Umami from the land
Umami from the land
Fungi and plants
Abstract and Keywords
This chapter focuses on two sources of umami that grow on land: fungi and plants. While a great many marine organisms are excellent sources of umami, 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. This chapter first looks at umami sources that belong to the plant kingdom and goes on to discuss dried fungi, fermented soybeans, soy sauce, the production of shōyu and miso, and fermented soybean cakes. It also considers black garlic, shōjin ryōri, tomatoes, and green tea.
I often think of my Alsatian grandmother. … When I was little I used to love spending time in the kitchen with her and watching her work. She would talk to me about what she was doing. She was forever trying to improve her recipes, to add a little more of this, a little less of that, so that everyone would he happy.
J’ai souvent pensé à ma grand-mère alsacienne. … Ce qu’elle me donnait, c’est surtout d’y avoir passé pour moi du temps en cuisine. Je la voyais faire; elle ne cessait de perfectionner les préparations, d’y ajouter ceci, d’éviter d’y mettre cela, de me dire ses idées, de tenir compte des goûts de tous.
Hervé This (1955-)
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 the plant kingdom
As fruits and vegetables mature, they develop a more intense taste. Ripe tomatoes and ripe green peas are especially good sources of glutamate, as are cabbage and mature potatoes that have been cooked. Of the plants that contain nucleotides, tomatoes and potatoes are again prominent and are joined on the list by green asparagus, lentils, and spinach. A particular plant extract, green tea, is also able to impart a strong umami taste.
Generally speaking, fruits have very little glutamate and are not able to contribute to umami in any significant way. Tomatoes are a spectacular exception to this statement, as their free glutamate content increases dramatically over time. When ripe, they have ten times more glutamate than when green. Without it, they taste tart, much like a tomatillo or a citrus fruit. As they ripen, their sugar substances and organic acids are also developing.
Some nuts and seeds, such as almonds, sunflower seeds, and especially walnuts, are also good sources of umami. Soybeans, which are oilseeds, have a special relationship to umami. They are among our most protein-rich foodstuffs. They contain all the essential amino acids that humans need, but their glutamic acid is bound in the proteins. For this reason, all unfermented soy products, such as tofu and soy milk, have only a little umami. The reverse is true once they undergo fermentation. As we will see later, plant products made from fermented soybeans, especially in the form of soy sauce and hydrolyzed vegetable protein, are, from a global perspective, among the processed foods that are most widely used to impart umami.
Of the cereal grains, only maize (corn) can contribute free glutamate when it is in the unprocessed state. Rice, despite its large content of proteins with glutamic acid, has only insignificant quantities of free glutamate. The picture changes completely when it is brewed or fermented for purposes such as making sake or rice vinegar. The same is true for other grains, such as barley and wheat, which are used to make beer. Bread baked with cereal and flour products can also yield umami, particularly if the dough is allowed to rise slowly with the help of either yeast or sourdough. Yeast and lactic acid bacteria release the glutamate in the proteins of the cereals. ···> Seriously old-fashioned sourdough rye bread (p.107) (p.108) Sourdough bread made with white flour is wonderful when it is freshly baked and the crust is crisp. Day-old bread can still be used and find a key place in a real umami celebration. ···> Anchovies, grilled onions, sourdough bread, pata negra ham, and mushrooms
When rehydrated, fungi are the raw ingredients that contain by far the most guanylate. (See the tables at the back of the book.) Shiitake and matsutake mushrooms, along with morels, top the list. Dried shiitake mushrooms also contain large amounts of free glutamate and hence can contribute both basal and synergistic umami. Yeast, which is also a fungus, plays a very special role, as the yeast cells contain a great deal of glutamic acid. If the individual yeast cells are split open, the cells’ own enzymes can break down their proteins by hydrolysis, thereby releasing large quantities of free glutamate. This process is exploited in the industrial production of yeast extract, as we will see later. Yeast extracts are widely used in commercially processed foods to add umami.
Dried fungi are one of the most important non-animal sources of 5’-ribonucleotides, especially of guanylate, which synergizes with glutamate to produce a stronger umami taste. Generally, fresh fungi contain only a little guanylate, but in the course of the drying process free nucleotides develop, up to a level of 150 mg per 100 g. Also, the fungi that are darkest in color are normally able to impart more umami. Truffles are an exception to this pattern, as the white ones are richer sources than the black ones.
The shiitake mushroom is the classic example of a fungus in which guanylate is formed as it dries out. As mentioned earlier, they have a historical association with umami, in that the Buddhist monks in Japanese temples found out centuries ago that dried shiitake mushrooms could be substituted for katsuobushi to make a pure dashi without any animal products.
Shiitake mushrooms are a very popular and highly prized ingredient, second only to button mushrooms as the most cultivated mushroom in the world. When fresh, they have a woody and slightly acidic taste, but (p.111) as they dry they develop a wide range of taste and aroma substances, especially lenthionine, which is formed in the lamellae (gills) by the action of the mushrooms’ own enzymes. This same process is repeated when the dried fungi are rehydrated in tepid water (30–40ºC). In order not to weaken this enzymatic activity, it is important not to soak the mushrooms in water that is too warm or to cook or toast them.
There is a particular variety of highly prized shiitake mushrooms with small, dark caps called donko. These ripen over a long period of time and consequently develop more guanylate and are able to contribute more umami.
Other dried fungi that have a large guanylate content are morels, with 40 mg per 100 g, as well as porcini and oyster mushrooms, both with about 10 mg per 100 g. The Japanese mushrooms matsutake and enokitake are also good sources of umami.
Products made from fermented soybeans, in the form of liquids and pastes, are among the most widely used and oldest taste enhancers in the world and, in the form of protein-rich solids, they are ingredients in their own right in many prepared dishes. In addition to soy sauce, these products include miso, fermented tofu, and nattō, to name just a few.
Soybeans are probably native to Siberia or the northeastern part of China. Very early on in human history, the wild strains were domesticated and cultivation spread throughout East Asia. The oldest preserved samples of cultivars that resemble modern soybeans were found in Korea and date from about 1000 BCE.
There is clear evidence that soybeans were already being fermented in China more than 2,000 years ago. When one of the Han Tombs, sealed in about 165 BCE, was opened by archaeologists in 1972, black soybeans fermented with salt, jiàng (soybean paste), and majiàng, a type of fish paste with soybeans, were among the well-preserved foodstuffs found in pottery jars and identified by name on bamboo slips. Adding soybeans to fish that were being fermented to make fish sauce was a way to make the more costly ingredient stretch further.
Soy sauce is found in the majority of food cultures in Southeast Asia. It is known by a variety of names, including jiàng yóu (China), shōyu (Japan), and ganjang (Korea).
The tradition of fermenting soybeans to make soy sauce probably arose in China, possibly at least 2,500 years ago. The spread of this practice is thought to have been driven by the necessity to limit the use of salt, which was expensive. Soy sauce could easily be used to add both savory and salty tastes to otherwise bland foods, such as cooked rice.
An eighth-century forerunner of Japanese soy sauce, called hishio, was produced from fermented soybeans to which rice, salt, and sake were added. This mass could be separated into a liquid and a more solid paste. The liquid was called tamari, which means ‘accumulated liquid,’ and it gave rise to shōyu, which can be translated along the lines of ‘the oil or thick liquid from hishio.’ The solid paste is equivalent to miso, an important component of vegetarian Japanese temple cuisine, shōjin ryōri. It is thought that the first commercial production of shōyu took place in Japan in 1290.
Modern shōyu is made from soybeans and wheat according to a process that has been in use in Japan since 1643. As wheat helps to impart sweetness to, and increase the alcohol content of, the end product, varying the proportion of these two ingredients results in a variety of taste nuances.
Soy sauce contains a great deal of free glutamate, with the actual amount being to a certain extent dependent on how the fermentation process is fine-tuned. A good Japanese shōyu has about 800 mg free glutamate per 100 g and Korean soy sauce somewhat more, as much as 1,264 mg per 100 g. The salt content is high, ranging from 14–18 percent.
Every country has its own traditional way of brewing soy sauce. In Japan and China, especially, there is a large selection of soy sauces, containing varying quantities of grain and characterized by differences in color, taste, salt content, and consistency. Chinese soy sauce has less wheat than the Japanese types, which are typically made from equal amounts of soybeans and wheat. Some cheaper brands based on hydrolyzed soybean protein are produced using fast industrial methods. This requires a shorter aging period and results in a different taste. A number of these products are actually sold as ‘liquid aminos’ and marketed as an alternative to naturally brewed soy sauce.
(p.113) Brewing Japanese shōyu in the traditional manner takes time. Due to a shortage of soybeans in Japan after World War II, it was necessary to import them from the United States. Furthermore, because of the difficult economic situation at the end of the 1940s, the slow fermentation process, which breaks down the proteins in the beans to free amino acids, was displaced by a faster enzymatically controlled method. Later, there was a return to the classical methods, but in more efficient, modern breweries.
Shōyu was one of the few Japanese food products that the Dutch were allowed to take back to Europe during the 250-year Edo period, when Japan was isolated from the rest of the world by the shogunate. It was exported from their trading station at Dejima, near Nagasaki, and shipped to Europe, where it found favor in the kitchens of the royal French court.
(p.114) Shōyu proved itself to be such an exceptional discovery that it has put its stamp on very many aspects of traditional Japanese cuisine. It is said that one reason why Chinese chefs assimilated globalized aspects of Western cooking so much more rapidly than the Japanese did, to put it simply, is that the latter were so enamored of shōyu that they did not set aside the extra time needed to evolve their cuisine.
The Japanese word for soybean paste is miso. It is thought to have originated at least two and a half thousand years ago in China, where it is called jiàng. Like soy sauce, miso is an offshoot from the practice of adding soybeans to fermenting fish and has evolved over time into a foodstuff in its own right. It is also possible that the forerunner of miso was not connected only with the fermentation of fish but also with that of shellfish and game.
Miso is produced from fermented soybeans together with different types of cereal grains. The process by which it is made is related to that used to brew shōyu. As a broad generalization, one can say that miso is the solid paste that remains after the liquids have been drained away from the fermented soybeans. Here again, the fermentation medium kōji plays a central role.
(p.115) There are many varieties of miso, characterized by differences in color, taste, texture, and how long they have been fermented. Some varieties are shiro miso (white miso), which is very pale, has a mild, slightly sweet taste, and is often used in dressings and confections; aka miso (red miso), which is fermented over a long period of time, taking on a dark reddish color and acquiring a stronger, saltier taste; and genmai miso, made from brown rice. Subtleties of taste and color can also be attributed to the type of cereal grain that goes into the kōji. Although rice and barley are most common, many others, such as wheat, buckwheat, rye, and millet, can also be used either alone or in combination. Some types of miso are made with barley (mugi miso), and a very dark, expensive variety is made with soybeans only (Hatchō miso).
Finally, there are gradations in texture, depending on how finely the soybeans and cereal have been ground. In some cases, the soybeans have been mashed only coarsely, resulting in a consistency that is more like the original miso, which was made from whole beans.
(p.116) On account of its abundance of proteins, minerals, and vitamins, miso has been, and continues to be, an important nutritional resource in Japan. It is most often used to make miso soup. The soybean paste contributes additional umami to the soup, which is already loaded with savory taste substances from the dashi on which it is based. Miso can also be used to season oven-roasted or deep-fried vegetables. ···> Deep-fried eggplants with miso (nasu dengaku) (page 115)
A type of pickle, miso-zuke, can be made by placing vegetables (for example, daikon, marrow, and garlic) in a mixture of miso and sake. As part of the conservation process, some of the characteristic taste of the miso, especially umami, is transferred to the vegetables. The umami in vegetables with moderate amounts of glutamate (for example, white asparagus) can be intensified by combining them with miso and fish. ···> White asparagus in miso with oysters, cucumber oil, and small fish
Soybeans are also fermented to make protein-rich solid foods that are used as main ingredients in a variety of ways. Of the ones discussed here, tempeh and nattō are made from whole beans, while fermented tofu starts out as soy milk.
Tempeh, which comes from the island of Java in Indonesia, is one of the few soybean products that is not originally from China or Japan. It consists of whole soybeans that are soaked, hulled, partly cooked, and then seeded with a mold, Rhizopas oryzae or Rhizopas oligosporus. A little wine vinegar may also be added. The beans, which are still intact, are spread out in a layer and fermented for a couple of days at about 30ºC. As a result, the mycelium from the fungus grows into the beans, so that they are more or less glued together into a cake but maintain the texture of the individual beans.
In the course of three days of fermentation, the free glutamate content in tempeh can skyrocket from about 10 to about 1,000 mg per 100 g, which, of course, dramatically increases its umami. Tempeh also contains a great deal of vitamin B. It has a mild but very complex taste with undertones of nuts and mushrooms and gives off a faint whiff of ammonia. In fact, the aroma is a little reminiscent of that given off by a good Brie at the perfect point of ripeness. Tempeh is often eaten as a replacement for meat, either cooked or fried.
(p.119) A few years ago, a Swedish doctoral student, Charlotte Eklund-Jonsson, succeeded in creating an alternative version of tempeh by fermenting whole-grain barley and oats, plants that grow in colder climates. It is regarded as highly nutritious because, like its soybean counterpart, it has an abundance of folate. In addition, the method she developed was able both to preserve the high fiber content and to enhance the easily accessible iron in the final product, outcomes that are normally mutually exclusive.
Fermented soybean products are also made from tofu, which, like cheese, starts out as a liquid. Cheese is made from different types of milk, which contains lactic acid bacteria, by adding rennet, a complex of enzymes found in mammalian stomachs. The rennet causes the milk proteins to coagulate to form a very soft solid. This fresh cheese can be turned into a range of hard cheeses and soft ripened cheeses with the help of microorganisms and fungi, which break down the proteins to free amino acids. A similar process is used to make tofu from soy milk by adding a coagulant, typically calcium sulfate or magnesium chloride, to it. This causes the proteins to coagulate into a solid mass, which can then be pressed together to make it firmer.
The fresh tofu can be eaten in savory and sweet dishes or fermented to make other products. Just as cheese acquires a more intense taste as it ages, tofu takes on a stronger taste from a longer fermentation period.
Furu, a well-known type of fermented tofu from China, is related to tempeh. It is made from solid cubes of tofu that are air dried, fermented, and then immersed in brine to conserve them. Furu has 381 mg of gluta-mate per 100 g and is often used to add a savory taste to rice or vegetable (p.120) dishes. Its texture can be compared to that of foie gras or a creamy blue cheese, and it has a mild, sweetish taste combined with saltiness from the brine. A special type of furu called ‘stinky’ tofu is fermented for more than half a year in a brine made with fermented milk and some combination of vegetables, herbs, meat, and dried seafood. While it gives off an incredibly strong, offensive odor, its taste is interesting and much milder. ‘Stinky’ tofu is an extremely popular snack food in Taiwan and Hong Kong, where it is usually sold by hawkers in the street and at night markets.
Tempeh and furu can quite correctly be regarded as the Asian answer to cheese. On occasion, furu has actually been called ‘Chinese cheese.’
The Japanese often use nattō as a little test to find out whether foreigners are really seriously interested in their culture. As with ‘stinky’ tofu, it can be a bit difficult to get past the odor and on to the taste. Nattō is made from fermented whole soybeans. It has a truly pungent smell, almost like that of an overripe cheese, and an intense umami taste. In addition, even though the beans are sort of glued together into a stringy, viscous mass, nattō is eaten with chopsticks. In Japan nattō is often eaten for breakfast, together with a raw egg on warm, cooked white rice. It is a very protein-rich food, with an abundance of vitamin K.
Nattō is made from small soybeans that are presoaked and then steamed for several hours before being seeded with Bacillus subtilis nattō, a bacterial culture. The soybeans are placed in a warm, moist environment for a day or so, allowing the bacteria to start a fermentation process. If tradition is being followed strictly, the container used for this is made from woven rice straws. After this short fermentation period, the soybeans are cooled to about 0ºC and left in the cold for a week. During this time, enzymes break down the proteins to free amino acids, mainly glutamate.
The glutamate content of nattō is about 136 mg per 100 g, considerably less than in other fermented soybean products, simply because the fermentation is of such short duration. As no salt is added during fermentation, nattō is only slightly salty in comparison with many of these other products.
Other food cultures prepare a variety of beans in a similar way. Compared to nattō, some of these products have a much greater free glutamate content, for example, 1,700 mg per 100 g in West African soumbala, made from fermented néré (Parkia biglobosa) seeds, and Chinese douchi, made from salted soybeans, which turn black as a result of fermentation. The paste made from them is well known as black bean paste, often used in sauces for Chinese food.
Black garlic is used as a food ingredient in Asia, particularly in Japan and Korea. It has recently put in an appearance at the cutting edge of Western cuisine. The cloves of the fresh garlic turn pitch black after being kept for several weeks at a temperature of 65–80ºC in a closed container with a controlled humidity level (70–80 percent). Although often referred to as fermentation, the process involves enzymes and low-temperature Maillard reactions. During this process, the garlic softens and the rather pungent taste of the fresh garlic turns into a tangy, round, sweetish, and pleasant aromatic flavor with notes of balsamic vinegar and tamarind. In addition, the garlic has a prototypical taste of kokumi that is a delicious complement for dishes with umami.
Shōjin ryōri: An old tradition with a modern presence
The increase over time in the diversity of Japanese dishes made with the concentrated foodstuffs discussed in this and preceding chapters was undoubtedly related to major religious developments. Buddhism became the official state religion of Japan in the sixth century, and this resulted in stringent prohibitions against the consumption of meat and fresh fish, which lasted for hundreds of years. This gave rise to a need to find replacements that could introduce umami to make food more palatable. As a result, dried and fermented fish, seaweeds, vegetables, soybeans, and fungi were placed in the spotlight. Later on, when Zen Buddhism grew influential and the consumption of all fish was banned, it was no longer permitted to make dashi with katsuobushi. This was how the distinctive, strictly vegetarian Japanese version of temple cuisine, shōjin ryōri, began to take shape. In a sense, one can view the core of this cuisine as a search for deliciousness and umami without using any animal products. The only slightly less ascetic branches of modern vegan and vegetarian movements espouse these same goals.
This centuries-old vegetarian temple cuisine, which is still practiced in Japan, has started to put in an appearance in Japanese restaurants in the Western world, where it is being infused with a new life and reintroduced in a modern context. Interest in shōjin ryōri is stimulated by the desire for simple, healthy food that is preeminently based on seasonal ingredients and in which palatability and umami are achieved by special combinations of fresh and prepared foods.
Even though tomatoes are actually fruits, we tend, from a culinary standpoint, to classify them as vegetables. On a global scale, they are the second most important vegetable crop after potatoes. Tomatoes are not just eaten raw, but they are also turned into purées, ketchup, juice, and salsas. Of all the vegetables, they have the greatest content of free glutamate, and it is enhanced when they are prepared in conjunction with other ingredients that contribute synergistic umami, for example, fish and shellfish. This is undoubtedly the reason why tomatoes are so popular and are used in an enormous range of dishes in kitchens all around the world. In fact, tomatoes also have a free nucleotide of their own, adenylate, rendering this popular food ingredient one of the few that can contribute umami synergy on its own.
It can be difficult to distinguish the taste of umami in a ripe tomato, even though free glutamate is one of its most important components. The sweetness of a ripe tomato easily overpowers the more subtle umami. Nevertheless, when it comes to vegetable sources of umami, tomatoes are the champions.
The free glutamate content of tomatoes increases more than tenfold as they ripen. (See the table at the back of the book.) Sun drying them increases the glutamate content even further. In addition, tomatoes also have fair amounts of the nucleotides adenylate and guanylate. This is a good reason to add ripe tomatoes to a green salad, which has little taste on its own.
A scientific article published in 2007 reported on an analysis of the glutamate and 5’-ribonucleotide content in thirteen different varieties of tomatoes. One of the authors is the well-known chef Heston Blumenthal, who has established one of the world’s best restaurants, The Fat Duck, in England. He is a pioneer in the field of molecular gastronomy and also an enthusiastic advocate of umami.
The point of departure for the study was the chef’s empirical knowledge that the umami taste of a tomato seems to depend on whether it is the outer flesh or the inner pulp, including seeds, that is being consumed. Surprisingly, the analysis showed that the glutamate content of the pulp is three to six times as great as that of the outer flesh and that the concentration of adenylate is at least four times as great in the pulp. This means that when preparing a dish with tomatoes, one must be sure to use the pulp and the seeds in order to maximize umami.
As we learned from the experiment with making a Nordic dashi, sunripened tomatoes can be used as a source of glutamate for the stock, for example, in combination with smoked shrimp heads or dried fungi.
The wealth of umami in tomato juice can also be used to advantage in cocktails made with an alcohol that has little taste on its own, such as vodka. A classic example is the Bloody Mary. An even better example is a cocktail inspired by the sauce for a Venetian version of spaghetti alle vongole, made with clams and tomatoes. This is the Bloody Caesar, which combines vodka, tomato juice, clam broth, Worcestershire sauce, and a drop of Tabasco sauce. It is Canada’s most popular mixed drink. But it is, possibly, also its best-kept secret and deserves a much wider following elsewhere.
Mackerel contains large quantities of inosinate, 215 mg per 100 g. When combined with tomato, the synergy between the two ingredients turns the dish into a veritable umami bomb. So it is little wonder that even a simple tin of mackerel in tomato sauce can give so much pleasure. And who has not experienced the fantastically good taste that the traditional Italian Bolognese sauce, combining tomatoes and meat, can add to a simple bowl of pasta?
Because tomato sauce enhances umami, it provides a convenient way to round out the taste impressions in a dish, both by increasing saltiness and sweetness and by masking any bitter nuances. ···> Baked monkfish liver with raspberries and peanuts (page 128). The best way to gain the most concentrated umami taste from tomatoes is to oven-roast cooked whole tomatoes and herbs at low heat. If the tomatoes and herbs are chopped coarsely, the roasted tomato paste will end up with a texture that is similar to that of Bolognese sauce, but without the meat. The (p.128) oven-roasted tomato paste can easily be substituted for a meat sauce in a pasta dish. ···> Slow-roasted sauce with tomatoes, root vegetables, and herbs (page 130)
Baked tomatoes can also enhance the taste of fried fish. When combined with sago pearls, which are basically pure starch but that can be made tasty by marinating them, the result is a dish with substantial umami synergy. ···> Fried mullet with baked grape tomatoes, marinated sago pearls, and black garlic (page 132)
Extracts from green tea leaves have fairly large quantities of free glutamate, for example, about 450 mg per 100 g for those of the highest quality (gyokuro) and about half as much for the more ordinary varieties (sencha). On the other hand, roasted tea (hōjicha) has very little, about 22 mg per 100 g. But there is actually a completely different amino acid that is thought to be responsible for the strong umami taste in green tea.
Green tea leaves have very large quantities of the amino acid theanine, about 2,500 mg per 100 g. It is the most prominent of the taste substances in tea leaves, where it makes up about half of the free amino acids. Theanine is derived from glutamic acid and imparts umami.
Green tea is an important accompaniment to many types of Japanese food. The constituent elements of the meal are often taken into account in selecting the type and quality of tea to be served. For example, in Japan one might choose the very mild and delicate gyokuro to go with sweet dishes and bean confections and the more bitter, roasted hōjicha before or after a meal. Maccha is powdered green tea whipped up in warm water and served in a large drinking bowl. This is how green tea was originally made, and maccha is still the focal point of the Japanese tea ceremony.
As we will see later, green tea and maccha can also be used in sweet dishes to create a good balance in relation to bitterness and umami.