The foods we eat daily sometimes have a unique umami: Japanese kombu soup with katsuobushi, Chinese chicken soup with chives or cabbage, Scottish leek and potato soup, and Italian cheese and mushroom sauce. Why do these combinations lead to a surge in umami? It's all thanks to umami amino acids and umami nucleotides.
In 1908, Professor Kikunae Ikeda of Japan first discovered that umami is a "pleasant and delicious taste" formed by umami amino acid salts and umami nucleotides. Our first experience with umami in life comes from breast milk—the combination of umami amino acids in human milk is very similar to that in chicken soup. There are many types of taste amino acids; for example, glycine and alanine have a sweet taste, aspartic acid and glutamic acid have a sour and umami taste, and valine, phenylalanine, tyrosine, and leucine have a bitter taste. Bitter-tasting amino acids, when appearing alone, are not pleasant, but when combined with sour and sweet tastes, they can form special flavors.
Meats such as chicken are rich in umami nucleotides. When cooked with foods rich in glutamate (such as cabbage, celery, carrots, tomatoes, etc.), an umami synergy occurs, and the overall "umami" of the dish is greatly enhanced. Even a small amount of umami ingredients can produce a great effect, a method many chefs call an "umami bomb."
Tomato is the "spokesperson" for umami amino acids. Any soup stewed with it is exceptionally delicious. In addition to the sweet and sour taste and color of the tomato itself, the high content of umami amino acids in tomatoes—aspartic acid and glutamic acid—also plays a significant role. Tomatoes taste most umami when ripe and are best for stewing soup.
In addition to adding a small amount of tomato to the soup, what other options can be used to enhance the umami? There are many foods rich in umami amino acids and umami nucleotides: fish, shellfish, cured meats, mushrooms, cabbage, spinach, celery, chives, asparagus, carrots, fermented dairy products (yogurt, cheese, etc.), soy products (soybeans, miso, broad bean paste, etc.), pickled foods (kimchi, etc.), and green tea.
When stewing meat, adding tomatoes, cabbage, celery, carrots, chives, or green tea will significantly enhance the umami.