The science of your sweet tooth

Editor’s note: Every month we bring to you an article from our partner enthucutlet—a truly unique food magazine that brings you unusual stories, perspectives, and guides on food in India and beyond. The magazine is helmed by a brilliant team of editors and the good folks of Hunger Inc—the parent company of The Bombay Canteen, O Pedro, Bombay Sweet Shop and Veronica’s. 

This month, Madhushree Kamak looks closely at our perception of flavour—specifically the almost universal love for meetha—and what explains it.

Written by: Madhushree Kamak is a maverick scientist, illustrator and information experience designer who is the Programme Manager at Science Gallery Bengaluru.

Over to Madhushree…

Where does the sensation of sweetness come from? Our mouths? Our memories? Or is it all in our minds? 

The house is dark and quiet. Light is filtering out from the open fridge door, casting a dim glow in the kitchen. The cool air from the fridge melts into the night. Bent in front of the fridge, my hands move aside innumerable leftovers searching. Searching for something sweet.

Most of us have been caught by a sudden craving for this something sweet. Sometimes it comes when we are sad—take the familiar movie trope of broken hearted people eating ice-cream; or when we are tired or frustrated. Sometimes it emerges when we are excited and want to celebrate. In many human cultures, desserts are tied with the event of something fulfilled, of something achieved.

For us humans, sweets are also associated with rewards. Doing well on an exam, marking a birthday or a wedding—all of this is marked with a sweet in some form. From traditional Payesh to multi-tiered cake—sweets are also given as gifts. Chocolate bars, firm barfis—as apologies or declarations of love.

The craving for something sweet, the presence of sweets and sugar during milestones is natural because sugar can elevate our mood. The outcome of eating something sweet and sugary, with high calorific content creates a surge of energy. The entry of sugar into our minds and bodies begins the upswing of a mood.

In short: The sugar high is not a myth.

This feeling—the sugar high—could feel like the rush of hurtling down a rollercoaster or the mellow feeling of soaking in the sun on a beach. It’s not surprising then that sugar-laden drinks and sweets can give young children a buzz quite similar to what adults experience on caffeine.

But where does this sensation of sweetness come from? When something doesn’t taste the way we remember it is, does it really taste different or is our mind playing tricks on us?

This taste of sweetness we experience—is it all on the tongue? Or is it in the mind?

For centuries, biologists have conducted research to better understand our sensation of taste and its underlying mechanisms. It is natural that we would try to understand why sweetness affects us, it is addictive after all, a feeling that leaves us wanting more.

This sensation of sweetness starts in the mouth, where our tongue has specific receptors that sense the taste of sweet, sour, bitter and umami. However, the entire sensation of flavour is not defined just here. Enter our sense of smell, which plays a vital role in our perception of flavour, and a plate of food.

You know how our taste is affected when we have a cold? On the other hand, a strong aroma of food—often derived from seasonings and spices like red chillies, cinnamon or coriander—builds hunger and anticipation for the dish in concern?

But this isn’t all. The texture of food—be it softness, or crunch—like the crunchy cone of an ice-cream, the melt-in-your-mouth smoothness of a pudding or the chewy sweetness of a rasgulla—also plays a crucial role in the way we perceive something. This is why a soggy piece of cake is disappointing and a perfectly crunchy biscuit induces a feeling akin to satisfaction and joy.

Then there is visual perception, which matters very much as well.

Studies have shown that a round plate can make a dish seem sweeter than when it is served on a square plate. A white plate also increases the sweetness of a dish to its consumer, as compared to a dark plate.

It is not clear exactly why our brain makes these associations. But we can estimate that through our lifetime, we may learn to associate certain visual cues with certain tastes.

Moreover, the part of our brain that processes flavour is also that which is involved in cognition, analysis and the processing of memories. Our perception of flavour is also intimately tied into our previous emotional experiences that we knew as children. Which is why not just any payasam tastes special—it’s the one which your grandmother made every year for your birthday.

What is unique about sweetness as well is that we don’t need to learn to adapt to it. While our preference for other, more complex tastes is something learned through experience, with sweetness it is different. We are hardwired to appreciate something sweet.

But given how pivotal our brain is in creating this multimodal sensation of flavour—it begs the question once again—is the sensation of sweetness all in our mind? Yes, our tongue tastes food first, but can manipulating the mind change the flavour of the dish? 

Researchers have attempted to answer this question through experiments conducted with mice.

After identifying the neuronal circuitry that carries information on sweet tastes, they genetically modified mice to activate these circuits at will.

Researchers found that artificially activating the sweet taste pathway in the brain can make a mouse drink a bitter solution as if it was sugar water…

Keeping this in mind, future deserts might just consist of micromanipulations of your neural pathways, it could become possible to recreate the tastes of your favourite sweets with just the flip of a switch. This could be a game changer for those with diseases who are unable to eat certain food groups or taste certain things. It can also potentially make unappetising food far more palatable.

So, a plate of dessert, a barfi, a piece of chocolate isn’t just about sugar, but it is a multi-sensory, social experience. When we have a plate of caramel custard  placed in front of us, our mind undergoes a complex process of thinking and feeling that allows us to experience its flavour.

Whether it is the feel of the spoon sliding through it as you scoop it up, the scent of vanilla, the mildly bitter burn of the caramel, the silken texture of the pudding—they together create the delicious experience of “tasting caramel custard”.

From the visual appeal and presentation, to the taste, texture and smell, and our previous memories of that dish—everything matters in this sensation we call sweetness.

Nowadays, sweetness is also associated with guilt and unhealthiness, as it is a prominent flavour in many processed foods. Nevertheless it is far more than that. It is a complex sensation—one we will continue to search for, both in the sad and joyful moments of our lives.

Of all the tastes and sensations, sweetness in particular is special because many communities across the world have strong cultural ties to it. The complexity of this relationship is best pondered in the kitchen late at night, your favourite dessert in hand.

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