UMAMI: THE SCIENCE OF THE FIFTH TASTE

Smoked pineapple laksa made with dashi. Photo credit: Eddie Shepherd

Have you ever wondered why a pomodoro sauce sprinkled with tangy Parmesan cheese is so simple yet so delicious? Or maybe it was that uncannily meat-like mushroom dashi that managed to fill your mouth with a certain saliva-inducing savouriness that you cannot compare to anything else? This experience of flavour goes far beyond mere saltiness - this is your mouth encountering something entirely different. But the enigmatic presence of this taste sensation is something which has only recently begun to be fully explored in the West. 

When we were young, we were taught about our sense of taste in terms of four rather arbitrary categories; sweet, sour, salty and bitter. These are known as ‘the four basic tastes’, but in recent years taste research has expanded dramatically as a field of scientific interest in its own right. Some experts claim there are up to fifteen basic tastes (Spence, 2017), while others question if something as complicated and variable as taste can be categorised into such terms at all (Spence, 2017). Yet two things most food scientists, psychologists, and chefs can agree on are the presence of umami and, perhaps as a direct result, the fact that taste is a much more enigmatic and complicated sensory system than we perhaps originally believed.

In more recent years, umami has earned its place at the proverbial table and is commonly referred to as the fifth basic taste. Discovered in 1908 by a researcher called Kikune Ikeda, the word meaning ‘delicious flavour’ in his native Japanese was found in foodstuffs such as meat broth, seaweed and dried fish flakes. Umami is present in a group of glutamates (amino acids) and ribonucleotides (short chain fatty acid receptors) found in protein rich foods such as meat, cheeses, wines, certain fruits. 

It is important to recognize that the taste sensation of umami goes beyond protein and things that hail from the sea. Fermented ingredients and fungi, such as shiitake mushrooms, also have high levels of glutamates & ribonucleotides. Vegetarian chef, Eddie Shepherd, uses umami rich ingredients to add natural all-encompassing savour and “meatiness” to plant-based dishes. He says, ‘I use miso and koji to add flavour and umami in marinades and glazes, adding savouriness and often also caramelised flavours and complex aged notes.’ He continues, ‘I also feature umami rich ingredients like mushrooms across my menu sometimes intensified by concentrating their flavours for a strong savoury hit, maybe matched with smoke flavours to add to the “meatiness” of a dish.’ So we might surmise that the feature in common between the mouthfeel of seaweed based dashi and roasted bone broth is umami - a chemical reaction on the tongue.

Shiitake and Enoki mushrooms Photo credit: Lucas Smith

Adam Reid, Chef de Patron at Fine Dining Restaurant, The French, at The Midland Hotel, Manchester and BBC One’s Great British MenuAlumni, helps us understand the ‘oomph’ of umami. He says that it ‘is like a extra dimension, we have all the normal taste sensations but depth is added with umami rich ingredients and a dish is elevated to the next level.’ In Reid’s opinion, looking to Japan for inspiration in modern cookery has really changed contemporary Western cuisine for the better - and umami is almost single-handedly to thank for this. He goes on, ‘you couldn’t achieve that savoury wow factor without harnessing the powers of umami.’ Perhaps it could be said that umami has taken us out of the dark ages and brought us into a taste and flavour Renaissance. 

In recent years, it has been confirmed that umami has its own taste properties and, indeed, its own receptors which we humans all have the ability to experience. But this begs the question: what is the purpose of us tasting this group of glutamates and ribonucleotides, if there is one at all, other than simple mouth-watering pleasure?

Two types of seaweed (kombu/red wakame) and katsobushi (dried tuna flakes)

Photo credit: Lucas Smith

The first thing we need to understand on this journey is why taste is important in the first place and to do this we will need the help of Professor Paul Breslin - a geneticist and biologist at Monell Chemical Senses Centre and the Department of Nutritional Sciences at Rutgers, the State University of New Jersey. Prof. Breslin researches the genetic basis of human oral perception and its impact on nutrient intake. He is also one of the first scientists to discuss and consider umami as an ‘official’ taste, discovering that its presence is built into our DNA. 

Breslin describes the ‘duality of taste’ and how it has two main functions; firstly as a nutrient detector and, secondly, as a signal to our digestive system of what it is about to encounter. However, to understand this, we must remember that our bodies have not changed for some 200,000 years (Harari 2001), and so our sense of taste is shaped by what Breslin calls the ‘ecological niches’ of our ancestors. He describes it thus; ‘taste we experience now is influenced by how our ancestors hunted and gathered for food. Identifying safe and unsafe foods as well as foods with maximum energy content was paramount for living.’ This applies most importantly to omnivores, Breslin continues, who have a more varied diet and a wider range of foods which means the hazard of accidentally ingesting toxins is greater.  He goes on to describe that what we put in our bodies then was perhaps much more important than it is now. The risks of eating the wrong thing not only increases the likelihood of consuming toxins but it also means wasted valuable energy in a time where survival of the fittest was an ever-wavering balance of life and death. 

Kimchi (Korean spicy fermented cabbage). Photo credit: Lucas Smith

But how does this relate to umami? Well, each of the, what we can refer to as, four ‘classic’ taste receptors, can be linked to a specific nutritional need - to act as a bit of a ‘try before you buy’ feature and to help avoid toxins from things which might look safe on first glance and give you a chance to spit it out. Therefore Breslin tells us that the sweet taste receptor is a marker for carbohydrates or starchy foods, our sour receptor is used to experience sourness in perhaps vitamin C rich fruits (a key vitamin for immunity, growth and general health) and our bitter receptor for the discovery of toxins. But what is the significance of our ability to taste umami?

One idea is that our mothers milk is high in monosodium glutamate (a free glutamate) - but it must go beyond this. Breslin suggests that we do not simply have these complex glutamate and ribonucleotide receptors simply as encouragement to consume our mother’s milk for 2% of our lifetime, the key actually lies in the other half of the science of umami - the ribonucleotides or short chain fatty acids. 

He suggests that we have these receptors in order to develop a predilection for fermented or cooked food combined, which explains why we have a ribonucleotide receptor in the mouth. ‘Ribonucleotides tend only to be present when the food is broken down by fermentation or cooking and short chain fatty acids are predominantly produced by microbes’. And what is the health benefit of fermented foods? The microbes and good bacteria that we need for digestive health and fighting off infections. Professor Breslin summarises this for us nicely; ‘‘it is the fermentation or aging of these foods that releases the glutamate and savoury taste from the protein. Thus, our attraction to amino acids, especially glutamates, and savoury taste may be born from a desire for fermented foods and the advantages of the improved nutrition and probiotic bacteria for our species.’  Looking at foods which we consider to have the most ‘umami’ factor; cheese, wine, miso, soy sauce, cured meats it becomes clear that these are all fermented, cured or aged in some way and therefore brimming with vital probiotics and bacteria vital for nutritional health. 

So, what can learn from this is the impact of taste on human evolution and survival. By and large, although neglected and undiscovered until modern times, umami is perhaps the gateway for us to discover quite how intricate and complex our sense of taste is, and how we might understand it is as, arguably, the most durable, crucial and impregnable of all our sensory systems.