Why Do We Love Stinky Drinks?
The fragrance of farms, a suggestion of soot, or even a pipette of petrol. These are just a small selection of favourably foul flavours in whisky, wine, and other sensory stimulating swigs and snifters. Some have even been bounded into their own trending pigeonhole of mustiness – rancio. Our love of disgust is much wider though. How about that tonic in your gin, the barnyard in your burgundy, or the wood glue in your rum?
Evolution would have us gag, wretch, or turn a nose up at the pongs and wrongs of flavour. In fact, our very existence has been built on recoiling from things that taste bitter, rotten or simply noxious. Poisonous and deleterious edibles are conveniently awful on the palate. Surely it should baffle our very DNA that a little stink and bitterness could be appealing?
So what’s going on? Why have we become purposeful pursuers of pong, revellers of rank, and aficionados of filth? With nose pegs at the ready, join me for a distasteful journey into one of the most curious conundrums of sensory science.
Bitter Safe Than Sorry
Evolution has equipped us with some smart hardware. Our visual system is adept at recognising things that are most important, such as familiar faces, calorie-rich food, and special offers on supermarket shelves. Our peripheral vision has even become extremely sensitive at detecting subtle movements that could signal a predator.
Our sniffing hardware is a skilled system that specialises in separating the painful from the pleasurable, and the deadly from the desirable. It represents the first checkpoint before anything enters the mouth. It’s in the mouth that our taste receptors check for tell-tale bitterness and gone-off sourness. It’s here that we really begin to see how finely tuned we are at detecting poisons or harmful eatables.
Bitterness requires a large family of receptors called T2R, of which there are at least 25 members in humans. In contrast we have just two members in the sweet receptor family. Each one of or T2R receptors handles a different range of bitter compounds. However, it’s the T2R10, T2R14, and T2R46 receptors that have the busiest workloads. These three are responsible for detecting around half of all the 104 diverse bitter-tasting chemicals.
For the espresso enthusiasts out there, T2R7 is your crusader for caffeine. While the hoppy IPA beer fans will have a close relationship with their T2R1 receptors. The human genome also has many relics of old bitter receptors that are no longer in use. But why am I going into so much detail about bitterness?
The fact that we have such a highly specialised team of bitter receptors at our disposal highlights how seriously evolution takes not poisoning oneself. In fact, we are vastly more adept at detecting bitterness than any other taste. This makes our love affair with red-alert-flavours ever more remarkable and nonsensical. But how about aromas?
It turns out that even our olfactory system i.e. our sense of smell, is programmed to hunt the funk too. Boesveldt et al (2010) showed that unpleasant food odour was detected faster and more accurately than more pleasant food odours. Their research suggested that the olfactory system is predisposed to prioritise potential dangers based on their odour.
It is therefore clear that we are optimised for detecting things that are bad and ugly above those that are good and beautiful. Our ability to detect dangers by smell and taste alone outperforms our ability to detect nice flavours by some way. To understand the full depth of this chasm of a conundrum, let’s see how far-reaching it really is.
Seeking the Reek
Some of the most highly praised flavours stand on the shoulders of disgust. Like a spell of bad smell, we become so enchanted with the omnibus experience that we rarely question the hows and whys of bitter, rancid, or marvellously minging subcomponents. We’ve already touched on a few such as coffee, IPA beer, and barnyard burgundy. But there are many more.
How about those stinky cheeses, or even goat’s cheese with its famously goaty aroma. Many cheeses also dance on the bitter end of the spectrum, especially those of the blue variety. What does our DNA think about us eating mould for nothing more than hedonic pleasure? The more bizarre example, however, is perhaps parmesan with its distinctive butyric acid odour that’s reminiscent of vomit!
The wine world is a melting pot of foul flavours too. One example even exploits a marketing oxymoron, a New Zealand sauvignon blanc called Cats Pee on a Gooseberry Bush! The amusing point is that it would take a keen horticulturist and cat advocate to testify to its exactitude. For all others, we can only imagine!
In the old world of vinification one of the most curious notes, and indeed one of my favourites, can sometimes be found in riesling wines. TDN (1,1,6,-trimethyl-1,2-dihydronapthalene) is responsible for a characteristic petrochemical/paraffin note that sounds awful out of context but is delicious in context. It’s also a note that pops up in whisky from time to time too.
Speaking of whisky, the fermentation, distillation, and maturation concatenation of whisky presents a veritable wonderland of ghastliness. Rotting vegetables, bad eggs, wood varnish, damp fur, leaf mulch, nail varnish remover, and manure can all arrive packaged within a Tupperware container. While many will be removed or modified via various mechanisms such as condensers, cut points and maturation, some slip through, either intentionally or unintentionally.
Irritants play a big role in many foods and also drinks. Did chilli plants develop capsaicin because they wanted to say, “Eat me”? The same could be said for ginger, horseradish, and peppercorns. Of course, one of the most popular irritants is ethanol alcohol. Yet there’s something oddly enjoyable about the tingly sensation that these sensory assaults deliver, even though it flies in the face of evolutionary sense. One of the biggest challenges of the no-and-low movement is to explicate the complex mouthfeel that ethanol brings.
For whisky, we’ve only just scratched the surface. Mucky engine grease, chimney soot, stinky socks, sweaty horse, freshly cut grass, brine, charred grill tray, fish skins, thick tar... the list goes on. Does anyone actually want to drink this stuff?
Well actually the answer is yes. Just speak to any Campbeltown fan about ‘grime’. It’s all about the context.
A Spoonful of Sugar
It would seem that even Mary Poppins possessed some sensory science insights. A spoonful of sugar does indeed help the medicine to go down because sugary carbohydrates have a suppressive effect on both bitterness and sourness (Green et al, 2010). Fats and tannins have a similar relationship.
Tannic acid is face-scrunchingly bitter. Eat a handful of grape seeds to see for yourself. But as it turns out, tannins bind to proteins which lessens their assertiveness. This is why we commonly put milk in our tea, cream in our coffee, and drink red wine with meat. It’s also why milk chocolate is less challenging than a 90% cocoa solid suffering.
It will sound obvious, but our love of bad taste is largely dependent on balance. A sprinkle of sulphur adds body. A touch of tannins add structure. And a squeeze of lime juice brings flavours alive. The slightly wafty nature of terms like body and structure alludes to the slippery enterprise of verbalising sensations. But this still does not answer the big ‘why’ of our love affair with horribleness. To get closer, we need to go deeper.
An Acquired Taste
We often refer to challenging flavours as ‘an acquired taste’, but it’s actually a remarkably insightful statement. The notion that we can acquire a liking for something indicates an ability to stick two fingers up at evolution, but it also points towards the transient nature of flavour preferences.
It’s common knowledge that children are born with a preference for sweet and fatty tastes. It certainly makes sense to seek calorie and protein rich food during periods of rapid physical growth, whilst also avoiding bitter poisons at the same time. As we grow older, we generally shift towards more diverse flavours, including spices and bitterness. Is there anyone who actually enjoyed their first beer?
This could be partly explained by the degenerative nature of our sensory processes i.e. taste and smell sensitivity diminishes with age. It takes a while though so it doesn’t explain the change from adolescence. However, some interesting discoveries have been made when looking at the genes responsible for detecting the bitter chemical - 6-n-Propylthiouracil or PROP for short.
As it turns out, the receptor in question, TAS2R38, appears to change its sensitivity between adolescence and adulthood. This receptor is more sensitive in children than it is in adults to PROP, despite situations where no genetic changes have occurred (Mennella, Pepino, Reed (2005)). So certainly, in this instance our thresholds for some bitter compounds increase with age. But exposure also plays an important role.
Moskowitz et al (1975), found that Indian labourers who were exposed to high levels of tamarind in their diet, a sour and bitter fruit, reported a higher preference for quinine and citric acid. This was in comparison to a control group from the same region who consumed a different diet. Therefore, cultural context and exposure appear to play a significant role in how our sensitivity towards seemingly unpleasant flavours develops.
I can draw on another example from personal experience during the Naadam festival, Mongolia’s centuries old games festival. The traditional drink of the festival is airag, which is fermented horse milk shared between friends in the Mongolian equivalent of a quaich. This delicacy was certainly an ‘acquired taste’ from my perspective and had the character of alcoholic sour milk, as expected. To truly enhance the sourness, it was often accompanied by chewy chunks of sour horse milk too!
The point is that one person’s ‘acquired taste’ is very often another person’s delicacy and delight. Hence our associations with bitter and sour tastes may not be as DNA derived as we may think. I’m sure that many people reading this will have their own examples of local delicacies that challenge common western norms. It’s rather fascinating, is it not?
The Consumer Complex
There was once a time when we relied heavily on our senses to stay alive. Not in the sense of safely driving to work and negotiating the coffee machine, rather making everyday decisions about which foods could kill us and which ones could sustain us. We were forced into making decisions of life and death.
In the modern era we happily trust others with this responsibility. If something is sold wrapped in a package, we naturally assume it is safe to consume. As long as the sell-by-date gives us the all-clear. Non-perishable products such as whisky are rarely given a second thought with regards to their risk status. The only risks being the abv or personal bank balance.
This is purely conjecture I admit, but could it be that we have been neurologically desensitised to consumption risk? Could it be that we place so much trust in the producer that we do not even consider the poison/pleasure matrix? In fact, many poisons are consumed despite the knowledge of their harm. Perhaps this sense of trust has opened neurological gateways that allow us to enjoy flavours that were once off-limit.
In terms of whisky, for example, removing the question of “Is this safe to drink” could enable us to tone-down the disgust circuits and appreciate certain elements of stink. The mind is powerful enough to create a nauseating feeling by simply recalling a fowl flavour experience. Is it also powerful enough to make filth and bitterness more appealing if it feels safe?
Urban Overwhelm
Sensory stimuli are changing at an exponential rate. Whereas once upon a time new technologies were adopted on a more gradual basis, we now receive a significant update to something or other each week. Scientists have even discovered that the brain has developed a new pattern of brain waves that are unique to texting on a phone or tablet.
An entire industry has emerged based around getting people’s attention. So competitive is it that we now find ourselves bombarded with stimuli, be they emails, text messages, adverts, memes, billboards, or magazines. A simple walk to the shops can result in a mind-boggling amount of information for the non-conscious mind to process. (And here’s me adding to the problem!)
The point is that our senses are stimulated on a level of intensity that has not been seen prior. It would not be ridiculous to suggest that we seek increasingly intense and complex flavours in order to cut through the ‘sensory background noise’. At least to some degree anyway. While such an idea may be purely supposition, research has shown how urban air pollution can actually damage the olfactory system.
A review by Ajmani et al (2016))suggested how air pollutants can be deposited in the olfactory epithelium, the olfactory bulb, and the olfactory cortex. At each location they can cause direct damage to the tissue, inducing local inflammation and cellular stress responses. Studies have shown that air pollution is responsible for reduced olfactory sensitivity, along with the other primary senses associated with flavour.
An overwhelmed or damaged sensory system may in part offer insight into why we should seek increasingly intense flavours, and in doing so offer insight into the popularity of heavily peated whiskies and big sherry cask bruisers. However, it does little towards explaining the appeal of ghastly flavours.
To get closer to the answer we must next follow our noses towards the rise of the homemade, handmade, and handcrafted expansion of craft products.
Crafting Quirkiness
The rise and popularity of ‘craft’ shines a fascinating spotlight on the question of unusually tasty things. Whether its craft beer, craft spirits, craft food, or wine fermented inside concrete eggs! The artisan nature of ‘craft’ has become associated with alternative and idiosyncratic sensory experiences. Natural wine, uncommon yeasts, and heritage barley varieties are just a few examples of a quest for something ‘different’.
Many of us live in a privileged position where we have access to flavours and experiences that would have once been unimaginable. Merge with this our dopamine-based consumerist drive for ‘wanting’ and we can understand the desire for new sensory experiences that craft products seem to specialise in. We don’t need to look far to behold a carousel of entrancing cask finishes and small-batch bewitchment.
It's a component of the flavour industry that has certainly gained momentum in recent times. It’s exciting to discover new nuances, additional layers, and challenging characters. And while everyone will have their favourites, most also pursue a desire to explore. It’s a side of flavour that veers into sensory thrill-seeking. Certainly, links have been found between those who demonstrate thrill-seeking personality traits and those who pursue complex, extreme, and unusual flavours.
In simple terms we love a variety flavours. Dining out would not be the same if one were to have three identical courses, one after another. Instead, we may have a starter, a main, and a dessert. Or even a simple coffee. It’s the diversity and counterbalancing of flavours between each course, and even within each course, that makes the experience more stimulating - the novelty effect. It’s such diversity that introduces what may be the most valid point yet.
Filthy Flavours Are Exciting
If we consider some of the most interesting flavour combinations, or even some of the most loved ones, they follow a certain theme. Salt and toffee, port and blue cheese, lime juice and avocado, prosciutto and melon, cheddar and pickle, amaretto sours, even the classic bacon, brie and cranberry sandwich. They all create balance and fascination by combining opposing tastes, aromas and textures. Who doesn’t love a little vinegar or brown sauce on their chips?
Juxtapositions of flavour make things more interesting to our brains. If we consider the situations in which stinky notes are a benefit, we realise that they are balanced by opposing characters. In whiskies, a dollop of filthy engine grease is delightful when paired with sweet toffee. Creaminess and seaweed have wonderful charm. And who would have thought that manure would be so welcome within a hospital?
We also get excited by textures that change as we eat. Consider how the crunch of a crème brûlée becomes dismantled in the mouth. Or the audible crack as your teeth break through the chocolate crust of a choc ice. How about baked alaska, cheesecake, or soup with croutons? This is even before we consider the sensory wizardry that is put to powerful use in confectionary creations.
As it would seem, it all comes back to the common-sense themes of expectations and balance. Flavours active molecules work in either a synergistic manner or in a masking manner - meaning they either create something greater than the sum of the parts, or one dominates over others. It’s finding the balance that will determine when a flavour is beneficial or when it’s a fault.
When is a Flaw a Fault?
Thresholds are a key part of the story. Due to genetic variations and personal exposures, we each have different thresholds for specific aromas. Some people are very sensitive to sulphur, whereas others are not. Some people are bowled over by whisky lactones, whilst others are left guessing.
Such variation creates markedly different experiences of the same molecules in the glass. What may seem like just a tickle of farmyard for a distiller, may be overwhelming for others. Which raises the question of when is a flaw a fault? Who decides when blue cheese in a whisky is terrible or wonderful?
Many of the flavours we have addressed today will be considered by some as being ‘off-notes’. It’s easy to see how sulphur, farmyards and damp leaves may seem a little peculiar in a new make. But to others they are prized and celebrated additions. Even TDN, that pinch of petrol in your riesling, is considered a fault by some experts.
Peering Behind The Curtain Of Flavour
As with anything that peeks behind the curtains of flavour, topics can get very complex, very quickly. The one thing we know for certain is that there is an awful lot we don’t know. Why we should enjoy bitter and off-putting flavours is one of those mysteries. But, as we have seen, there are some things we do know.
We are designed to detect ‘off-notes’ faster and more accurately than traditionally pleasant tastes and aromas.
Our desire for certain flavours changes during adolescence. At least one of our bitter receptors in the mouth becomes less sensitive, meaning that bitter tastes become less horrible with age.
Access to world foods broadens our horizons and excites us to explore increasingly diverse and unusual flavours. This exposure helps us to accept flavours that may have previously been too bitter or off-putting.
Flavour molecules can be competitive, cooperative, destructive and creative. As to whether we enjoy the experience or not will be largely determined by balance.
We each have different thresholds and exposures to tastes and smells. What may be off-putting for one person may hardly register for another.
Our brains get excited by complex flavours that offer variety and juxtapositions within the glass or on the plate.
It’s the final point here that is perhaps the most poignant. A little sprinkle of stink, a few flecks of filth, or even a bit of burning bite can make flavours all the more interesting. Especially when we feel safe in the knowledge that the drink in your glass is safe to sip. Or so we’re told!
Those long enough in the whisky tasting tooth may remember a release from The Scotch Malt Whisky Society - Whisky-Flavoured Condoms & Skunk Road-Kill - which was exactly like is said on the bottle. While it certainly was not everyone’s cup-of-tea, one thing’s for sure - someone enjoyed it enough to bottle it!
It’s such diversity that makes flavours remarkable, memorable, and at times unconventional. Every dram, goblet, or flute is an opportunity to explore one’s own senses. It may not be where you want to go, but it will be an adventure, nonetheless.
Want to peek further behind the scenes of flavour? Check out our online tasting course for whisky enthusiasts and professionals: Learn The Sensory Science of Professional Whisky Tasting.