breaking news New

Tasting Irish Whiskey: The Science Of Taste

Pour yourself a glass of any Irish whiskey. If it’s at 40% abv, then it contains 40% pure and clear ethyl alcohol, and almost sixty percent tasteless water. The ‘almost’ is very important, however, for without it you would be drinking vodka, and you clearly are not. The spirit in your glass is not clear – it is a nutty amber colour; if you swish it around, it smells of all kinds of wonderful things that you can’t quite put a name to; also, unlike vodka, it tastes of something.

What you are experiencing here are the ‘congeners’ – the flavour elements, which in any decent whiskey only account for between 0.1% and 0.2% of what is in your glass. Put it this way: if you were throwing a party, and your bath was full of alcohol and water, then the flavour elements you would need to turn it magically into whiskey would fit into an eggcup. Congeners are simply the aromas and flavours produced during the making of spirits. Professional ‘noses’ have been able to identify 350 separate and individual congeners in whiskey. But there are well over a thousand, many of which are still unidentified. Some come from the barley, some from the distillation process and some from maturation.

A tasting

Pubs are great places to drink whiskey, but they are terrible places to taste the stuff. The air is too full of other smells – beer, floor polish and that guy in the corner eating crisps. Professional tastings take place in a sterile environment. No one wears perfume or deodorant; the glasses are rinsed to remove any soap deposits and left to drip-dry, lest they be tainted by a grubby tea-towel.

You don’t have to take it to this extreme, but if you are serious about it, it is best to taste whiskeys in a bright room where there are no strong odours.

You will need:

  1. A bottle of Irish whiskey, or, better still, grab a couple of bottles for comparison tasting.
  2. A jug and a glass of spring water. Tap water will do if you let it stand for half an hour or so, to allow any chlorine that may be present to disperse. The jug is for diluting, the glass for refreshing the palate.
  3. A glass or glasses for your whiskey. Forget tumblers – they were designed by the Americans for whiskey and soda, and are utterly useless for the job in hand. Professional tasters use a whiskey-nosing glass, but a sherry or, at a pinch, a wine glass will do. What you are looking for is a glass with a bowl to cradle and warm the whiskey in your hand, and tall, tapering sides to retain the aroma of the spirit.

Since we are in this for pleasure, let’s take the sensual rather than the analytic approach. We have to feed our senses:


Break the seal, pop that cork and pour. As the whiskey falls into the glass, you will hear the sound James Joyce described as ‘light music’. Joyce was so proud of sharing initials with John Jameson that he had his wallet engraved ‘JJ’, using the same typeface as the Bow Street distiller.


Forget about taste for a moment, and let’s have a little foreplay: hold your glass up to the light. What can your eyes tell you about a whiskey? A huge amount actually, which is why in ‘blind tastings’, where the whiskeys being tasted are anonymous, cobalt-blue glasses are used, lest the colour give anything away. For a start, your eyes can tell you the strength of the drink. Swirl the spirit around in the glass and look at its ‘legs’. These are the long trails left by the whiskey as it slips down the side of the glass. The longer the legs, the higher the alcoholic content.

Now, look carefully at the spirit, as not all whiskey is the same colour. Is the whiskey pale straw (American oak?), or amber (sherry wood?), or is it tinged with ruby (port pipe)? Colour can tell you a lot about the wood in which the whiskey was matured.


The nose is a very delicate instrument, and one of the most advanced and overlooked organs in the body. It is capable of detecting odours diluted to one part in a million; while there are only four primary tastes, there are thirty-two primary smells. The nose also plays a large part in detecting flavours, which is why when your nose is blocked, most foods taste bland. More often than not, when we talk about ‘taste’, we are largely talking about smell.

When you breathe in, air is rushed to the olfactory bulb, which sits at the back of the nostrils. From here, signals are transmitted to an area in the cerebral cortex called the hypothalamus, which, besides dealing with smell, handles emotional and sexual responses. The nose, then, is hardwired directly to the most primitive part of the brain, and this is why smells can be very evocative, even emotional.

Start by getting the ‘nose-feel’ for the whiskey. This is the prickle you get when you swirl the whiskey around in your glass and sniff. That tingle is alcohol; sniff again and it will anaesthetise your nose and you will smell nothing. If this happens, sniff a glass of water or go outside for a moment. Your nose grows accustomed to smells – after a while, a person can become used to just about any aroma. So it is important not to sniff too hard or too often – simply note your initial impressions and move on.

Now dilute the whiskey, and watch as eddies of water release the bouquet. Professional tasters nose at 20% abv – half whiskey, half water – but they also spit the stuff out. Do whatever feels best, but do add at least a drop of H2O, and your nose will be richly rewarded. With the addition of water, many of the keynotes you noted earlier will be more prevalent, but beware the noisy ones – peat, vanilla and sherry are first out, and tend to smother other, finer aromas. Note the obvious, then move on to tasting.


As well as detecting taste, the tongue is where ‘mouthfeel’ – the texture and smoothness of the whiskey – are experienced. What does the whiskey feel like in your mouth? Swirl it around – some whiskeys are fat and syrupy; others light and spirity.


Now pull in some air and the whiskey will come to life. What is up first – sweetness? Peat? Vanilla? A good whiskey will set off a chain of reactions on your tongue, sparking sensations all over, sometimes all at once, sometimes in sequence. Taste is registered by receptors – the taste buds – located on the surface and sides of the tongue. Those at the tip of the tongue transmit sweetness, whereas saltiness and sourness are transmitted from the sides.

Finally, swallow. What is the residual taste? Is it pleasant? How long does it last? This is called the ‘finish’. A poor whiskey will be gone as soon as it slides down your throat; a good one will rumble on for some time.

 Putting words to taste

Over the past couple of years, there has been an explosion of bloggers whose tasting notes may leave you wondering why you can’t smell ‘woody muscle’ or ‘hot cross buns’. These word-sketches are, of course, subjective, and just because somebody can smell ‘sherry-maltiness’ doesn’t mean you will – in fact, it doesn’t mean it even exists. Everybody’s sense of smell is different and, to complicate things further, we don’t all describe the same smell the same way. If we all liked exactly the same things, just think how dull the world would be.

Irish whiskey tasting wheel

This stylised wheel is designed to illustrate how the production and maturation processes affect the overall taste of Irish whiskey. In the centre are objective terms, and on the outer rim more subjective terms, which can be used when describing a whiskey.

Mouthfeel: Not a taste in itself, but a taste attribute, this sensation is largely influenced by maturation. ‘Viscous’, ‘thin’ and ‘round’ are just some of the adjectives commonly used to describe this tactile experience.

Phenolic: Phenols are the hydroxyl derivatives of aromatic hydrocarbons. In other words, this term refers to the ‘peaty’ or ‘phenolic’ nose found in whiskeys where the malted barley has been dried over a peat fire.

Feinty: ‘Feints’ are the rather oily-tasting compounds which come over later in the distillation. Although less desirable than pure alcohols, small fractions can contribute a lot to a whiskey’s character. These days, less feints are taken than in times past – this and triple-distillation mean that feinty notes in Irish whiskey are very rare.

Cereal: Barley, particularly the unmalted variety, leaves its cereal imprint on most Irish whiskeys, particularly those with a high pot-still whiskey content. Grain whiskeys produced from maize in a continuous still are milder and have less cereal character.

Aldehydic: When higher alcohols come in contact with the air during distillation in the pot still, each alcohol gives rise to its own aldehyde. These chemicals are mysterious in origin, but the aldehydes created from a wash of unmalted barley give Irish pot still whiskey its signature crackle.

Estery: Distillation not only produces alcohols, but also a range of other compounds, such as acids and esters. The latter are formed by the reaction between alcohols and acids and, since any acid can react with any alcohol, it is clear that this is where the unique ‘nose’ of many a whiskey is actually born. For example, amyl acetate, which is produced when amyl alcohol reacts with acetic acid, is the smell of pear drops; octyl acetate is the smell of oranges, while methyl butyrate gives you pineapples.

Winey: These are compounds acquired from the previous contents of the cask, such as sherry, port or Madeira. New whiskey is clear at first. It will take all of its colour, and perhaps fifty percent of its flavour, from the cask.

Oily: Nutty or oily flavours, which usually derive from oak lactones leached out during maturation.

Wood extractives: During its time in the cask, maturing whiskey reacts with the oak. Flavour elements are added from the wood, like vanilla notes and some tannins.

Musty: Found only in very old whiskeys that have spent a long time in a damp, dark warehouse. Nowadays, whiskey warehouses are invariably large, dry, airy structures.

By Peter Mulryan




The Whiskeys of Ireland by Peter Mulryan (Published by The O’Brien Press) is available in all good bookstores and online. RRP €19.99


Welcome! Login in to your account

Remember me Lost your password?

Lost Password