the science behind every bite – Portugal Resident

It guides us in distinguishing safe, nourishing foods from those that might be harmful, while steering us towards energy-rich, nutrient-packed options that our bodies crave.

Like our other senses, taste operates through a remarkably intricate system*. In humans, taste receptors are not limited to the mouth and tongue; they are scattered throughout the throat, epiglottis, oesophagus, and even appear in the gut and lungs, where they play roles in regulating appetite and protecting us from potentially dangerous substances.

The detection process feels almost like a set of Russian dolls. On the tongue, we find tiny bumps known as papillae. There are four types, but only three – fungiform, circumvallate, and foliate – are involved in taste sensation. The fourth type, filiform papillae, focuses on texture and mouthfeel. Within the taste-sensitive papillae sit clusters of taste buds, each with a pore on the surface topped by microvilli – those delicate, hair-like extensions that house the actual taste receptors.

When we chew, food mixes with saliva, breaking down and releasing taste molecules (tastants). These travel through the pores and bind to the receptors on the microvilli, sending signals along neural pathways to the brain to tell it exactly what we’re eating. Yet it would be far too simplistic to credit only the taste buds. Taste receptors are found throughout the digestive and respiratory systems, quietly contributing to our overall experience.

Defining a “basic taste” is not as straightforward as it might seem. Scientists continue to debate the criteria, but generally a basic taste requires its own dedicated detection mechanism and should feel unique, not merely a blend of others. So far, we recognise five: sweet, sour, salty, bitter, and umami. Two more are under discussion – oleogustus (that rich, fatty sensation) and pungency or heat (the fiery kick from chillies or spices).

Sweetness signals sugars and quick energy, which explains our natural craving for it. Beyond the obvious like fruits, sugar, and honey, you will find pleasant sweet notes in fennel, dill, carrots, and avocados.

Sourness (acidity) serves as a warning of possible spoilage, yet it also brightens dishes and stimulates appetite and digestion. Just think how your mouth waters at the thought of sweet-and-sour candies. Common sour delights include citrus fruits, yoghurt, tomatoes, vinegar, and cheeses like goat’s cheese.

Saltiness comes mainly from sodium chloride, essential for fluid balance and nerve function. That’s why we’re drawn to salty treasures such as anchovies, olives, seaweed, soy sauce – and even celery.

Bitterness acts as nature’s alarm against toxins, which is why many of us instinctively shy away from it at first. With experience and time, however, we learn to appreciate it in coffee, unsweetened cocoa, citrus peel, and the quinine in tonic water.

Umami, the Japanese word for “delicious”, was identified by Kikunae Ikeda in 1908 when he isolated glutamate crystals from dried kombu seaweed. This deeply savoury taste enhances everything from aged cheeses like Parmesan to miso, soy sauce, mushrooms, walnuts, and cured meats. It gently encourages us to seek out protein-rich foods.

On average, we have thousands of taste buds – often around 10,000 – which regenerate every couple of weeks or so. As we grow older, this renewal slows, and our sensitivity diminishes. This is why children can find strong flavours overwhelming, while with age we develop “acquired tastes” for things like coffee, olives, blue cheese, and Brussels sprouts.

Genetics also play a significant role. Variations in the TAS2R38 gene, for example, which codes for a bitter taste receptor, can make some people perceive bitterness in cruciferous vegetables much more intensely, leading to stronger aversions.

Finally, taste never works in isolation. It teams up with smell, sight, touch, and even sound to act as a powerful metabolic kickstarter. The mere aroma of apple and cinnamon, or the cheerful sound of whisking, tells our brain and stomach to prepare for something wonderful – say, a delicious apple tart – making digestion smoother and more efficient.

*Sharma, Nik (2020). The Flavour Equation, Chronicle Books, San Francisco.

Read more about food from Beyond taste buds: texture, sound, and the science of mouthfeel