Tasting bitterness

# Why does bitter taste bitter? Scientifically speaking, the sense of taste is a chemosensor that can perceive the flavors sweet, sour, salty and bitter. It does this by activating the taste buds on the surface of the tongue. The bitter taste is perceived by bitter receptors, which are increasingly found at the base of the tongue (the back of the tongue). There are now 25 different types of bitter receptors identified in the mouth and throat. Five of these react to the bitter-tasting caffeine in coffee, for example. According to evolutionary theory, the bitter taste is associated with toxic substances and the ability to taste bitter seems to be advantageous in this respect. This also explains why the perception of high levels of bitter substances activates stomach acid production in order to counteract possible dangers from bacteria or mold and stimulate digestion. The ability to taste bitter substances varies from person to person and is also based on genetic differences. In fine doses, the bitter taste can give food and drinks a certain something. Well-known examples are: - Citrus fruits (grapefruit, lemon, bitter orange, ...) - Vegetables (spinach, chard, ...) - Herbs (dandelion, nettle, tarragon...) - Salads (chicory, endive, rocket...) - Bitter almonds - liqueurs - Vermouth > ## Bitter is not everyone's cup of tea > > Sour is fun, sweet is tempting - but bitter doesn't suit our taste at all. For good reason: most natural toxins are bitter, especially those in mushrooms and plants. The human sense of taste has adapted to this danger in the course of evolution. This is why the sensory organs of our tongue react particularly sensitively to bitter substances. Children instinctively reject bitterness anyway. It is only during puberty, when the liver matures, that we learn to accept this taste. # What does genetics have to do with it? We are investigating a gene for the perception of bitter taste: The TAS2R38 gene (Taste 2 Receptor Member 38 gene) carries the blueprint in cells for a taste receptor on the tongue that is responsible for the perception of bitter flavors. The gene exists in two variants: AVI and PAV. People who have two AVI copies are hardly sensitive to bitter substances. If two PAV copies are present, certain foods are perceived as extremely bitter. With one AVI and one PAV copy, the sensitivity is in the middle. - Variant rs713598 of the TAS2R38 gene: The G/G and C/G genotypes are able to perceive a wider range of bitter substances via their taste buds. This means that food is sometimes perceived as more bitter. - Variant rs10246939 of the TAS2R38 gene: The C/C and C/T genotypes are able to perceive a wider range of bitter substances via their taste buds. This means that food is sometimes perceived as more bitter. - Variant rs1726866 of the TAS2R38 gene: The G/G and A/G genotypes are able to perceive a wider range of bitter substances via their taste buds. As a result, food is sometimes perceived as more bitter.