How Umami Works

People enjoyed umami long before they identified it. Two thousand years ago, for instance, Romans enjoyed garum, a sauce made by fermenting fish until it liquefied [source: Koetke].

The turning point in unmasking umami as a taste came in 1907, when Kikunae Ikeda set out to unlock the secret of dashi [source: Koetke]. Dashi, a staple in Japanese cuisine, is a fish stock made by simmering flakes of dried bonito, a type of tuna, in a broth made from the seaweed kelp, or kombu. It's a main ingredient in numerous traditional dishes, including miso soups (made with fermented soybean paste) and sauces for buckwheat soba noodles and tempura-battered vegetables [source: Wang]. Ikeda noticed dashi imparted the same full-bodied savoriness he'd tasted in tomatoes, asparagus and other foods while studying in Germany [source: Ninomiya]. It was this taste and textural experience that he would later name umami.

Ikeda was no ordinary foodie: By the time he undertook his investigation, he was a chemistry professor at the Imperial University of Tokyo. Accordingly, he began with a chemical analysis of dried kelp. Through water extraction and crystallization, Ikeda flushed out and sorted through its various components. He discovered several salts, including potassium chloride and sodium chloride (table salt) [source: Lindemann]. But as a chemist and dashi aficionado, he knew these were not the source of umami. Finally Ikeda isolated the compound that met both the taste and chemical criteria: monosodium glutamate, or MSG [source: Kenzo]. As the name denotes, MSG is sodium salt formed from glutamic acid. Glutamic acid is an amino acid and amino acids are the building blocks of protein.

A few years later, one of Ikeda's students would identify the main umami component in the dried bonito: inosinate. Inosinate belongs to a class of proteins called nucleotides [source: Kenzo]. Around 1960, scientist Akira Kuninaka identified guanylate, another nucleotide in shiitake mushrooms, as a third contributor to umami. Equally important, Kuninaka found that the relationship among these three ingredients is synergistic: They work together to heighten the umami impact exponentially [source: Ninomiya].

That's the umami backstory. To understand how it works to enhance food flavor, we offer the following short course in taste physiology – a tour of the tongue and beyond.

If it's been a while since you sat in science class, here's a quick refresher: Looking at your tongue, you'll see the surface is covered with several hundred rough-looking bumps, called papillae. Each papilla contains taste buds. Some papillae have a few buds; others have a few hundred. Thus, the buds are scattered unevenly across the tongue. A smaller number lie along the throat and roof of the mouth as well [source: Monell].

Taste buds are the interface between the tongue and the brain. They contain receptor cells, where the chemical chain reaction responsible for taste perception takes place [source: National Library of Medicine]. Just as papillae have varying numbers of taste buds, buds have varying numbers of receptor cells, from one to 700 [source: Monell]. These cells are specialists, genetically coded to provide a pathway to one taste only [source: Roth-Johnson].

The process of taste begins when a food (or any substance, for that matter) enters the mouth. There it's broken down by chewing and dissolved in saliva, bathing the taste buds with its constituent chemicals. Through different means (more on that later), the receptor cell walls translate these chemicals into electric impulses, a process called transduction. Nerves adjacent to the cells relay these impulses to the nucleus of the solitary tract of the brain, or NST. The NST compiles them into a message that identifies the taste.

Taste is the initial factor in determining whether a substance in the mouth is OK to eat. Deciding to eat the food depends on more than taste, however. It involves flavor. Flavor is a multisensory effect. It includes not only a food's taste, but also its aroma, texture, temperature, intensity and even the memories and emotions it evokes. Processing all this information engages several higher-function areas of the brain [source: Monell].

That's the basic route by which food in your mouth becomes taste to your brain. Next, we'll look at umami's particular ways and means.

Umami's food-to-brain protocol varies in certain ways from that of other tastes, starting with the receptor cells. The sensory cells that recognize sweet and bitter tastes and umami are called G protein-coupled receptors, or GPCRs. Sour and salty taste components in contrast, are thought to pass through ion channels, based on positive- and negative-charged molecules [source: Monell].

Three types of receptors cells are known to respond to the combination of inosinate, guanylate and MSG; there are likely more. It's theorized that these receptors not only sense these compounds but also "hold on" to them longer than receptors that target other tastes [source: Marcus]. This would explain umami's ability to reveal nuances of other tastes when experienced together – to make a sweet food not merely sweeter, for instance, but differently sweet. Think of apple pie topped with cheese, prosciutto-wrapped figs or chocolate-coated bacon.

Another remaining question concerns umami's evolutionary role. It's generally accepted that before humans knew anything about health or nutrition, tastes were a guide to which things were good to eat and which ones could kill them. People like sweet tastes because sweet foods, such as fruits and some vegetables, provide carbohydrates and vitamins that can only be obtained by eating them. The umami sensation is provided by proteins, a vital nutrient. But the one amino acid most closely associated with umami, glutamate, is readily made in the human body [source: Geiling].

Other proteins that aren't produced in the body are equally important, however. These are the essential proteins, so named because it's essential that they are included in the diet. Protein itself has no taste. It's the amino acids that, when "freed" from the protein molecule, register on the taste buds. Free amino acids result from processes that break down protein, such as cooking, drying and fermenting [source: Koetke].

Freeing amino acids also starts their digestion and metabolization in the body and some anthropologists suggest this is why humans have advanced beyond other species in brain power (as far as we know). Cooking speeds the breaking down and thus the digestion of amino acids and other nutrients, which enabled human brains to develop more and more quickly [source: Kiger].

The food industry has long known of the profits of using umami. Read on to see how it's popping up everywhere, from fast food to fine dining.

Kikunae Ikeda, the identifier of umami, wasted no time capitalizing on his find. In 1909, one year after identifying monosodium glutamate, he partnered with an iodine processer to patent a commercial MSG-based seasoning, as well as a method of extracting MSG from wheat, a richer source of glutamic acid than seaweed. His hope was to offer an easy way to enhance the taste of nutritious but nondescript homemade meals and thus improve the overall health of the Japanese people [source: Ninomiya]. It's ironic, then, that for many people, MSG as a food ingredient is code for junk food, cheap and unhealthy.

It's true that umami compounds are a favorite additive in the food industry, where their ability to intensify other tastes and add depth and satisfying texture makes them a kind of default "flavor potentiator" [source: Souza]. Besides MSG, you'll see it listed by its industrially prepared sources, including hydrolyzed wheat protein, texturized vegetable protein and autolyzed yeast extract [source: Marcus]. Because these are all natural substances, although they may also be made in laboratories, MSG may be listed simply as "natural flavors" [source: Yacoubou].

Yet, these same qualities could make umami useful in improving the nutritional profiles of commercial formulations. As a flavor enhancer, it can reduce the need for unhealthy ingredients. Also, when made with potassium chloride, rather than sodium chloride, it can replace sodium in some foods. Its meatiness, which creates a fuller mouthfeel, could make low-fat foods more filling and satisfying to eat [source: Marcus].

The applications can be especially beneficial to older adults, who often experience weakened senses of taste and smell and people who take medications or treatments that destroy sensory cells [source: Marcus].

Health considerations aside, umami is one of the hottest trends among cutting-edge chefs and their clientele. The gourmet hamburger chain Umami Burger is named for it and exploits the taste by adding powdered mushroom and seaweed to its ground beef and topping the burgers with soy sauce [source: Geiling].

The home kitchen also provides opportunities for umami utilization. We'll wrap up this investigation with some ideas to spark your culinary creativity.

Given its universality, it's no surprise that umami shows up in a world of cuisines, from the Danish smorrebrod (open-faced sandwich) of roast beef and pickles on sourdough rye bread, to the American BLT. Just the same, here are a few culinary tricks to maximize umami:

In cultivating the umami in foods, you may also expand your repertoire of culinary skills. In a sense, you are developing your own personal umami: your ability to coax out and magnify food's natural flavors.