What are the basic tastes?
Based on the information that is transported from the tongue to the brain, there are thought to be at least five basic qualities of taste. Most dishes are made up of a combination of different tastes. Some dishes taste sweet and sour, for example, while others are salty and savory. The basic tastes are:
Sweet
When something tastes sweet, it’s usually because of sugar and or derivatives such as fructose or lactose. But other types of substances can also activate the “sweet” sensory cells. These include, for example, some protein building blocks like amino acids, and also alcohols in fruit juices or alcoholic drinks.
Sour
Most things that taste sour are acidic solutions like lemon juice or organic acids. This “sour” sensation is caused by hydrogen ions (chemical symbol: H+). Acidic substances release hydrogen ions when they come into contact with water.
Salty
Most foods that taste salty have table salt in them. The substance responsible for this taste is the salt crystal made of sodium and chloride. Mineral salts such as those containing potassium or magnesium can also cause a salty taste.
Bitter
Bitter tastes are brought about by many very different substances. In total, there are about 35 different proteins in the sensory cells that respond to bitter substances. From an evolutionary standpoint, this can be explained by the many different bitter species of plants, some of which were poisonous. Recognizing which ones were indeed poisonous was a matter of survival.
Savory
The “umami” taste, which can be compared to the taste of a meat broth, is usually caused by glutamic acid or aspartic acid. These two amino acids are part of many different proteins found in foods, and also in some plants. There is a lot of glutamic acid in things like ripe tomatoes, meat and cheese. Aspartic acid is found in asparagus, for example. Sometimes glutamate (the glutamic acid salt) is used as a flavor enhancer. This is done to intensify the savory taste of foods.
Hot or spicy is not a taste
By the way: The sensation “spicy” is very often described as a taste. Strictly speaking, though, it is only a pain signal sent by nerves that pass on information about temperature and touch. Foods that are seasoned with chili powder activate “pain and heat” signals. This is caused by the substance capsaicin in chili peppers.