The diversity of Japanese citrus fruits, in season from fall to spring

Citrus fruits, which originated in Southeast Asia, centered on the Assam region of India, made their first appearance in Japan’s history about 1200 years ago, dating back to the mythical era. The “tachibana," recorded in the archaic texts Kojiki and Nihon Shoki as brought back from China as the fruit of immortality and longevity, is believed to be the progenitor of the mikan (mandarin) citrus tree found all over Japan today. Ever since, Japanese citrus fruits have developed in a variety of sizes, shapes, and tastes, winning broad popularity throughout Japan's long history.

Another interesting feature of the Satsuma mandarin is that its name and flavor both change depending on time of harvest. Those harvested from September to October are called gokuwase, boasting juicy flesh and slightly stronger tartness. Those harvested from late October to December are called wase, and are sweet with milder tartness. Those harvested from late November to late December are called nakate, and are powerfully sweet with less tartness. Those harvested from late December to March are called okute, and are richly sweet with moderate tartness. These seasonal changes are another reason why Japanese citrus can be enjoyed in such a wide variety of flavors.

Among the citrus fruits unique to Japan, aromatic citrus fruits play an undeniably important role. Unsuitable for eating raw, these citrus fruits—including yuzu, kabosu, sudachi, and more—usually have powerful acidity and are enjoyed more for their aromatic fragrance. They are often used in Japanese cuisine, generally as condiments or seasonings. Typically, the citrus juice is squeezed onto grilled fish or into soup or the zest is added to give food a sharp, refreshing aroma, accentuating the flavors. Aromatic citrus fruits are produced all over Japan, but principally in Kyushu and Shikoku, and the size of the fruit, the mildness of the acidity, and the fragrance can all differ markedly.

Yuzu, perhaps Japan’s most prominent aromatic citrus variety, has a wide variety of uses and has won attention not only in Japan but also internationally. Particularly in Europe, it is added to sauces for French meat and fish dishes to add unique acidity and aroma, mixed into salad dressings, and features in desserts such as macaroons, cakes, or chocolates made with yuzu zest or juice. Yuzu has a characteristically sharp, slightly bitter taste. Mixed simply with carbonated water, it becomes a refreshing, appealing drink.
It is also customary in Japan to float whole yuzu fruit or yuzu peel in a hot bath during the winter, its season of harvest. The resulting “yuzu bath” has long been known to promote blood circulation and warm up the body. The unique fragrance of yuzu has a powerful relaxing effect, and it is often used as an aromatic oil. Yuzu offers a great deal of potential in terms of its soothing, healing power.

How was such diversification of Japanese citrus fruits achieved? The reason is closely related to Japan's abundant four seasons and warm climate. In Japan, the year is divided into four seasons—spring, summer, fall, and winter—and for agricultural produce such as fruits and vegetables, every product has a season in which it is considered most delicious. Citrus fruits, which prefer warmer, sunny environments, are cultivated in western Japan and on the Pacific coast. Most citrus varieties, which put out white blossoms in spring, bear green fruit during the harsh summer months, and grow plump and juicy from fall into winter, their peel turning bright orange or yellow as they reach the harvest season, are in season from fall to spring (November to March). Along with the simple joys of the four seasons, the real thrill of Japanese citrus fruits lies in enjoying all the variations and flavors as they come into season.