Why does the world taste so different?

Part 1: Vive le difference!

As a Canadian living in the UK, I've been known to pour maple syrup on a full English breakfast. Bacon, sausages and baked beans are all greatly improved by the addition of the thick, sweet sap of my homeland, with its faint hints of woodiness and rich caramel overtones. For my English friends, this is nothing short of an assault on a national dish — dousing baked beans with syrup being the biggest cultural crime of all, it seems.

Around the world, there are plenty of examples of dishes that are acceptable to one culture but beyond the pale for most others — the tumour-like fungus that grows on corn (Mexico), developing bird embryos (Philippines), a giant rat (Togo), and jellied eels (UK) are all examples that come to mind. But our culinary differences are often more subtle than this, taking the form of preferences for tastes and textures that are the product of the culture we are each raised in — an affinity to sour tastes, for example, or a fondness for a creamy 'mouth feel'.

According to the International Dairy Federation, the average Dane ate 28.1kg of cheese in 2016 (Danish blue being a particular favourite). In contrast, the average person in China consumed 0.1kg of cheese that year (an amount I've been known to devour in one sitting). Genetics plays a part in how we each perceive taste sensations, but there's likely as much variation in sensory perception within a population as between cultures. This disparity in cheese consumption is not a reflection of differences in perception; Danish people are no less sensitive to perceiving pungent flavours than Chinese people. This dairy gap — like every difference in cultural taste — is a matter of preferences for particular tastes.

These taste preferences are first and foremost a product of our evolution. All humans, regardless of culture, favour salty and sweet tastes because over millennia they have offered vital nutritional — minerals and sugars, respectively. We're universally more wary of sour and bitter tastes because they can be an indication of foods that can make us sick. Yet if these preferences were hard-wired into our brains we'd be extremely limited in our diets and far less successful as a species.

Our dietary experiences as infants are also extremely important in shaping what foods we prefer. Dr Julie Mennella, a member of the Monell Chemical Senses Center in Philadelphia, has spent decades looking at how early sensory experiences with food shape our flavour and food preferences. Her research has shown that these experiences start even before we're born, as flavour molecules from our mother's diet find their way into the amniotic fluid and then later into her milk. These early flavour experiences teach us what foods our mother is eating, what foods she likes and what foods are available in the environment.

Mennella sums it up with a simple phrase: "You learn to like what you eat". And what we feed a child is determined by a complexity of social, cultural, geographical and economic factors.

Of course, learning doesn't stop in infancy; we continue to shape our food preferences based on learned experiences throughout life. A study conducted in the 1970s found that Indian labourers were particularly fond of sour foods, while Indian medical students weren't — the labourers enjoyed concentrations of citric acid and quinine that would make the rest of us pucker. Indian labourers live on a sparse diet (1,200 to 1,500 calories a day) that contains a lot of sour foods, including the sour tamarind fruit. Their partiality to sour tastes was because that was what was available to them on low incomes, and so they learned to love it.

Food isn't only a matter of taste, though — some cultures put emphasis on other aspects of the eating experience. Children raised in a Chinese culture, for example, are exposed to a far greater variety of food textures than British or American children. There is a plethora of words to describe 'gelatinous' and 'rubbery' in Chinese vocabulary. Having eaten sea cucumber, a delicacy throughout Asia, I can confirm that the fuss is clearly not about the flavour, but the rubber band-like consistency. In Mexico, the consensus is that food tastes better with a chemical irritant added; for example, chillies create a physical sensation in the mouth and trigger the release of endorphins (the body's natural painkiller). In Ethiopia, the aroma of coffee is particularly valued — the green beans are slowly roasted over an open fire and a host will pass the pan of roasting beans beneath a guests' noses periodically so that they can appreciate the developing aromas.

The globalisation of food and the large-scale migration of people are introducing new food traditions to the world. The general willingness to embrace the culinary successes (and flops) of other cultures is heart-warming in a world where the consequences of cultural divides make headlines daily. Yet, it's unlikely that our cultural differences around food will ever be reconciled completely. Food traditions are usually one of the last aspects of culture we're willing to relinquish. We learn new languages to facilitate communication, we embrace new traditions and experiment with new fashions in order to 'fit in'. Yet, there's nothing more comforting than the tastes of home. Maple syrup baked beans? Try them!

Doing things differently

Durian fruit: Flavour is a combination of taste and smell, and when it comes to smell, the durian fruit is headline news. Popular in Southeast Asia, this fruit has an intense aroma that many cultures find offensive, with descriptions ranging from body odour to raw sewage. It's often kept frozen when sold outside of Southeast Asia to avoid shoppers fleeing in horror.

Sweet biscuits: Familiarity with certain tastes can warp our perceptions of them. Sugar consumption in the US is 126.4g per person per year, whereas in Taiwan per capita consumption is 22.3g (2015; Euromonitor). When students from these two countries were asked to rate biscuits with different sugar levels, the Taiwanese students found the sweeter cookies that the US students loved to be rather unpleasant.

Wafer Oreos: The manufacturer of Oreos introduced a layered wafer version of the biscuit to China when sales of the original failed to take off. China now has many versions of the Oreo — from straw-shaped wafers to stacked wafers and green tea-flavoured cream fillings. Nicola Temple

Part 2: The science of taste

Flavour is key to our appreciation of food, yet most of us probably don't realise we experience it through a combination of both taste and smell — in fact, over 70% of what we experience as flavour comes from smell.

One of the foremost researchers in the field of taste, Professor Linda Bartoshuk of Florida University, explains: "When I pick up a strawberry the first thing I get is the wonderful aroma and smell; this is called orthonasal smell. Then I put it in my mouth and start chewing and compounds called volatiles are released. Chewing and swallowing forces the volatiles up behind my palate and into my nose; this is called the retronasal smell. Finally all these signals come together in your brain. They interact and that's the flavour. The flavours we experience are unique to us, they're subjective and we can't share them."

The taste buds on our tongue are blunt instruments; they can sense five basic tastes — sweet, sour, salt, bitter and umami (savoury). The subtleties all come from smell.

Chris Lukehurst is a director of The Marketing Clinic and an expert in food psychology, advising a range of high-profile clients, including Nestle and Unilever. He explains: "Think about it in terms of primary colours — yes the primaries are important, but we don't see the world in primary colours, we see it in a huge array of mixtures and hues, and all those differences come in fact from aroma."

Sight also plays its part, as it helps if food is attractive. Research shows that a red, well-formed strawberry will actually taste sweeter because of how it looks. This fact seems timely, given the boom in social media images of food, where visually appealing foods like cakes and melting cheese invariably draw the most 'likes'. Sight is what we begin with, and it sets up an expectation in the brain of what the food will taste like. Which explains why chefs place so much importance on presentation and plating.

Charles Spence, professor of Experimental Psychology at Oxford University and a leading expert in the field of flavour, says: "From the taste expectations we have in the brain, to the visuals, the crunching sound, the touch and the smell, all of those things come together to create flavour."

And that's not even the whole story — our emotions and behaviour also have a big part to play too. It's miraculous when you stop to think about it, and far more complex than most of us would ever imagine when we bite into a cake.

How flavour changes with age

As mentioned above, there is a general consensus that what our mother eats when we're in the womb has a direct bearing on the tastes we go on to like. Professor Jackie Blissett of Birmingham University, explains: "If the mother is consuming garlic when she's pregnant, we know that flavour passes into the amniotic fluid and babies continue to show preferences for those flavours later."

Similarly, a Mexican baby who might experience chillies in the womb would already be more used to those flavours when they're born, while an Indian child might be able to tolerate more spices. Research has also shown that babies whose mothers ate nuts while pregnant are less likely to develop a peanut allergy than those who ate none at all.

Children are born with an innate desire for sweet and fat and they have an aversion to bitter tastes. This is for evolutionary reasons; to ensure our survival with high-calorie foods when food was scarce, for them to grow faster, and to avoid bitter foods that might be poisonous.

Interestingly, children also have a fondness for umami — the savoury flavour present in foods like meat broth — as it's present in breast milk. Umami indicates high levels of protein, so it makes sense that children would seek this out too.

Children start by being conservative; they have more taste buds in their mouth than adults, and are super sensitive. Anything new is challenging and so most weaning starts with bland foods like pureed rice. However, they're also very influenced by their environment.

"A baby lying in a cot will also pick up aromas from around the house, and gradually learn to enjoy and tolerate those aromas. Children also build psychological associations with taste. Vanilla is a good example, as around the world it's associated with being homely and comforting. This is because mother's milk has a vanilla flavour to it and what makes you feel more secure than being fed by your mother? The same flavour is mimicked by bottled milk," explains Chris Lukehurst.

As children get older, new foods begin to be enjoyed, and the old saying that kids should try something 10 times before they reject it is largely true. Professor Charles Spence explains: "Familiarity breeds liking. However, you have to be careful as forcing a child to eat something over and over again may induce stress and the opposite result. In one experiment, scientists got children to play with vegetables and turn them into jewellery, and it turned out that stress-free exposure away from the dining table increased their familiarity and made them more likely to eat them."

Teenage behaviour around taste is similar to most of their other behaviour: a bit challenging. They're desperate to seem sophisticated and grown-up, so aspire to eat like adults and try bitter tastes like coffee and even alcohol. We're not born with a taste for bitter, but as we grow older we teach ourselves to like it, partly because some of these flavours contain rewards: like the caffeine in coffee, or the alcohol in wine. And the more teenagers try these foods the more they like them.

Chris Lukehurst says: "Anyone that has given up sugar in tea and coffee understands how we can train our taste buds. At first it's disgusting, but eventually you wonder how you ever liked it with added sugar."
Conversely teens may also start to reject healthy foods they used to like as a form of rebellion. They may be influenced by advertising and social media to try fast foods, and driven by whatever happens to be in fashion, whether that be pizza or pic 'n' mix. The current craze for bubble tea — a drink that originated in Taiwan and includes tea, milk, sugar and tapioca balls — has sucked in my 12-year-old daughter and her friends. It's so high in sugar that even bubble tea brand Bubbleology's own website recommends it as an 'occasional' treat'. Hormones may play a part here too — research has shown that girls may need a higher concentration of sugar in order to get the same hit as boys.

Adulthood and old age

Our senses peak in our 20s and we begin to appreciate more complex, robust flavours like goat's cheese, chilli and avocado. Our sense of taste, thereafter, remains relatively stable unless there is an illness or accident. We become less adaptable, however — studies have shown that immigrants over the age of 40 will usually stick to their native cuisine. Even so, for most people it's not until their 60s and 70s that they start to see taste and smell decline.
As adults, our food choices come to be part of our identity, as well as being an important element of social behaviour. We might choose to make healthier choices, or make choices for economic reasons. We're more experimental and excited to try new flavours and restaurants, and we are also influenced by our peers and travels to new countries.

However, experiences from childhood persist. If we vomited after eating a food, the memory and dislike of that food or drink can persist throughout our lives, which explains my lifelong aversion to clams.

Hormones may also make women more sensitive to smell — as any woman who's been pregnant will know — but differences between men and women are mostly small. Spence says: "It's possible women tend to be more affected by the smell of things than men; they go for different comfort foods too — choosing chocolate and ice cream, whereas men might go for savoury items like macaroni and cheese."

As people enter old age, their sense of smell and taste often begin to deteriorate. They may not notice if their taste buds decline, but smell is a different matter. "Losing a sense of smell has high indications with depression, as people don't realise how crucial smell is to food and flavour, relationships, and the things we enjoy in life," says Spence.

Professor Valerie Duffy of Connecticut University adds: "Because you smell through your mouth anything that impairs your ability to chew or move food in your mouth could impair the release of the receptors that grab onto the odours. In old age there are issues with teeth loss, or dentures or dry mouth and loss of saliva — all of these can impact on people's ability to sense flavour. Other causes might be frequent nasal or sinus infections or even a virus. Many old people are on medications and these may also impact an ability to taste."

As we get older our taste buds become less adept at regenerating. In Japan, trials are being conducted in which sounds like crunching and cracking are played to old people while they're eating. The aim is to use the sound to try and bring back their interest in food once they've lost their ability to detect much flavour. Other people use the senses of sight and touch to try to bring back the sensation of flavour and restore the lost loves of their youth. This is the case with Duncan Boak, who lost his sense of smell in 2005 as a result of a head injury and went on to found the charity Fifth Sense to help other sufferers.

"I focus more on my taste buds now and really hone in on those tastes of sweet, salty and bitter. Then there's the visual, the texture, the mouthfeel and the spiciness and when you start to focus on it there's a very broad palate of sensory inputs."

Foods we grow to like

Marmite: the salty umami flavour is pungent, and for many it's just too weird to spread on toast. However, once your taste buds are trained there's no going back. Marmite attracts fervent devotees who snap up the new 70g travel size so they can take it on holiday.

Chilli: This is not in fact a taste, but a pain signal sent by the nerves that transmit touch and temperature. The more you eat, the more you become desensitised and learning to tolerate hot spiciness is something we're prepared to do.

Feta: While some are put off by the saltiness, others who don't like feta recoil at the weird texture. However, a few holidays to Greece seems enough to cure most people's feta aversion.

Alcohol: Alcohol is a poisonous to our bodies but we teach ourselves to like it because it makes us feel good. The more we have the more we want, which can work against us. Overindulge in tequila, say, when you're young, and you may never touch it again. Laurel Ives

Share your culinary tales with us using #NGTFood.