What Is Umami? The Fifth Taste Explained

Umami is the savoury, brothy taste you get from stock, aged cheese, ripe tomatoes and soy sauce, and it's recognised as the fifth basic taste alongside sweet, sour, salty and bitter. It's triggered mainly by glutamate, a common amino acid, and boosted by compounds called nucleotides, which your tongue detects with its own dedicated receptor. In the kitchen, umami is what makes food taste deep, meaty and satisfying rather than thin.

Where did the word umami come from?

In 1908 a Japanese chemist named Kikunae Ikeda was eating a bowl of tofu in dashi, the clear broth made from kombu seaweed, and wondered why it tasted so good. It wasn't sweet, sour, salty or bitter, yet it was unmistakably delicious. He went back to his lab at Tokyo Imperial University, boiled down a large batch of kombu, and crystallised the compound responsible: glutamic acid.

Ikeda named the taste umami, from the Japanese word umai, meaning delicious. He also worked out that the sodium salt of glutamic acid was easy to make, stable and pleasant on its own. That became monosodium glutamate, or MSG, sold as a seasoning from 1909.

Two more pieces arrived later. In 1913 one of Ikeda's students, Shintaro Kodama, found a second umami compound, inosinate, in dried bonito flakes. In 1957 another Japanese researcher, Akira Kuninaka, identified guanylate in dried shiitake mushrooms and showed that these compounds dramatically amplify glutamate.

For most of the 20th century, Western science treated umami as a curiosity rather than a true taste. That changed around 2000 to 2002, when researchers identified the receptor on the tongue that responds to it. Once there was a receptor, there was a taste.

How does your tongue detect umami?

The main umami receptor is a pair of proteins called T1R1 and T1R3 that sit together on the surface of taste cells. (T1R3 also partners with T1R2 to make your sweet receptor, which is a neat bit of evolutionary recycling.)

The receptor has a shape a bit like a Venus flytrap. A glutamate molecule settles into the open "jaws", the trap closes, and the taste cell fires a signal that your brain reads as savoury.

There's a catch: only free glutamate counts. Raw meat, fresh milk and young cheese contain plenty of glutamate, but most of it is locked up inside long protein chains, and protein-bound glutamate doesn't fit the receptor. Umami shows up when proteins are broken down into individual amino acids. That's why so many umami-rich foods are aged, fermented, dried, ripened or slow-cooked:

• Ripening raises free glutamate in tomatoes many times over. The jelly around the seeds is the richest part.
• Ageing cheese like parmesan lets enzymes snip proteins apart for months or years.
• Fermenting soybeans into soy sauce and miso, or fish into fish sauce, releases glutamate on a huge scale.
• Drying seaweed and mushrooms concentrates what's already free.
• Long simmering of bones and meat for stock releases amino acids into the liquid.

Why would we have a receptor for this at all? Free glutamate is a reliable signal that a food contains protein. It even shows up in human breast milk at roughly ten times the level found in cow's milk, so most of us meet umami very early.

Which foods are highest in umami?

Amounts vary a lot with variety, age and how the food is made, so treat these as rough guides.

You don't need to memorise numbers. The useful pattern is that glutamate is mostly found in plants, cheese and ferments, while the nucleotides inosinate and guanylate come mostly from meat, fish and dried mushrooms. That split is the secret to the next section.

Why do some umami pairs taste so much stronger?

This is umami's party trick, called synergy. Glutamate on its own is pleasant. Glutamate with a little inosinate or guanylate tastes several times stronger, and in lab taste tests, a roughly equal mix of glutamate and a nucleotide was perceived as up to about eight times as intense as glutamate alone.

The explanation goes back to the flytrap. A nucleotide binds next to glutamate on the receptor and helps hold the trap shut, so each glutamate molecule produces a bigger, longer signal. Two different umami compounds beat a double dose of one.

Once you know this, you see it everywhere in traditional cooking:

• Dashi pairs kombu (glutamate) with bonito flakes (inosinate). It's the original umami synergy, refined long before anyone knew why it worked.
• Ramen broth combines pork or chicken bones (inosinate) with soy sauce, miso or kombu (glutamate).
• A cheeseburger puts beef (inosinate) under cheese, ketchup and pickles (glutamate).
• Caesar dressing brings together anchovies (inosinate) and parmesan (glutamate).
• Mushroom risotto with parmesan pairs guanylate with glutamate.
• Chicken soup with tomato or a splash of fish sauce pairs meat nucleotides with plant or fermented glutamate.

Chef Fizz says: Umami is a team sport. One player is good; the right pair scores big.

Curious how far you can push umami pairs? The Cooking Scientist app has short lessons on umami builders, synergy and fish sauce, with a mini game for matching ingredients to their umami compounds.

Is MSG bad for you?

MSG got a bad reputation from a 1968 letter to a medical journal describing headaches and palpitations after Chinese restaurant meals. The idea of "Chinese restaurant syndrome" spread fast, with more than a little prejudice mixed in.

The research since then is fairly reassuring. In well-designed double-blind studies, where neither the volunteers nor the researchers know who's getting MSG, consistent reactions at normal food levels haven't shown up. The US FDA classes MSG as generally recognised as safe. It notes that some people may report mild, short-lived symptoms such as headache after eating 3 g or more of MSG without food, which is far more than a typical seasoned dish contains.

Chemically, your body doesn't distinguish the glutamate in MSG from the glutamate in a tomato or a wedge of parmesan. MSG also contains about a third as much sodium as table salt by weight (around 12% versus 39%), and because it boosts savouriness, a small amount can let you cut the salt in a dish without it tasting flat.

So the honest summary: MSG is safe for most people in normal amounts. If you personally feel unwell after it, skip it, and you can still get plenty of umami from whole ingredients.

How do you add umami to everyday cooking?

You don't need anything exotic. A few habits make a big difference:

• Brown things. Searing meat, roasting tomatoes or deeply browning mushrooms builds savoury, roasted flavours through the Maillard reaction and concentrates free glutamate as water cooks off.
• Fry your tomato paste. Cook it in oil for a couple of minutes until it darkens from bright red to brick red. Its glutamate concentrates and it gains roasted notes.
• Keep a few fermented boosters handy. Soy sauce, fish sauce, miso and Worcestershire sauce each add umami in a teaspoon. A dash of fish sauce in a beef stew won't taste fishy; it just tastes deeper.
• Save parmesan rinds. Simmer one in soup, beans or tomato sauce for 30 minutes, then fish it out.
• Use the soaking water. Liquid from soaking dried mushrooms is full of savoury compounds. Strain off the grit and add it to gravies, stews and risotto.
• Pair on purpose. If a dish has meat or fish, add a glutamate source. If it's all vegetables, add mushrooms or a little seaweed for nucleotides.

Umami also explains why savoury food can still taste good when your nose is blocked. It's a true taste, detected on the tongue, so it gets through even when aromas can't. More on that in why food tastes bland when you have a cold.

Try it at home

A three-cup dashi test that lets you taste synergy directly. You'll need a 10 cm piece of dried kombu and a small handful of bonito flakes, both sold in Asian grocers.

1. Soak the kombu in 500 ml of cold water for 30 minutes, then warm it gently until small bubbles appear at the edges. Don't boil it, or it can turn slimy. Remove the kombu.
2. Pour a third of this kombu broth into Cup A.
3. Heat 200 ml of plain water to just off the boil, add a small pinch of bonito flakes, steep 2 minutes and strain into Cup B.
4. Bring the remaining kombu broth back to a near-simmer, add a pinch of bonito flakes, steep 2 minutes and strain into Cup C.
5. Add the same tiny pinch of salt to each cup, let them cool slightly, and taste A, then B, then C.

A tastes gently oceanic. B tastes smoky and a little fishy. C tastes dramatically fuller and more savoury than either, far more than you'd expect from just adding them together. That jump is glutamate and inosinate working on the same receptor.

Common mistakes

• Confusing umami with saltiness. They often travel together in soy sauce and cheese, but they're different tastes. If a dish tastes salty but hollow, it may need umami, not more salt.
• Boiling kombu hard. Rolling heat pulls out slimy, bitter compounds along with the glutamate. Keep it at a gentle steam and remove it before the water boils.
• Using only one kind of umami. Three glutamate sources in one pot plateau quickly. Swap one for a nucleotide source like mushrooms, anchovies or meat to get the multiplying effect.
• Adding fish sauce or soy sauce at full strength, then salting as normal. Both are very salty. Add them first, taste, then decide whether you need any extra salt.
• Skipping browning. Pale, steamed meat and mushrooms miss out on concentrated savoury flavour. Give them a hot pan and a little patience.
• Fearing MSG without reason. For most people it's a safe, low-sodium way to add savouriness. Start with a pinch, about 1/4 teaspoon for a pot of soup, and taste.