Editor’s note: This article is based on Chef Koetke’s speech, “Umami: Fact or Fiction, MSG, Cooking and Health,” presented last April at the Michigan Chefs de Cuisine Association conference.
The meaty, savory taste now known as umami finds its best expression through monosodium glutamate. But first, it’s important to understand the wealth of misconceptions surrounding this natural flavor enhancer.
Alittle more than a decade ago, the world of taste was alerted to a monumental discovery. In 2000, a team of scientists at the University of Miami, led by Nirupa Chaudhari, Ph.D., and Stephen Roper, Ph.D., announced definitive evidence of the so-called “fifth taste”—umami. This scientific conclusion hinged on the fact that each taste (previously only sweet, sour, salty and bitter) has its own specific taste receptors in the mouth. Although the idea that an umami receptor existed had been speculated upon for almost a century, identifying the specific taste receptors unique to umami was at the heart of the news. The debate as to whether there really was a fifth taste was effectively ended.
While the scientific confirmation of umami is only 13 years old, it always has been instinctually known, because it is part of basic human biology. The flavor potential umami possesses has long been coveted and recognized as desirous. Indeed, umami is one of the reasons ancient peoples enjoyed cured hams, sausages, cheeses, fermented soy products and fermented fish sauce (garum in ancient Rome).
In his seminal book La Physiologie du Goût, 18th century French politician and consummate gourmand Jean Anthelme Brillat-Savarin tried to describe a flavor he found in older meats and well-made bouillons.  Potentially, what he was sensing was umami. But, without a precise word for it, he used a term invented just 20 years earlier in France: osmazôme. 
The word umami was the invention of Kikunae Ikeda, a chemistry professor at the University of Tokyo. In 1907, Ikeda boiled an infusion of kombu (kelp) to better understand why dashi (a sauce from kombu and dried bonito fish), one of the fundamental cornerstones of Japanese cuisine, tasted so good. He reduced it until only crystals remained. When he tasted them, he found their flavor to be delicious and intensely savory or meaty. Upon analyzing the crystals, he discovered they consisted of a molecule composed of glutamic acid and sodium—monosodium glutamate.
Today, the mention of monosodium glutamate—MSG—conjures up a wide range of reactions from different people. In some parts of the world, it is a common kitchen ingredient, both professionally and in the home. In other circles, it is vilified as a harmful substance that should be avoided. But, the science behind this molecule is key to understanding its taste potential; its role in food preparation; and its safety as a food ingredient. It begins by exploring basic protein science and, specifically, a single amino acid.
That amino acid is glutamic acid, or glutamate, commonly found as part of the amino acid chains that form proteins. Glutamate is the most abundant amino acid in the human body and is essential for proper brain function. Some glutamate is manufactured in the body, while the rest is consumed as part of the proteins in the diet. Each day, the body manufactures about 2.5–5 times the amount of glutamate it gets from foods and beverages.
While people consume glutamate most often as part of other proteins, they do not necessarily taste it as umami. The reason for this is that bodies only perceive glutamate as umami when it is unbound from other amino acids in a protein strand. Only then does umami register with taste receptors in the mouth. 
When glutamate is not bound up in a protein, it is referred to as “free glutamic acid.” Creating free glutamic acid involves breaking the strong peptide bonds that cement amino acids together. This is accomplished through the use of enzymes that cause proteolysis, drying and long cooking. The result is umami-rich foods, including dry-cured hams and sausages, aged cheeses, Worcestershire sauce, miso, soy sauce, fish sauce, tempe, sauerkraut, kimchee, yeast extracts (such as Marmite and Vegemite) and braised meats. Often, the free glutamic acid created then binds naturally with the sodium atoms abundant in many of these foods.
The result is MSG. (Interestingly, ripe tomatoes and older meats also contain larger amounts of free glutamic acid, accounting for their more pronounced umami taste.)
Umami has been described as tasting “savory” or “meaty” and is a taste humans appreciate around the world. It can be incorporated into dishes as part of another ingredient, like those highlighted above, or in its pure form as MSG. Using MSG is similar to how salt is incorporated into a recipe, i.e., by either adding a salty ingredient or by sprinkling in granulated salt. 
Just as the body interprets and processes salt identically, whether in its pure form or as part of another ingredient, it also interprets and digests the free glutamic acid (often bound with the sodium ion) found in some foods the same way as MSG. This is because it is the same molecule.
 At the same time, MSG has been suggested as the culprit behind “Chinese Restaurant Syndrome” (flushing, headache, rapid heart rate, numbness, etc.), various allergic responses and even asthma. While some people continue to believe MSG is inherently unhealthy, the scientific community continues to confirm it as a safe ingredient. The FDA, the Food and Agriculture Organization of the UN, and the European Commission’s Scientific Committee for Food all conclude that MSG is safe. While anecdotal reports of people having negative reactions to MSG continue, no cause and effect has been scientifically shown to exist. Indeed, the FDA has no upper limit on the amount of MSG that can be consumed. Yet, the belief that somehow MSG is unsafe continues to be propagated. 
There is more to the umami story than glutamate. Two additional substances, both classified as ribonucleotides, have been shown to have an important taste relationship with glutamate. The first, discovered in 1913, is 5-inosinate, found in foods such as dried sardines, bonito flakes, mackerel, tuna, pork, beef and shrimp. In 1960, 5-guanylate was identified as one of the important flavor contributors in mushrooms, most prevalently in dried shiitakes.
What makes these compounds so compelling is that they function synergistically with glutamate. Thus, combining 5-inosinate or 5-guanylate with glutamic acid is not a 1+1=2 equation, but rather a 1+1= 4 or even higher. This synergistic relationship is at the core of many common preparations. For instance, dashi is made from kombu (glutamate) and 5-inosinate (dried bonito). It also is behind the popularity of mushroom (5-guanylate) and tomato meat (5-inosinate) sauce topped with Parmesan (glutamic acid).
Understanding where sources of free glutamic acid, 5-inosinate and 5-guanylate reside in various foods is key to maximizing flavor potential. Since time immemorial, food professionals have been harnessing the power of umami-rich foods—and, more recently, of pure umami (MSG)—to create dishes that excite one of the five fundamental tastes and produce deep, rich flavor profiles. The difference today is that people are the beneficiaries of greater scientific understanding about umami and its specific role in flavor development.