Flavor Notes

Maximum Umami?

by Dr. Arielle Johnson

Dr. Arielle Johnson is the Science Director at Noma Projects. With a PhD in Flavor Chemistry, Arielle was a key member of the research and development team at noma and a part of establishing its original fermentation lab. Before rejoining the team at Noma Projects earlier this year, she has been across many exciting projects including her work at the MIT Media Lab.

The other day we got talking about “what is the most umami you could put into something?”  

The dumbest, most brute-force answer to that question is to think like a chemist: umami is the taste of the molecule glutamate, so, what’s the most glutamate you could cram into something? If that “something” is water, the answer is about 650 grams per liter or 65% by volume. If you were stupid enough to do that, you could probably consume enough of it to get close to the lethal dose of glutamate (as measured in rats, about 16 grams per kilograms of bodyweight—as a benchmark, the lethal dose of salt is about 3 grams per kilogram). So, while it’s nice to know a theoretical upper limit to the concept of Maximum Umami, the practical answer is going to be significantly lower.  

As a taste, umami is part chemistry and part sensation. Part of it is material you can measure, and part of it happens inside your brain. The link between the two is the umami taste receptor, which grabs glutamate molecules and trips the signal to the brain that it is experiencing the corresponding amount of the feeling of umami. Taste and smell receptors usually have a saturation point: they’re like a bunch of catcher’s mitts sticking out of the surface of your tongue and nose, waiting to catch the correctly-shaped “balls”. If you start throwing more than they can catch at them, they’re going to send the same “high” signal regardless of how much more than maximum capacity they’re at.  

So you could reasonably approach this question like a neurobiologist, and ask what the maximum amount of glutamate the umami receptor can handle is. Scientists have done some good research on the dose-response curve of the umami receptor, but since we’ve only known about it for around 25 years, they’ve been mostly spending their time on more useful versions of this question, and not the “poke-it-with-a-stick” approach of trying to deliberately overwhelm the receptor. For isolated cells growing in a petri dish, the number looks to be around 160 mg per 100g, but since we have them over our whole tongue, the answer for most people is almost certainly quite a few times higher than that.  

We (and I presume, you also) care about umami not because we’re particularly excited about the glutamate molecule or the umami receptor as isolated phenomena—we want to know because we like delicious food, and want to understand how it works. In that context, useful questions look less like “what’s the highest limit of solubility for glutamate?” or “How much can the receptor take?” and more like “What kind of foods have a lot of umami from glutamate?” and “where does that glutamate come from?” and “can we make more of it” and “what molecules or flavors can enhance umami indirectly?”

Approaching the question like a flavor chemist, I’d want to know how much glutamate tends to be present in food, and what foods or ingredients have the most. This is a question that there is a lot of data to answer, if you know where to look. (two good places that have pulled lots of literature together into single sources: The Umami Information Center website, or Ole Mouritsen’s book Umami). The short answer is: kelp (konbu, specifically), nori, aged cheeses, fermented fish, fermented soy, and dried mushrooms tend to have the highest levels of glutamate, potentially above 1000 mg/100g and up to 3000+ for the most umami-rich kombu. 

Since cooking doesn’t just mean assembling ingredients, the biochemist in me wants to know if there’s anything we can do to increase the amount of free glutamate in an ingredient that feels lacking in umami. Looking at the list we just saw, there’s a lot of protein-rich ingredients (milk, fish, soy) that have been fermented or aged. The process in common? Breaking down those proteins over time, enzymatically. Proteins are made from a grab bag of 20 amino acids, including glutamate, but many proteins have a disproportionately high amount of glutamate woven in, about 20% of their weight. If you unleash protease enzymes—one of the best sources of which is the mold Aspergillus oryzae and the koji you can make from it—onto these proteins, they’ll eventually chew them up entirely and free all that glutamate to be tasted as umami. The theoretical upper limit for typical protein-rich ingredients is about 2600-3300 mg free glutamate per 100 grams (which, if you’ve been paying attention, is pretty close to those upper-level umami ingredients—meaning fermentation, given enough time, is one of the most effective ways to umamify protein ingredients. 

Thinking about maximum umami like a sensory scientist, I might take it as a given that the ingredients I’m using have a certain amount of glutamate in them. And maybe even that I’d freed as much glutamate as possible from as many proteins as possible. Is that the end of the story? 

Certainly not! Not least because glutamate isn’t the only factor in umami. Our sense of flavor is full of amplifications, enhancements, and synergy through suggestion, that makes eating as interesting an experience as it is. 

Some things can augment umami directly. Food molecules called ribonucleotides enhance the umami intensity of glutamate by interfering with the umami taste receptor. They can’t activate it on their own (so they don’t taste particularly umami) but, they keep any molecule of glutamate clamped into the receptor for way longer than normal, which is like keeping your finger on someone’s doorbell. One press, but it keeps ringing and ringing. Same thing with the umami receptor and ribonucleotides—they can make an umami taste signal up to eight times more intense.

The supreme queen of secret umami enhancement is the absolutely ribonucleotide-packed ingredient Katsuobushi, the cooked, smoked, dried, and fungally-fermented loins of bonito that are an essential ingredient in many types of dashi, and hold a second title as the hardest food ingredient in the world. Other strong sources are fresh fish and meat, dried mushrooms (or fresh shiitake or matsutake), asparagus, nori, and tomatoes.

Since our sense of flavor is basically about figuring out how to feed ourselves, get the most out of that food, and avoid poisoning ourselves, there’s a lot of mutual signal enhancement going on behind the scenes. With flavor, never underestimate the power of suggestion. Sweet things will literally taste sweeter if they have aromas we associate with sweetness, like fruity or caramel-y ones. Same thing with umami: we associate funky, aged, cheesy, fermented, seaweedy aromas so much with umami, they amp up whatever umami is there in a big way. Unlike ribonucleotides, not so much of this happens at the umami receptor, and more of it in the places in the brain that package all of the separate flavor signals together into one. 

Kokumi, a sensation of thick and rich mouthfeel and lingering richness, is neither a taste nor an aroma—we sense it with CaSR receptors, which are usually used for sensing calcium ions. This weird not-a-taste can make glutamate-water solutions taste around 50% more umami-intense in lab settings. Kokumi comes from small molecules called peptides, especially Glutathione, a 3-amino-acid long chain of glutamate, cysteine, and glycine.  

Some good places to find kokumi peptides include beef, chicken, foie gras, scallops, tomato juice, brewed alcohol, soy sauce, garlic, onions, and long-aged cheeses like Gouda. Like free glutamate, it’s often, but not exclusively, associated with protein-rich aged and fermented ingredients—places where proteins have had time to break down into smaller pieces. 

Just throwing together the most umami-rich or umami-enhacing ingredients and calling it a day may guarantee you’ve made an umami bomb, but it doesn’t guarantee that what you’ve made is as delicious as possible. Finding the umami sweet spot is less like layering every strategy on top of each other, and more like my grandmother’s rule (lifted from Coco Chanel) for dressing with good taste: when you leave the house, look in the mirror—then remove one accessory. 

Cooking is a craft and an art because it requires you to pay attention, work with what you taste rather than how something is “supposed” to taste, and adapt to your ingredients using your judgement and intuition. On the other hand, thinking about umami like a chef doesn’t have to mean rejecting data and going with vibes only. It means using numbers and/or science for as long as they’re helpful—but trusting your palate as the final judge. Practically, it’s having that knowledge in your back pocket—as numbers, or even just as general trends—and using it to make decisions as you go. 

Ways to get more umami, maximum or otherwise (to use as your palate and judement see fit).

  • Use glutamate-rich ingredients like kombu, fish sauce, fermented soy, cheeses, dried mushrooms, dried tomatoes, or autolysed yeast. 
  • Rule of thumb: aged proteins, seaweeds, plants 
  • some mid-range (but still pretty glutamate-heavy) ingredients: walnuts, green tea, dry-cured ham, sake, fresh tomatoes, fresh molluscs like squid or scallop, corn, peas, potato, garlic, cabbage. 
  • Ferment protein-rich ingredients with protease-rich microbes like Aspergillus oryzae (in koji) and some lactic acid bacteria or blue cheese molds. 
  • Turn up the signal from naturally-occurring glutamate with ribonucleotide-rich ingredients like katsuobushi, fresh fish or meats, and for the non-meat eaters, mushrooms (especially dried), tomatoes, asparagus, or nori. 
  • Use kokumi-rich ingredients to create a sensation of richness that amplifies umami: garlic, onions, tomato, soy sauce, brewed alcohol (like beer or wine), foie gras, chicken, or beef. 
  • Enhance umami with other flavors: saltiness, sweetness, funky/fermented, cheesy, seaweed-y, meaty. 
  • Glutamate is really soluble in water and pretty poorly soluble in fat: infuse glutamate-rich ingredients in water (or wine, sake, juice, something water-based) for maximum umami transfer 
  • Glutamate is non-volatile: you can boil down or reduce a glutamate-rich liquid to remove water and concentrate the umami, if you don’t mind that it changes the aroma (that change might be delicious)

Flavor Notes

Travel Letter from Kyoto

by Kevin Jeung. 

Jeung is Chef of Research and Production for both noma and Noma Projects, spending most of his time in the Fermentation Lab. Jeung spent three months in and around Kyoto as part of the noma Kyoto pop-up where the team researched new and exciting ingredients and production methods.

What an exciting time to be a Noma team member! Here's a peek into what it was like during our travels and experiences in Japan for our pop-up in Kyoto.   

 As the weather warms up, new life has begun to spring forth from the ground in anticipation of summer. In a way, the arrival of spring is the perfect metaphor for our pop-up in Kyoto; a finite moment in time and place to showcase an array of techniques, ingredients, and concepts that we've developed for years in preparation.  

A natural starting point in delving into Japan's food traditions was to explore katsuobushi and kombu, the main components of dashi, which is the backbone of Japanese cuisine, and a broth of vigor and rich with umami.

Starting with the craft of katsuobushi making, together with a fourth-generation craftsman, we explored the possibilities of the process beyond bonito. In collaboration, we experimented with using pumpkin, corn and other vegetables in place of the traditional fish. The results were delicious, and not only did we use them in our menu in Kyoto, but we will definitely take them with us in our future menu development at noma and in our product development at Noma Projects.

Hand in hand with katsuobushi, kombu completes the dashi base. So, we went to Hokkaido, where most of Japan's kombu is harvested to examine its history and role in the development of MSG. We also tasted several other varieties of seaweed that were new to us. On our menu, we featured a selection of these seaweeds in a hotpot course, where diners were encouraged to dip different fresh seaweeds into a pot of roiling broth. In a moment of surprise and delight, some of the seaweed flourished from deep forest green to bright green when swirled through the hot liquid. You can read more about the science behind that color change and why certain seaweeds bloom different colors when heated.

Beyond exploring those two pillars of Japanese cuisine and culture, a highlight of our research for Kyoto was in discovery of ingredients that were totally new to us. Occupying several spotlights on the menu were products never-before-used by the noma kitchen. The euphoria of tasting something completely new was shared many times in the kitchen during the development of our menu.  

  • We tasted green rice for the first time that was grown and harvested by a single farmer.  
  • We returned from Okinawa with crates of sunshine-yellow egg fruits, cradling the fragile treats and ripening them with intention and attention.  
  • We tasted misozuke tofu from Fukuoka, a very traditional preparation that, while known to some for generations, was completely original in our eyes. This vegan foie gras-like product lends richness to a confit of fragrant and striking red ginger. 

Opening during bamboo season allowed us to feature the meaty, fast-growing shoots for the first time. Of course, celebrating seasonality also means missing out on ingredients whose time has passed. Though we weren't able to feature whole Sawagani, or freshwater crabs, on our menu, we harvested them during their season ahead of the pop-up and fermented them into a garum, allowing us to draw the essence of the crabs into our dishes despite the fresh product being out of season.  

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Then there are ingredients that we already use at Noma, like roses and black garlic, which have roots in Japan. It was a supreme thrill to use these native ingredients in situ, simultaneously honoring their origins while celebrating new ways of using them. 

It's impossible to mention roses in Japan without mentioning another flower that holds such esteem in this country; the cherry blossom. Sakura season came and went during our time in Kyoto. Our staff were treated to a once-a-year, only-in-Kyoto spectacle of color and beauty for the brief flash of pink and white flowers all throughout the city. We were able to capture the flavor of this special moment in our menu both by serving preserved cherry leaves and by creating a rich, marzipan-like oil from the cherry wood—using a process we apply to black currant wood back home—the flavor of which completely blew our minds.  

The passing of flowers, typically means the advent of fruit. With no shortage of amazing fruit in Japan (read our post about how the Japanese utilize selective pruning to yield small crops of magically delicious fruit), we applied our usual process of slowly drying in fresh fruit to the best of what was in season. Slow-drying the incredible produce here armed us with concentrated fruit flavors and a less-conventional sweetening option for our menu. 

When the dehydrators weren’t drying in strawberries, kiwis, and huscup berries, they were slowly reducing and concentrating the umami in our tamari-like reductions. A low and slow mentality applied to flavorful liquids derived from our ferments opens the floodgates on flavor, with rich, thick, sticky drops of umami playing secret MVP all over our menu.

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These flavors and ideas took time to come to fruition, and the test kitchen has since begun to move on to preparing for our homecoming this summer in the middle of the bountiful Scandinavian summertime. The Shinkansen may have an end to its line, but the noma train rolls on—our test kitchen is already hard at work in Copenhagen laying the track for our next voyage. That's the magic of Time and Place; time goes on and places can change. We will of course miss Japan and all its wonderful, delicious, and beautiful ways of life, but we cannot wait to unleash the supernova of creativity that comes with experiencing other cultures and immersing ourselves in another world. Tokyo 2015 changed the game for us, not to mention Australia and Mexico, and Kyoto 2023 is sure to continue that trend. Stay tuned. Stay curious. 

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