Term of Japanese origin for the now scientifically recognized fifth taste sensation, which is perceived through the presence of glutamate in food or drink. Chemically speaking, glutamate is the sodium salt of the amino acid glutamine. Amino acids are the basic building blocks for proteins. This substance develops taste-enhancing properties in food and plays a special role in the palatability and acceptance of many foods. Glutamate (or glutamic acid) is found as a building block in almost all proteins, which means that it is consumed with almost every meal. Vegetable proteins can even contain up to 40% glutamic acid. However, glutamate should never be confused with gluten (glue protein), to which some people are allergic.
In living cells, glutamic acid is necessary for detoxification processes and as an energy supplier. It is also the most important neurotransmitter for the transmission of stimuli between nerve cells. Only free glutamic acid or its salt functions as a flavour enhancer. In food spices such as Maggi or Knorr, the relevant proportion is glutamate. Particularly high glutamate concentrations are found in meat (especially in raw state like beef tartar), in human breast milk (22 mg/l), in ripe tomatoes (140 mg/l, four times as much in tomato paste), in fish, in yeasts, in soy and in cheese (in ripened Parmesan cheese even up to 1,200 mg/l). Pure glutamic acid tastes even sweet and sour and intensifies the taste of salty foods. The use of these properties has a long tradition in Far Eastern cuisine.
Asian cooks used extracts from large algae (species Laminaria japonica) for food preparation more than 1,500 years ago. As early as 1908, the Japanese scientist Kikunae Ikeda (1864-1936) discovered that glutamate gives a full-bodied taste in protein-rich dishes. He called the taste direction "umami". This means "meaty, hearty and tasty" or is also a synonym for "greatest delicacy" or "pleasant taste" and is also understood in Japanese as an intensively experienced pleasure. Today glutamate is used in many foods worldwide and has the ADI limit "not specified" according to the WHO. This means that it can be ingested by humans without restriction. For a long time, glutamate was mentioned as the cause of the "China restaurant syndrome" with symptoms such as headaches and nausea. However, this has not been confirmed in any way in double-blind experiments.
In addition to the four traditional taste sensations of bitter, salty, sour and sweet, umami was proven to have a fifth taste almost 100 years after the discovery of Ikeda in 2002 by the American scientists Charles Zucker and Nick Ryber at MIT (Massachusetts Institute of Technology) (in 2006, the sixth taste was also added as fat). Until then, it had been assumed that the sensation was merely a mixture of the other four tastes. The receptors (nerve cells) responsible for the perception of glutamate were found in the taste buds of the tongue. And just as with the other four, there are cells in the brain that explicitly receive and reproduce umami.
Since wine contains amino acids, umami could also be objectively identified if it is present. The only problem is that according to the above-mentioned studies the receptors on the tongue are only weakly developed (1 in 100) compared to the receptor sites in the brain. One phenomenon is that glutamate in combination with a wine containing bitter substances, as is the case with wine aged in barriques, increases the bitter effect. This may be the case, for example, when enjoying Parmesan cheese or smoked salmon accompanied by a wine aged in oak barrels
Picture left (edited): Copyright: Peter Hermes Furian
Right image (edited): From NEUROtiker - Own work, CC BY-SA 3.0, Link