A bitter or sour taste is an indicator of a food that is unripe, rotten or poisonous to the human organism. In general, we tend towards caution and react exceptionally sceptically to new foods; our sense of taste is divided into good and bad from birth.
Our perception of taste, however, is something we need to learn. As well as bad food, certain nutritionally valuable tannins and secondary phytochemicals also taste bitter.
We learn, for example, to value grapefruit and chard, although we would intuitively reject them at the first taste. Secondary phytochemicals – like the monoterpenes found in peppermint or the sulphides that give garlic and onions their typical flavour – are also healthy. They protect us from free radicals, support our immune system in resisting pathogenic germs and can even have an anti-cancer and cholesterol-reducing effect.
- Article "The science of taste"