Wine: How to use your nose

How important is the sense of smell to our experience of wines? We know that a large part of what we call taste is in fact due to smell. The tongue’s receptors only provide information about taste: sweet, sour, salt, bitter and umami. Wine critics will talk about notes of melon and pineapple in Chardonnay and the licorice and cherry character of Chianti, but we don’t have melon or pineapple, licorice or cherry receptors on our tongues. Our experience of fruit flavours is largely due to smell. Yet those fruity flavours are experienced as if coming from the tongue. Yet it is the brain that combines the taste, touch and smell, and fuses them into a single, unified experience of flavour. It is this integrated working of the brain that experts try to unpick, with only some success, when tasting professionally.

Although your sense of smell’s contribution to assessing wine on the palate is vitally important, it tends to go unnoticed. However, smell plays a dual role in tasting, and the interaction between these roles is intriguing. Consider what happens when you stick your nose in a wine glass. Assuming that it is not the smell of the glass you are getting, which can be the case with the dishwasher powders used in some restaurants, what you will get at first are the most volatile molecules: the ones that escape the inhibiting power of the alcohol. Very often, these will be fermentation aromas and you’ll have to swirl the glass before the more reticent aromas of fruit are released. When you attend to the second nose, what expectations do they set up about the wine’s flavour? It’s worth pausing next time and trying this out. Does the wine taste exactly as you expected? Very often the answer is no because there are features of the flavour that only the tongue can provide. Bitterness has no characteristic smell, nor does the saline taste that comes through in wines described as showing great minerality. So a key part of flavour cannot be detected by the nose alone. Another surprise is the level of acidity in a wine. On the nose we can judge a wine to be fruity, but, fruity is an odour and there can be fruity and sweet or fruity and tart; it is the contribution of taste that resolves which of these it is.

Another mistake is to think a wine smells sweet: sweet is a taste, not a smell. You can discover this for yourself by sniffing a vanilla pod. Most people will say it smells sweet, though it tastes extremely bitter. So what is going on? The answer is that we combine the vanilla aroma with things that are sweet to the tongue—ice cream or custard, for example—and the brain has learned to associate the aroma with the taste. However, this can mislead us when smelling an oak-matured wine. The whisky lactones from the barrels will provide the notes of vanilla but what follows may subvert the expectation of a sweeter wine. However, we know that the association western tasters have between vanilla and sweetness means that whatever we sample on the tongue, when preceded by vanilla aromas, will be perceived as sweeter than if we were sampling the liquid alone. This is the sweetness enhancement effect.

Finally, the use of smell is particularly important when visiting a winery. The first thing I notice is whether there is a harmonious smell in the cellar. Beware the wines that come from cellars with a tell-tale off note. However, you must equally avoid the lure of only tasting the wines in this environment. The aroma of the cellar, remnants of the pressed juice and fermentation tanks, can affect your experience of a wine. I always want to take the wine out of the cellar to see how it performs in open air.

The best wines will announce themselves from the moment the cork is pulled. They fill the glass with beautiful scents that make you want to go on sniffing almost without the need to taste.