The science of smell

When people sample whisky, it’s common to hear feedback like ‘wow, this tastes like chocolate, fruitcake, vanilla, toffee or even phrases like ‘fresh cut grass’ and ‘a summer’s breeze’.

But what do we actually mean when we describe what we taste? Scientifically we’re describing the general sensations detected by receptors on the surface of our tongue: sweet, sour, salty, bitter, umami (the savory trend word).

When someone says a whisky ‘tastes like chocolate’, they’re actually describing the overall flavor, referring to the perceptual experience we have when we eat and drink.

The idea of ‘taste’ being a base component of ‘flavor’ is well established in the scientific and gastronomic field, but recent studies are exploring other players that help create this experience - eyes, ears, lips and even hands.

In essence, we – due to our cultural background, chemical balance, genetics and positioning in time and space – have control of what we taste and experience. We are all tastemakers. This comes into play when we’re looking at the ‘designed’ flavor of a whisky compared to the real or even perceived flavor we experience.


Let’s start with the most commonly known contributor to ‘flavor’ – the nose.

The recognition of smell and the role our noses play in creating what we perceive to be flavor was discovered by Jean Brillat-Savarin, a gourmand of the eighteenth century.

Through his passion for eating and drinking, he explored and revealed the physiological and psychological processes responsible for the perception of taste in his book ‘The Physiology of Taste’. It explored the relationship between the nose and mouth, but it wasn’t until the late nineteenth century that Henry T. Fink in ‘The Gastronomic Value of Odors’ highlighted the different roles noses play in the creation of flavor when a person breathes in and out, which is understood to be ortho vs retral nasal perception.

Imagine you’re walking into a room and encounter a block of smelly cheese. You experience an overpowering smell of mold and ammonia; if you’re not a fan of the big boisterous blue you may recoil out of the room. You put a piece in your mouth, expecting the smell to mirror the taste, but instead you get an unexpected incredibly sweet, creamy flavor.

Ortho-nasal smell refers to what we’re breathing in through our nostrils – it evokes our sensations and sends signals to our gustatory system to begin producing digestive juices for what we’re about to indulge in. Retro nasal smell, however, is a ‘referred sensation’ – occurring when a sense appears to be in one place but actually arises from another, or a few combined.

Stimulated by the release of smell molecules from the ingested whisky, these smell molecules rush to the back of our mouths, up our nasopharynx and finally to our olfactory bulb, which sends signals to our olfactory epithelium, a special epithelial tissue inside the nasal cavity. This part of our olfactory system is directly responsible for detecting odors.

In recent years, two theories have discussed the way the receptor cells in our brain and nose ‘pick up’ and ‘fix’ onto certain odor molecules – size, through the ‘lock and key’ mechanism and vibrational theory, which was developed in the 1980s and popularised by Luca Turin, the perfumer.

The latter purports that different compounds have individual vibrational frequencies that bounce off our receptor cells and manipulate the message sent to our olfactory epithelium to conjure up different images of flavor.

So what happens next? How can this flavor be perceived if we smell the same liquid, yet experience it differently? Although our olfactory bulb is driven by stimulus properties, the representation in our olfactory cortex is memory-based.

With the ability to ‘learn’, the system can improve its performance with repeated exposure to different smells and match the input pattern of scents to stored patterns. Refinement, training and recognition strengthen the signal-to-noise ratio, or smell-to-memory ratio, allowing us to pinpoint certain scents melded together with others, and identify them as past memories. The more you smell, the more you’ll recognize smell and grow your vocabulary to describe whisky.

This article series above was originally presented at the WED talks: Whisky-inspired TED Talks at Tales of the Cocktail 2013.

While the process of hiring that we’ve just described sounds expensive, daunting, and time-intensive (and it in fact is all of these things), by establishing a company culture and benefits program that encourages high employee retention, we find that we only need to hire new staff infrequently. When it comes to hiring great employees, you definitely get what you pay for.

Georgie Bell

Georgie Bell is Diageo’s Luxury Global Malts Ambassador, with a specific focus on Mortlach. An established speaker, trainer and personality in the whisky industry, Georgie recently won the prestigious Worshipful Company of Distillers Award for a Diploma in Distillation.

Follow Georgie’s adventures on Twitter & Instagram @Belleswhisky