal identification. If we pick up the second glass, to be honest, this is working better than I'd expected it to do. Certainly, you can still sense on the nose alone the aromatic profile that would lead you to Sauvignon Blanc, but it is muted, isn't it?

Harry - The clearer glass bottle is muted? It's not quite as punchy?

Will - Yes. If I were to use a fairly crass metaphor, I would say that the darker glass is turned up to eight out of 10 volume and the clear glass is maybe a three or a four. It's a marked difference. Now, all things are not equal here. These are from two different countries. It isn't a fair single variable assessment that we're making here, but that is demonstrably the case, that this does smell far more restrained. Let's be honest, that could also be winemaker intention. Some consumers will want a vastly more focused and aggressive style, and some people will want something that little bit more elegant and demure perhaps. But what we saw in this paper is that they ironed out that crinkle of winemaker intention by taking the same wines and treating them differently. So they were able to really isolate that as a single variable.

Harry - Let me jump to a big conclusion then that we definitely shouldn't do. If there was a take home message for other listeners, would it be stick to dark bottled wines?

Will - No, I think it's really important that we have this onward march of science to help explain things that are happening in our real world, help us to understand control and avoid them if necessary. But look, if you've been buying your white wines or rosé wines in clear glass for the past five years and you enjoy them and you're still buying them, then go for it. If, on one occasion you do get one that has a weird sort of uncharacteristic smell or flavour that you can't reconcile with your previous experience with it, then it's really useful at this point to understand it's probably due to an avoidable fault. That avoidable fault in that instance is probably not caught, it probably is affected by light strike.