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After Buddhism was introduced to Japan around the seventh century, the diet became largely vegetarian, based on rice accompanied by side dishes of vegetables. But in many regions, fresh vegetables were not always available in every season - and so pickles, known as tsukemono, ensured a steady year-round source of vegetables.

Japan is surrounded by ocean, and it is likely that the first pickling agent was sea water. When seasonings like miso soybean paste, soy sauce and vinegar were developed, these were also used for pickling, creating a more abundant variety of tsukemono. The saying, "Nani wanakutomo ko no mono" (there may be nothing else, but as long as I have pickles . . . ) aptly expresses the general sentiment that, even though there may be nothing else on the table but rice, one can still enjoy a good meal with tsukemono. And so, from the seventh to the nineteenth centuries, tsukemono were truly an essential part of the Japanese diet.

Vegetables pickled in miso or soy sauce can be found not only in Japan, but in China and other Asian countries. Those vegetables pickled in rice bran (nuka-zuke), sake lees (kasu-zuke) and koji yeast (koji-zuke), however, are unique to Japan.

Nuka-zuke are made by pickling vegetables in a paste of rice bran (kome-nuka) and salt. Rice bran is the brown outer layer of the rice kernel, routinely discarded when rice is polished. Japan is the only country that pickles vegetables in rice bran; even other rice-eating countries like China or Indonesia have not developed this preservation method. Bran is rich in vitamins B1 and B2 - and so, therefore, are the vegetables pickled in this healthy mixture. The best-known rice bran pickles are takuan-zuke and nuka-zuke.

Kasu-zuke are vegetables pickled in sake lees, the residue produced when fermented rice is pressed to make sake. Kasu-zuke have a high alcohol content and alcohol smell. Koji-zuke are vegetables preserved in koji yeast. They absorb the amylase produced by this yeast and are known for their sweet flavor.

Varieties of Tsukemono

Tsukemono reflect the local characteristics of the areas where they originated. Many are popular regional specialties that are often given as gifts. Here is a list of some of Japan's best-known tsukemono:

Takuan-zuke: Made of pickled dried daikon in rice bran and salt, takuan-zuke are the leader of all tsukemono. One theory suggests the name derives from Takuan, a Zen Buddhist who lived in the early 17th century, thought to have invented the rice-bran pickling paste.

Nuka-zuke: Rice bran and salt water are kneaded into a paste and left to ferment, producing lactic acid. Fresh vegetables are placed overnight in this pickling bed then removed, rinsed and cut for serving. Once prepared, nuka paste can be re-used over and over. Until recently, a tub or crock of nuka paste for pickling could be found in nearly every kitchen.

Umeboshi: Made by soaking unripe Chinese plums in brine and leaving them to mature. Umeboshi are often packed with red shiso leaves for flavor; thus the red color of the plums.

Umeboshi contain a lot of citric acid, which destroys pathogenic bacteria. Once absorbed by the body, the citric acid turns alkaline, thus stimulating blood flow. Thus umeboshi are becoming quite popular as a health food.

Fukujin-zuke: Made from finely chopped daikon, eggplant, cucumbers and other vegetables,fukujin-zuke are a popular condiment with Japanese-style curry, mimicking the chutney served with Indian curries.

Teppo-zuke: The ends of shiro-uri, oriental pickling gourd, are sliced off and the seeds removed to create a hollow tube. Stuffed with red peppers, the shiro-uri is then marinated in soy sauce. This pickle, a specialty of the area around Narita airport near Tokyo, takes its name from the long, thin shape, like the barrel of a rifle (teppo) .

Miso-zuke: This category includes various vegetables pickled in miso soybean paste. The flavor of the miso penetrates the vegetables, which can be preserved for a long time using this method. The miso-zuke process is over 1,000 years old and is one of the most common pre-servation methods in Japan.

Nara-zuke: Refers to various pickles made with sake lees; the most commonly used ingredient is shiro-uri. The alcohol in sake lees is a potent preservative. This method, also over 1,000 years old, developed along with the sake brewing industry. Nara-zuke are considered a luxury item.

Bettara-zuke: Daikon preserved in koji yeast and sugar is a favorite among those with a sweet tooth. A Tokyo specialty, this pickle was developed about 200 years ago.

Senmai-zuke: Giant turnips that measure as much as 15cm in diameter are sliced very thin and marinated in a sweet vinegar mixture. This Kyoto specialty tastes delicious with bread.

Na-zuke: Various types of leafy vegetables such as bok choy, pickled with salt.

Healthy Tsukemono

Tsukemono are loaded with nutrients; by simply salting fresh vegetables, it is possible to reduce their bulk and make them tastier, without greatly reducing their nutritional value. Tsukemono are a good source of fiber, calcium and potassium. Lightly pickled vegetables are also rich in vitamins A and C. Even though salting makes them less bulky, they contain the same amount of fiber.

Vegetables preserved in rice bran contain three to five times more vitamins B1 and B2 than those that are fresh. These water-soluble vitamins leach out of the bran and penetrate the vegetables.

Many tsukemono are made through the fermentation of lactic acid. Varieties made using rice bran and lightly salted types develop more flavor through fermentation. The lactobacillus in tsukemono play a role in regulating the flora of the gastrointestinal tract and the lactobacillus itself is thought to help prevent cancer. A variety of seasonings are added to the different tsukemono described above, and some contain oils with medicinal properties.

Changing Tsukemono

Today, tsukemono are changing as people seek healthier, more natural foods. Most tsukemono are produced by salt preserving, and some 20 years ago, many pickles had a salt content of over 8%. Today it is possible to make tsukemono with as little salt content as 3% - 4%, even for long-term preservation.

Tsukemono are now made with fewer artificial additives, and care is taken to enhance their original color, gloss and flavor. Natural coloring agents have largely replaced artificial colorings, and most tsukemono are now kept in cold storage or are heat-sterilized. Tsukemono, once a form of preserved food, is nowadays often considered a prepared food. Efficient refrigerated transport and facilities have contributed to the higher consumption of lightly preserved tsukemono, compared to the more heavily preserved types.

More imported ingredients, including Chinese greens and Western-style vegetables, are also being used. New varieties have been developed to eat with bread or noodles, and to enjoy just for snacking. In the quest for more healthful tsukemono, red pepper, garlic and many other different seasonings are being used to compensate for lower salt content - and to enhance flavor.

Author's Profile

Toshio Ogawa is head of the Tsukemono Kenkyujo (Tsukemono Research Institute) and advisor to the Zen-Nihon Tsukemono Kyodo Kumiai (All Japan Tsukemono Cooperative Association). Now retired, he lectures at the Tokyo University of Agriculture and Technology and serves as a technical consultant. He has written many books on tsukemono.