‘Near enough to infinite’: How to invent a flavour​on January 18, 2025 at 6:00 pm

Bubblegum, beef, boysenberry. The shelves of Max Kleyn’s laboratory are lined with tiny bottles filled with big aromas. Sweet and fruity pineapple. Crisp and tart apple. Stewed Kakadu plum. If you’ve ever crunched into a choc-top ice-cream in a cinema, ate packet soup, or felt the tang of raspberry sherbet on your tongue, there’s every chance the flavour came from just a few drops of aroma chemicals like the ones in Kleyn’s lab.

Kleyn, an amiable man in a hair net and lab coat, unscrews a lid, and we grimace. “Cat food,” he laughs. His “catalogue” totals more than 1500 aromas, a few for pet food but most for humans, including for lollies from sherbet to gummy snakes. “Sometimes you get to work and the whole building smells like chocolate,” he says. Sometimes, “I’ve smelled like fish for a week.”

For Kleyn, a flavourist whose work has taken him from New Zealand to the Netherlands, then to Ballarat in regional Victoria, mixing chemical aromas is an art. “It’s a bit like working on a painting: you mix a lot of paints until you get the right colour. We know what each chemical does but not always how well it goes with another.” Kleyn can mix aromas to (more or less) reproduce almost any flavour in nature. “It’s all about perception,” he says. Or, as Gene Wilder’s Willy Wonka said of his Lickable Wallpaper: “The strawberries taste like strawberries, and the snozzberries taste like snozzberries.”

Unlike on a Wonka factory tour, though, there’s not a chocolate bar or gobstopper in sight, even if the bottled liquids tell our noses differently. Humans mostly detect flavour by smell; our tastebuds are in a related but different department of our senses. In fact, despite our insatiable appetite for information about culinary culture, the inner workings of cheffing, and the quest for flavour “sensations”, we don’t necessarily give much thought to where flavour comes from or how we taste. How is that we can tell the difference between a nutty caramel coffee, for example, and a fruity or floral one? Why are we drawn to some flavours more than others? Can certain music change the flavour of food? And could any of us, tinkering in our kitchens, create our own version of a snozzberry?

First, what’s the difference between taste and flavour?

They might seem interchangeable, but they’re not. There are, famously, five different types of taste receptors in a human mouth: sweet, sour, salty, bitter and umami. The latter, Japanese for “pleasant savoury taste”, was named in 1908 by chemist Kikunae Ikeda after he drank a soup made with edible kelp and found it had the chemical basis monosodium glutamate or MSG. (It was then popularised by food and biotech company Ajinomoto.) Some scientists now suggest there could be more basic tastes, such as for calcium or fat, although the jury is still out on this.

You might remember from high school the diagrams of a tongue divided into taste areas such as sweet, sour and bitter. “That’s absolute garbage,” says flavour chemist Heather Smyth from the University of Queensland. “It’s still in my daughter’s year 10 science book, which makes me mad.” In fact, our tastebuds – pink, mushroom-shaped structures called Fungiform papillae – each contains receptors for all five basic tastes, wherever they are on our tongue. There’s a concentration of them at the tip, a kind of early warning system to detect foul, rotten or otherwise sinister substances.

We encounter flavour, on the other hand, through a synthesis of textures, sights and even sounds that reach the brain as we eat and drink. “The meaty, the creamy, the herbal, the spicy, the fruity, the burnt is really flavour,” Charles Spence, an experimental psychologist who works with food, tells us from Oxford University. But it’s aroma that plays the biggest role. Scientists estimate it influences between 75 and 95 per cent of our experience of most foods.

Simply put, as we eat, some aromas waft into our nostrils to an olfactory system where sensory tissues behind the nose convert them into electrical signals to the brain. When we chew, we also push aromas to the back of our throat and up onto those same sensory tissues. Smelling via the nostrils is called orthonasal olfaction, whereas aromas we experience while chewing are retronasal olfaction. It’s no surprise, then, that some of the strongest-smelling foods have the most overwhelming flavours – truffles, blue cheese, durian fruit.

‘Put down some heavy cutlery, and it will immediately taste better. Play some classical music. Tell a joke before you serve it, as a mental palate cleanser.’

Appearance plays a role. When scientists colour pineapple-flavoured jelly with green and red alongside yellow, people generally report tasting lime, raspberry and pineapple due to a brain process called cross-modal perception. Chef Heston Blumenthal’s Fat Duck restaurant in Berkshire has pushed the concept further with a cross-modal switch: golden beetroot jelly served alongside a blood orange jelly, the orange colour tasting of beetroot and the purple colour of citrus. Diners take a moment to register the colours are incongruent.

“Most of the time,” says Spence, “we live in this world of our flavour expectations set by the orthonasal smell – from the sight, or maybe from the sound of the sizzle of a steak – and then only occasionally in real life do we check our actual flavour experience – taste, retronasal smell – and say, ‘Is that what my eyes told me it was going to be?’”

Sound can shape our flavour expectations, too. Spence won the satirical Ig Nobel Prize in 2008 for showing that people (really do) perceive potato crisps as tasting better when the crunch is louder. “What you’re hearing is dominating over what you’re feeling,” he says. Then there’s texture. Spence likes to play around with texture at his own dinner parties, using dimpled spoons or eating rabbit stew with cutlery handles wrapped in animal hair. “How often do you remember a stew?” Spence says. “It was emotionally impactful and striking.”

What other simple tricks can enhance flavour? “I think there are limits,” he says, “but put down some heavy cutlery, and it will immediately taste better. Play some classical music – cues of quality and class. Put it on an Instagrammable plate that makes an impression. And think about what to call it, don’t just serve it; give it a nice descriptive sensory label. Tell a joke before you serve it, as a mental palate cleanser.”

How do humans create flavours?

Back in the lab, Max Kleyn is overseeing a colleague as he adds drops of aroma chemicals to a beaker. At first, each chemical gives off a whiff of … something like paint, but when it’s diluted with a scentless “carrier” chemical, it comes into “focus”: we sip some from a shot glass and wave the mix under our noses. It’s syrupy sweet – and distinctly green apple. The company that runs the lab, Sensate, makes the apple flavour for anything from lollies to juices. A real apple is flavoured by at least dozens of chemicals, says Kleyn, but this solution is made of just nine raw chemicals, both synthetic and natural, the latter derived from actual plant components.

For us to smell something, it must start to evaporate. Chemical compounds that evaporate are “volatile.” A flavourist’s building blocks are a heady mix: compounds called esters form fruity aromas (the most volatile); aldehydes make heavier scents that add complexity; lactones create creamy notes (think coconut); and sharper notes come from ketones (aged cheese). “They all have their own little job in the flavour,” says Kleyn. “One gives you the mouth feel, the other one gives you more of the aroma. But they help each other as well.”

Although natural chemicals cost 25 to 30 per cent more to produce, many food manufacturers still use them to build a more complex flavour. Some opt for natural flavours because they believe it gives their product a competitive advantage, too. Food labelling standards don’t strictly outline how the word “natural” can be used, although consumer laws forbid labels being false, misleading or deceptive.

Synthetic flavours are never as complex as natural, says Heather Smyth. A synthetic version of vanilla’s main aroma, vanillin, will lack the compounds that make natural vanilla “more of a woody kind of vanilla, or a spicy kind of vanilla, or there might be a bit of a green note there as well”. Synthetics can help when the “real thing” isn’t available. Vanilla comes from the pods of a particular orchid. A shortage in Madagascar, which grows most of the world’s supply, is making it the world’s second-most expensive spice after saffron.

It’s not just industrial chemists who tantalise our olfactory systems. Farmers tweak flavour at the growing end. A mango from Australia tastes different from a mango from India or South East Asia. “We’re unique in the world in the flavour of our mango,” says Smyth. Even so, growers want to hone fruit and vegetable flavours to match what consumers like.

‘We grow things to a certain taste because we know which genes cause which flavours and which colours and which textures.’

The Kensington Pride mango, for example, is known for its sweetness but, in the 1980s, Australian growers cultivated a new offspring with less acidity and a longer shelf life called the R2E2 mango. “We grow things to a certain taste because we know which genes cause which flavours and which colours and which textures,” says Smyth. “We’ve helped the national papaya breeding program breed to select new red papaya varieties with improved consumer texture, colour and flavour.”

Away from the fields and labs, the kitchen is where most of us “make” flavours. Chef Adam Liaw’s seasonings align with the five tastes. “I guess in Western cooking terminology, seasoning tends to mean the addition of salt, but for me, it’s a much more holistic approach than that,” he tells us. “We can add sugar, we add a squeeze of lemon juice for sourness, we can add fermented ingredients, or you cook with wine or stock to get umami.”

Aroma is more particular. “Coriander smells like coriander. Mint smells like mint,” he says. “It’s not going to hugely affect the taste of your food, but what it will affect is the aroma.” Then he considers texture: whether he grates a carrot or roughly slices it, or whether he softens the vegetable in a pan or crisps it in an oven.

To Liaw, thinking of flavour as the sum of these parts makes variations seem “near enough to infinite”. He gives the example of a potato chip, a wedge, a french fry or a roast potato. “They are all combinations of potato, fat and salt,” he says. “People might change the texture of something, and then it becomes different. Or they might change the way it’s seasoned so it becomes different. If you’re talking about an aroma, there are probably hundreds of thousands, maybe even millions of particular aromas.”

Why do we like certain flavours (and hate others)?

“We like what we’re used to,” says psychologist John Prescott, author of Taste Matters: Why we like the foods we do. “It doesn’t matter where you’re brought up, you end up liking the food that’s in your culture. You know people, for example, who don’t eat oysters, you know people who don’t eat anchovies, but if they eat them for a little while, they get to like them.” It’s a process that starts even before we’re born. “The mother’s bloodstream carries the sort of flavour volatiles of what she’s eating, and they’re shared with the baby’s bloodstream.”

Coffee and alcohol are so-called acquired tastes. First, there’s the off-putting bitterness of coffee, the first coffee catch-ups with friends (and a few spoons of sugar), and before we know it, we have a short black to wake up. “In fact, these bitter-tasting things we’re not born liking,” says Spence. “But … we sort of get conditioned to.” Liaw points to a sticky-slimy texture in Japanese cooking known as neba-neba, found in fermented soybeans or seaweed, which can take some getting used to for the unaccustomed. “Fermented fish was not a big thing in modern Western cuisines. It was a big thing in ancient Western cuisines, and since the fall of the Roman Empire, it kind of went out of fashion.“ (In Iceland, fermented shark remains a traditional dish.)

‘Coriander tastes like soap for many people, due to a handful of particular genes.’

Then there are those emotional memories of food. One of the most delectable dishes Spence can recall were prawns slathered in mayonnaise, eaten from a plastic cup with family after his wedding in Colombia. “Plastic chairs, baking hot, sweaty – but just somehow fabulous,” he recalls. “If I took a little plastic cup of those prawn cocktails and ate it now, it would taste dreadful and of the 1970s or something.”

Likewise, negative experiences can “sour” our perception of flavours, says Heather Smyth. “I had a bad experience with spam – tinned ham – in my 20s. Today, if I even smell spam, I’ll be dry retching because I have a strong emotional memory that eating this is going to make me very sick.” Sometimes we’re truly predisposed to not like something: coriander tastes like soap for many people, due to a handful of particular genes.

Tapping into how we learn to like different flavours is where a great deal of the artistry lies. Sometimes, it’s a twist on a childhood memory (more on which in a moment) or a fusion that introduces something new, such as Korean tacos. Says Liaw: “We’re curious about food, and we want to try new things and adapt into new spaces, walk nomadically across continents and learn to eat foods as we travel. That’s an important instinct that we have, which is why we like new things.”

‘We have this evolutionary biological urge to want that balance, to want that variety.’

Then there’s biology. Our sense of taste is thought to have evolved to help humans eat a nutritious diet: sweetness helps identify carbohydrates, saltiness sodium, bitterness might indicate poisons, sourness whether fruit is ripe, and umami draws us to proteins. Infants’ tastebuds are particularly attuned: they have about 30,000, just a third of which remain into adulthood. Our multisensory perception of flavour has probably also developed with a similar aim, says Spence. “It would be sort of a difficult life if you had to stick everything in your mouth to figure out whether it was going to poison you or not,” he says. “It would be much easier if you had your eyes to figure out which trees to climb for the energy-dense fruits – the red fruits are generally riper, sweeter. You’ll save a lot of time. So the brain is sort of predicting because that’s much more efficient.”

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What people across cultures and personal preferences generally enjoy is balanced and varied flavours, including in a single mouthful. Liaw points to the trios of vegetables in many cuisines: the French mirepoix of carrot, onion and celery; the Cajun “Holy Trinity” of onions, peppers and celery; or the garlic, black pepper and coriander combination in many Thai dishes. “The reason we like these tastes is because there is a biological reason to like them,” says Liaw. “We have this evolutionary biological urge to want that balance, to want that variety.”

The same could go for salt and vinegar, for a sweet and sour lolly, or for the iconic Australian seasoning chicken salt (which contains no chicken but is packed with salt, paprika, onion, citric acid and garlic, among other ingredients). The “super complex” flavour of vanilla is an example, says Heather Smyth. “It’s a multidimensional experience. The best wines that we have are the most complex ones with the right balance of astringency and then those basic tastes – the tartness of the wine and the sweetness of the wine. We enjoy different flavours coming together.”

But can you invent a whole new flavour?

Max Kleyn once made a rainforest aroma – moist earth and leaves. “It didn’t go anywhere.” Flavours based on Australian botanics have shown more promise, such as Davidson’s Plum, native to tropical rainforests. Still, customers have tended to bypass other unusual flavours in favour of safer options. “Australia is quite old-fashioned still; it’s taking little baby steps,” he says. “People go back to the VB, the Heinekens and the simple stuff – more coffee. They try something, and it falls off again.”

Sometimes, chemists do strike on a flavour that eventually takes off. The kola nut, native to Africa, and coca leaf extract from South America were used in medicinal tonics in the 19th century, but the carbonated version was created by an Atlanta pharmacist in 1886 and popularised through marketing campaigns associating it with anything from Santa Claus (1930s) and polar bears (1990s) to the catchphrase “taste the feeling”. The salty, sweet British spread Marmite was made from yeast extract, a byproduct of brewing beer, which German chemist Justus von Liebig discovered in the late 19th century. (In Australia, chemist Cyril Callister created the saltier, yeastier Vegemite in 1923.)

‘Pineapple mania took hold in 1496 when Christopher Columbus presented one of the fruits to the king of Aragon, who declared it superior to all others.’

Outside the world of chemistry and food science, reckons Liaw, “There’s no chef that comes up with a new flavour … It’s taking ingredients, usually from another culture, and then using it in a different one.” Black pepper, used in South-East Asian and Indian cuisine since at least 2000 BC, was considered wonderfully exotic in places such as ancient Rome, where it was “bought by weight like gold or silver,” wrote historian Pliny the Elder. Pineapple “mania” took hold in 1496 when Christopher Columbus presented one of the fruits he’d collected from the Caribbean to the king of Aragon, who declared it superior “to all others”. “It’s described at the time as the most delicious taste imaginable,” says Spence. “We don’t think that today, so have our tastes changed or has the pineapple changed? Probably a bit of both, I think.” In the modern era, Spence points to Szechuan buttons that create a mouth-tingling sensation as something close to new – for him.

Novelty often comes from unlikely flavour combinations. At Gelato Messina, chef Donato Toce has been designing icy flavour combinations since 2009. His brief: “Go nuts.” Saffron and pistachio praline? “Didn’t sell”. Balsamic gelato? “Went into the bin, it was just wrong.” More successful: Nacho Libre, frozen avocado, tomato salsa and corn chips. And this: Parmesan and white chocolate, “which actually tastes like cheesecake, funnily enough”.

“For some people it’s nostalgic, sometimes it’s the words rather than the flavours,” Toce says. “We’ve got a flavour we call Triple Whammy, which is a Milo gelato with Oreo biscuits and Nutella. Saying those three flavours together, everyone knows exactly what it tastes like.” “Fairy bread” is another hit.

‘Low-frequency sounds make things taste more bitter; tinkling, high-pitched sounds make things taste sweeter.’

“Multisensory gastronomy” can also leverage nostalgia. Blumenthal’s celebrated Sound of the Sea dish – which includes tapioca to look like sand, foamed oyster juice and white soy sauce, with seaweed and shellfish sashimi – is served with a soundtrack of waves crashing and seagulls screeching. “It brings lots of people to tears,” says Spence, whose research into sound inspired it. (Spence met Blumenthal in 2003 and they have collaborated on several dishes over the years.)

“That led into more of what we’ve done since,” says Spence, “which is sonic seasoning, where we find you can use music to season food. In 2012, we figured out that low-frequency sounds make things taste more bitter; tinkling, high-pitched sounds make things taste sweeter. And so diners at a restaurant in North London had a sonic cake pop where on the menu it said, ‘Please dial this number with your phone if you want to bring out the sweetness for your dessert, dial a different number if you want to bring out the bitterness.’”

Lately, Spence has been considering a new frontier in flavour. “I know how to make things 10 per cent sweeter with sonic sweetness. I know how to make things sweeter with sweet smells, but it’s all within the known taste world. We are trying to work out how to make things that give you an extraordinary taste response,” he says. “We are trying to go beyond the basic taste world, figuring out whether we can make things that flip flavours, that are magical, and you don’t understand how this happened.”

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For now, even the most outlandish flavour concoctions are directly inspired by the real world, writes Raffi Khatchadourian in The New Yorker: “Whereas a perfumer can invent commercially successful aromas that are totally nonrepresentational – a Pollock in a crystal bottle – the flavourist must still respect the deeply held conservatism that people tend to hold when it comes to putting food in their mouths.”

Indeed, Liaw says we’re more inclined to try different flavours when we have an understanding of them – sashimi enjoyed in Japan for its freshness, coffee from parts of the world for different aromatics. “Cultural context, or natural context, is so important to food,” he says. “Food is not just fun to eat; our taste is a feature of how we interact with nature. And so to us, the idea of eating a completely unnatural food that has no connection to the environment whatsoever is an extremely foreign one.”

Still, given our food can be sourced, prepared and served in countless ways, we might be stepping out with flavour variations more often than we give ourselves credit for, Liaw says. “No one is going to stumble across the best-tasting flower in the world when they’re hiking in the Himalayas or anything. I don’t think the quest for great new flavours is out there somewhere; I think it’s within what we already have. Something as simple as spaghetti bolognese is made in 50 million different ways in 50 million different households around the world.”

For some fun summer reading, buy the new anthology from the Explainer desk at The Age and The Sydney Morning Herald. Why Do People Queue for Brunch? The Explainer Guide To Modern Mysteries is packed with astonishing facts and sizzling barbecue banter. In bookstores now.