The Sweet Taste

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Complete abstinence is not necessary

»The fact that we react to sweet things with preference and to bitter things with rejection is innate«, says Dr Maik Behrens from the Leibniz Institute for Food Systems Biology at the Technical University of Munich in an interview with PTA Forum. The biologist knows that this is not only the case in humans, but also in many other vertebrates. Sweet is one of the five basic flavours that are conveyed via the taste cells on the tongue. Bitter, sour, salty and umami – often referred to as meaty – are also among them. Whether other flavour qualities such as fatty or salmiak-like also belong in this category is always under discussion, but has not yet been proven.

There is a good reason why our brain can differentiate between these five special flavours: »Each taste quality has its own physiological meaning«, explains Behrens. For example, salty is important for our electrolyte balance. »We like a certain saltiness in food because we lose salts every day and it is important to regularly supply the body with these electrolytes.« High salt concentrations, on the other hand, would not taste good, as they tend to be harmful. Sour, on the other hand, is an indicator of unripe fruit, which is intolerable and should therefore be avoided. Bacterially spoiled food also often tastes sour, so this flavour quality is more of a warning. The same applies to the bitter flavour, which prevents us from eating poisonous food. Sweet and umami, on the other hand, are designed to recognise the vital energy in food. In the case of sweet, it is carbohydrates; umami indicates proteins and their building blocks, the amino acids.

Incidentally, there is only one type of receptor for the basic sweet flavour, to which sugar molecules dock. In contrast, the tongue is equipped with around 25 such receptors for tasting bitter flavours. There are genetic differences in these receptors, meaning that some people are unable to perceive the bitter-tasting substance PROP (6-n-propyl-2-thioruacil). This could also explain why some things taste completely different to different people. Behrens knows that there are only subtle differences from person to person when it comes to the perception of sweet flavours.

It should also not be forgotten that tasting is much more than the five basic flavours that are conveyed via the tongue. »In common parlance, tasting also includes odour impressions that we perceive retronasally, i.e. via the nasopharynx, when we chew«, says the expert. Ultimately, all of our senses play a part in tasting: How does the food feel on the palate? Can you hear a pleasant crunch when something is nice and crispy? Is the food beautifully presented and recognisable as the dish it is? All of this plays a part in whether our mouths water or the majority of the food remains on the plate.

Eating experiences therefore play a major role in our perception of flavour. But can the desire for sweets be trained away? After all, sweet foods in abundance, with their high calorie content, harbour a major health risk today. This is because the body converts sugar that is not directly consumed into fat and stores it for leaner times.

»Tasting sweet things is a strong drive«, says the expert. Those who are very controlled, can safely deny themselves anything sweet. However, the more you have to control yourself, the more likely it is that the opposite will happen at some point and the craving for sweet things will grow stronger.

Nobody has to give up sweets completely. Everyone can do something themselves to limit their sugar consumption. For example, the amount of sugar specified in recipes can usually be easily reduced when cooking or baking without having a significant impact on flavour. Researchers are also looking for substances that are able to enhance the flavour of sugar. If you want to reduce your sugar intake today rather than tomorrow, you should above all avoid ready-made products, which often contain large amounts of sugar. The best way to achieve a healthy sweet intake is to eat a balanced diet with fresh products. It ensures a sufficient intake of fibre, so that blood sugar spikes that fuel the craving for sweets are avoided.

Many consumers are not happy with sweeteners as sugar substitutes. They not only activate the sweet receptors, but also some bitter receptors. This is the reason why they often have a bitter aftertaste. However, some sweeteners even act as bitter blockers, as Behrens’ Taste & Odour Systems Reception working group found out. Researching the effect of individual sweeteners in more detail could help to find the optimal sweetener mix so that sweets give us a sense of well-being even without sugar and calories.