Japanese agriculture, forestry, fisheries and food

Highlighted Japanese IngredientWasabi

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Roots, stems, and leaves are all edible

Wasabi is a plant of the Brassicaceae family that originated in Japan. Grating its roots gives it a strong pungent flavor and aroma. It is enjoyed with foods like sushi, sashimi, and soba. Horseradish used as a condiment for roast beef also belongs to the Brassicaceae family. To distinguish the two, horseradish is referred to as “seiyo-wasabi,” meaning Western wasabi, and wasabi as “hon-wasabi,” meaning Japanese native wasabi.

Originally grown wildly in mountain streams in the deep mountains, wasabi began to be cultivated as an agricultural product over 400 years ago. Wasabi consists of: “sawa-wasabi” (water wasabi) cultivated in wasabi fields with access to water sources such as spring water; and “hata-wasabi” (field wasabi) cultivated in farms in cool mountain forests. Sawa-wasabi is primarily eaten by grating the roots, whereas with hata-wasabi the leaves and stems are eaten. While wasabi is often associated with the roots, the leaves and stems also have a unique, refreshing sharp flavor and aroma and are popular for processed foods such as Japanese pickles.

Made with clean, nutrient-rich water

　 Plenty of clear water is needed to cultivate sawa-wasabi. The ideal water temperature ranges from around 10°C to 15°C throughout the year. The ideal beds have sand or gravel that easily absorbs and drains water. Sawa-wasabi does not tolerate strong sunlight, making it a valuable agricultural product that can be cultivated only in limited areas.

Sawa-wasabi cultivated in sand-gravel beds is not eligible for Japan’s organic certification as it does not meet a criterion. Namely, Japan’s organic agricultural products must make use of the productivity of the agricultural land derived from soil. But because sawa-wasabi is cultivated using spring water that is rich in nutrients and flavor, and in environments where water is constantly flowing, sawa-wasabi can be cultivated using hardly any fertilizer and pesticides. Recent years have seen a rise in wasabi farmers cultivating pesticide-free sawa-wasabi. To protect it from strong sunlight, many sawa-wasabi fields have trees planted around them for the provision of shade.

Hata-wasabi, on the other hand, is cultivated in farms and is eligible for Organic JAS certification.

Globally Important Agricultural Heritage System

Shizuoka and Nagano Prefectures are two major producing regions of sawa-wasabi. These two prefectures combined account for over 90% of the sawa-wasabi production in Japan. The prefectures’ abundant spring water and moderate climate make them suitable as sawa-wasabi production regions. Iwate Prefecture has the largest production of hata-wasabi, accounting for 60% of the nationwide production.

In around the mid-Meiji period (1868–1912), Izu City in Shizuoka Prefecture developed a method for cultivating quality wasabi called “Tatamiishi (rock matting) style.” The city ships this wasabi nationwide and is the leading producer of wasabi roots in Japan.

Shizuoka Prefecture’s wasabi cultivating region preserves the traditional agricultural method of cultivating sawa-wasabi in terraced fields created from reclaimed swamps, using not fertilizer but nutrients contained in spring water. “Traditional WASABI Cultivation in Shizuoka” was designated a Japanese Nationally Important Agricultural Heritage Systems site by the Minister of Agriculture, Forestry and Fisheries of Japan in March 2017 and a Globally Important Agricultural Heritage Systems (GIAHS) site by the Food and Agriculture Organization of the United Nations (FAO) in March 2018.

Wasabi’s beneficial properties

A compound called 6-Methylsulfinylhexyl isothiocyanate (6-MSITC) can be obtained by grating the roots of wasabi. Studies have revealed that 6-MSITC has a variety of benefits, including acting as an antioxidant, helping with detoxification, improving blood flow, and inhibiting cancer. In addition, it is found to be good for the skin and is used in cosmetics and other beauty products. Incorporating wasabi into one’s daily diet will boost one’s health. Incidentally, most of these effects cannot be obtained from wasabi paste in tubes because it has been processed with the addition of other ingredients, such as hon-wasabi and horseradish.

The compound that gives wasabi its unique pungency when grated is allyl isothiocyanate (AITC). AITC is known to exert strong bacteriostatic effects against bacteria and mold and is used in various antibacterial and anti-mold products. The more finely the wasabi is grated, the more its cellular tissue breaks down and AITC forms. This gives the wasabi sharper pungency.

Wasabi’s potential

Long ago, wasabi was used to eliminate the odor of fish. It came into greater usage after it began to be put on hand-rolled sushi in the latter half of the Edo period (1603–1867). But this would not have come about, had it not been known that wasabi eliminates odor and prevents food poisoning by inhibiting the propagation of bacteria.

Wasabi has become well known now that sushi is a global staple. Nowadays, it is not unusual for wasabi to be served as a condiment not only for Japanese dishes but also for steak. Sometimes wasabi is utilized instead of horseradish for roast beef, and also as a secret ingredient for sauces and dressings.

With its unique pungency and invigorating taste, wasabi still holds potential for many more diverse cuisines beyond Japanese food.