The Japanese Table
Fermented Foods of Japan: Tsukemonoby Hisakazu Iino
Our ongoing feature series is all about seasonings, beverages and pickled foods made using a range of fermentation processes—foods that help define the special character of Japanese cuisine. In this third installment, we introduce pickles—tsukemono—which comprise a variety of foods and preservation methods.
The term tsukemono embraces a wide variety of pickles: fermented foods which, when preserved, offer distinctive flavors and qualities that are the direct result of the fermentation process.
Tsukemono are enjoyed as a traditional side-dish that can be found on the Japanese table throughout the year. These include cucumbers, eggplant, turnips and other vegetables in season. And while most tsukemono are vegetables, in some cases fish may be used as well. All are pickled in various mixtures, including salt, rice bran (nuka), miso, soy sauce, malt (koji), sake lees (sake kasu) and other ingredients.
Called ko-no-mono (“fragrant things”) or oshinko (“fresh aroma”), these standard side-dishes have been developed over time by the Japanese for their subtle flavors and refreshing taste.
Shio-zuke are ingredients pickled with salt and are quite common throughout Japan. They are made either by soaking vegetables in salt water, or by sprinkling salt directly upon the vegetables.
Those pickled in salt water are kept in an airtight container, and in this environment, the enzymes in the ingredients break down the food’s components into very different and flavorful substances.
The dehydration effect is more potent when vegetables are sprinkled directly with salt: in this process, a stone or other weight is placed upon a drop lid over the ingredients to assure uniform penetration of the salt, and to speed up the dehydration process. Since a certain amount of ventilation is needed, the color of these pickles may fade owing to oxidation.
Pickling with sprinkled salt requires regular attention, because moisture rises as it seeps out of the vegetables and pushes up the lid, and so the weight upon the lid must be adjusted to keep it secure. The best-known pickle of this kind in Japan is made with Chinese cabbage (hakusai), and is called hakusai-zuke.
The leading pickled food consumed mainly in eastern Japan is nuka-zuke, which is made by pickling vegetables in a nuka-doko—a bed of rice bran.
After each batch of pickles is made, the same pickling bed may be preserved and reused for long periods of time. Some bran-pickling beds have been used and handed down from generation to generation; some of these would be considered splendid examples of pickling beds from the microbiological point of view.
A bran-pickling bed is made by boiling a mixture of salt (measured at about ten percent the weight of the rice bran) and water (in amounts equal to the rice bran), then cooling and mixing it thoroughly with roasted rice bran.
The lactic fermentation process is started by adding a certain amount of bran from an older pickling bed. A nuka-zuke pickling bed has a distinctive flavor, and since the paste-like pickling bed is brown in color—appearing similar to miso—it is often called nuka-miso.
The pickling-bed must be mixed periodically by hand in order to nurture the bacteria within. This regular mixing and the use of good starter from an existing pickling bed are considered the secrets to making excellent rice-bran pickles.
Salt-pickled and rice-bran pickles have very different flavors and aromas, depending on how long the vegetables have been pickled. Asa-zuke (light pickles) and furu-zuke (ripe pickles) are distinguished by the duration of the pickling time.
Those ingredients pickled very briefly are called asa-zuke. Light pickling removes the raw or bitter essence of the vegetables through the workings of enzymes in the ingredients and these retain their original color and shape. Furu-zuke, those vegetables pickled for longer periods of time, absorb the effects of fermentation set in motion by the microorganisms, and thus have a mellow tang and distinctive aroma.
The quintessential Japanese pickle is the umeboshi, or salt-pickled plum. Umeboshi are famous for their anti-bacterial quality, and are often added to boxed lunches or inserted into onigiri rice balls not only for their taste, but to sustain freshness.
Umeboshi are made by first pickling the plums in salt and then sun-drying, adding the leaves of the red perilla, known as aka-jiso, to the brine to enhance color and flavor. There are many varieties of umeboshi, from bright pink soft-fleshed large ones to those that are very small and crunchy. Umeboshi have been made for over one thousand years, but the custom of adding perilla leaves to enhance color began in the seventeenth century.
Tsukemono were once made by hand in most households, but today most are made commercially. The majority of these are chomi-zuke, in which fresh vegetables are sliced and then soaked in a prepared pickling brine. These pickles are ready in a short period—the process takes only a half to one day. Compared to traditional pickles, these are much lighter in scent and flavor, and have become popular among people of all ages, especially the younger generation.
Despite their humble position as a simple side-dish, pickles have always been an essential part of every Japanese meal.
Hisakazu Iino was born in 1952. A 1975 graduate of the Tokyo University of Agriculture, since 1997 he has been a professor in the Graduate School of Science for Living Systems at Showa Women’s University. As a specialist in applied microbiology, Dr. Iino studies the interaction of human intestinal microorganisms. He also serves as an advisor to the Pharmaceutical Affairs and Food Sanitation Council, Ministry of Health, Labour and Welfare.