What exactly is taste, and why is it important?
Well into the modern age, taste was regarded as something subjective over which housewives and chefs held sway. It was not until about the 1920s that it became the object of rigorous scientific studies. So it should come as no surprise that it is only within the past few decades that we have started to gain a better understanding of its actual physiological basis. This allows us to explain, in detail, how taste is detected in the mouth by certain receptors and converted into nerve impulses that are then forwarded to specific centers in the brain. The neural cells in these centers carry out the final calculation and convey a message about the food—for example, sweet! or salty!
The first four: Sour, sweet, salty, and bitter
The perception of taste has its physiological origin in the taste receptor cells. These are found in the taste buds, which are embedded in tiny protrusions (papillae) located primarily on the top of the tongue but also distributed over the soft palate, pharynx, epiglottis, and the entrance to the esophagus. There are approximately 9,000 taste buds on the human tongue, clustered together in groups of 50 or so. Each taste bud is made up of 50–150 taste receptor cells. Like other cells, they are encapsulated in a cell membrane, and it is this membrane that holds the secret of taste perception.
The fifth taste: What is umami?
Even though the word umai had been used in Japan for hundreds of years to signify the concept of something delicious, people only became truly conscious of it thanks to the efforts of a single individual—Japanese professor and chemist Kikunae Ikeda (1864–1936), who set himself the challenge of identifying the substance in Japanese soups that was responsible for their fantastically good taste. He found the answer in 1908.
1 + 1 = 8: Gustatory synergy
What is very unusual about umami is that the intensity of the taste it imparts is not solely dependent on how much glutamate is present. To a much greater extent, it is affected by synergistic interactions with other substances that increase its gustatory intensity. Most often this involves a 5’-ribonucleotide, especially inosinate and guanylate. Somewhat imprecisely and proverbially, it has been said that the taste imparted by equal amounts of glutamate and a nucleotide is eight times stronger than that produced by glutamate alone. As we will see, however, the synergistic effect can be much stronger.
Umami from the oceans: Seaweeds,fish, and shellfish
It is likely that many cuisines in all parts of the world originally depended on fermented fish and shellfish, cooked and cured meat, and seaweeds to add umami to a variety of dishes. In both Asia and Europe, preserved fish, together with the condiments made from them, have been used for at least two and a half millennia, and probably since long before then, as a simple, nutritious way to improve the taste of other foods. One might say that the history of using ingredients to prepare food that is rich in umami runs parallel to and reflects the overall evolution of the culinary arts. The heart of the matter is handling the ingredients in such a way that the proteins and nucleic acids are converted to free amino acids and free nucleotides by the skilful use of cooking, brewing, enzymatic fermentation, salting, drying, smoking, and curing, alone or in combination. In the past, these methods were also of great importance to prevent spoilage of the foodstuffs that come from the sea.
Umami from the land: Fungi and plants
As we turn our attention from the sources of umami that are found in the oceans to those that grow on land, we are struck by some important differences. While a great many marine organisms are excellent sources, the number of fungi and plants that would be described as having significant potential to contribute umami is more limited. On the other hand, some are able to supply both basal umami by way of free glutamate and synergistic umami from nucleotides, especially guanylate. And it is among the fungi and plants that we also find a few of the true umami superstars: shiitake mushrooms, fermented soybeans, tomatoes, and green tea.
Umami from land animals: Meat,eggs, and dairy products
In general, there are more free amino acids in the foodstuffs that are made from the organisms that grow in the earth than there are in those derived from the animals that live on it. On the other hand, animal-based foods are good sources of inosinate, which interacts synergistically to signal the presence of proteins. The umami content of meat and dairy products can be strengthened dramatically by preparing them in certain ways or by fermentation and curing. In particular, both simmering meat and bones over long periods of time and fermenting milk result in an abundance of umami.
Umami: The secret behindthe humble soup stock
By far the majority of foodstuffs, when in their raw form, have little umami. Drawing out the fifth taste from them, therefore, becomes a question of breaking down their constituent parts, especially converting proteins into small peptides and free amino acids. Nucleic acids have little direct impact on nutrition, but they unquestionably have influence when it comes to taste and to interacting with glutamate to impart synergistic umami. This is especially true with the humble soup stock, a basic tool in virtually all cuisines. It seems that, since earliest times, cooks in all parts of the world have intuitively found ways to prepare it with ingredients that complement each other, with results that are rich in umami. Here we take a quick look at the chemical underpinnings of their ‘soup science,’ using some well-known stocks as examples.
Making the most of umami
The time has now come to take a little tour of the various ways in which we can tease out umami in our own kitchens. To do so, we have included a number of recipes for both traditional and modern dishes that are made from selected raw ingredients treated in such a way as to take advantage of every last bit of umami in them. First, though, we will make a quick detour to discover some easy tricks for enhancing the taste of foodstuffs that may not be very savory on their own by adding certain readily available products to the dish.
Umami and wellness
Food with umami can often be prepared with significantly less salt, sugar, and fat without sacrificing the delicious taste of the resulting dish. Salt, in particular, is frequently applied too liberally in order to compensate for ingredients that are insipid or unpalatable. In many cases, its use can be reduced by as much as a half by incorporating foodstuffs with umami into the recipe. The fifth taste spurs the appetite, an attribute that can be exploited to advantage in caring for the sick and the elderly, who may have lost interest in eating. At the same time, however, umami promotes satiety, which helps to curb overeating by those who are inclined to overindulge. Either way, adopting a diet that has an abundance of umami may be a way for modern humans to eat in a healthier manner and to adjust their caloric intake to suit the needs of their bodies.
Technical and scientific details
Umami and the first glutamate receptor
Yet another receptor for umami
The taste of amino acids
Taste thresholds for umami
Content of glutamate and 5′-ribonucleotides in different foods
The people behind the book