The main reason we enjoy mushrooms is because of they have a rich, savoury flavour, much loved by consumers, chefs and cooks the world over. The unique taste and texture of the mushroom makes it a favourite with meat eaters and vegetarians alike. What is it that makes mushrooms so tasty? It is the natural glutamates in mushrooms that give them their deep flavour.
Glutamate is an amino acid that is found in all foods with protein. Glutamate is also produced by the body, with high levels in the muscles and the brain. Glutamate is used as a neurotransmitter in the brain by half of all nerve cells.
The glutamate level in the mushroom increases as the mushroom matures from a button to a flat mushroom. Natural glutamate is also responsible for much of the flavour in Parmesan cheese, soy sauce, anchovies, tomato juice, Vegemite and Marmite.
Umami is a Japanese term first coined by Kikunae Ikeda, professor of physical chemistry at the University of Tokyo, in 1908 for the taste of a broth made from seaweed, dried fish and shiitake mushrooms (Chen 2009, Kurihara 2009). Umami is the colloquial Japanese term for “tasty”.
We often hear that the range of tastes in food include salty, bitter, sweet and sour. Foods with natural glutamates provide a fifth taste, now called umami, describing a food that has a savoury or meaty taste. It appears that the combination of glutamate and a savoury aroma links both the taste and smell neural pathways in the brain, resulting in a very pleasant flavour. (Rolls 2009)
Potential role of glutamate
Glutamate is a major fuel for the gut. Glutamate is extensively metabolised by the intestines and therefore, not all of it is absorbed by the gut (Burrin 2009). Glutamate is a signalling molecule in the nervous system of the intestines. The intestinal metabolism of glutamate probably occurs mainly in the enterocytes in the epithelial cells of the intestinal lining (Burrin 2009). Free glutamate may also be absorbed via the stomach and be involved in the digestive function, such as contractile actions of the intestines, gastric acid secretion and blood flow.
Certain proteins, called hydrophobins, are found only in mushrooms and these proteins contribute to the texture of the mushroom, making eating them so enjoyable. It is the combination of natural glutamates, protein and other natural flavour compounds that makes the mushroom texture and flavour so pleasurable.
You can now see why mushrooms are the flavour that everyone enjoys and why they are a very successful substitute for meat. We sometimes consider mushrooms as the meat-eaters vegetarian choice. It also helps to explain why mushrooms complement so many meat dishes.
The natural free glutamates in mushrooms are not to be confused with artificial flavour enhancers. In fact, with mushrooms in the meal you probably don’t need to use salt or flavour enhancers.