USUKI, Oita - Kabosu citrus fruits are often served with grilled fish and tempura. The green fruit, grown in the summer sun, gives off a refreshing aroma and mild tartness.
More than 90 per cent of kabosu in the nation are produced in Oita Prefecture. I visited Usuki in the prefecture, known as a major producer of the fruit, in mid-August during the peak of the harvest.
Takayoshi Mine, 64, who has been growing kabosu for about 40 years, was removing them from the branches one at a time with scissors in a hillside orchard in a mountainous area. As their branches have thorns, gloves are a must when cutting them free.
"Though I'm happy harvesting, I can't stand the heat," he said as sweat rolled down his forehead.
A heat wave after this year's rainy season has led to a splendid crop, according to Mine. Farmers are busy harvesting in August and September, when the fruits are still green before ripening and turning yellow.
When I touched a five-centimeter fruit, it felt like a golf ball. The dark green colour was beautiful. As sunlight is needed to bring out such colour, cultivation of kabosu requires efforts such as thinning out the fruit and the leaves.
At a fruit-selecting facility operated in the city of Tsukumi by JA Oita, a local agricultural cooperative, Yasuaki Ninomiya, 31, gave me a kabosu halved with scissors. Saying, "This is a good way to try it," Ninomiya tilted his head upward, opened his mouth and squeezed the halved fruit into his mouth all at once. I bit the citrus fruit the same way and felt the juice spread into my mouth. Though I said, "It's sour," I also tasted a hint of sweetness with a fresh scent.
Kabosu can be used the same way as a lemon. The juice is added to seasonings and sprinkled on dishes. As the sourness is not incredibly strong, kabosu can bring out the taste of other ingredients without spoiling their original flavors. They also contain lots of citric acid and vitamin C.
The cultivation of kabosu in Usuki is believed to date back to the Edo period (1603-1867), during which a doctor brought a sapling from Kyoto and planted it in the city, according to the Usuki city government. Local people grew the plants at home and burned kabosu rind to ward off mosquitoes. One likely explanation of the name "kabosu" is that it derives from "ka-ibushi," which means smoking out mosquitoes.
The Oita prefectural government started to encourage cultivation of kabosu in the 1960s, which made it a local specialty. The prefecture's production volume in fiscal 2014 was estimated at about 5,660 tons. Drinks with the citrus juice are gaining popularity these days, and there is a growing demand for the fruits for processed products.
Increasing consumption outside the prefecture is an issue to be tackled. In the prefecture, people add the juice to dishes such as sashimi, fries and miso soup, and the alcoholic beverage shochu.
"My body is made of kabosu," Mine quips.
However, of the products shipped from the JA agricultural cooperative, only about 20 per cent are bound for the Kanto region, about 10 per cent for the Kansai region, and almost the entire remainder stays within the Kyushu region.
Ninomiya says, "Our rival is sudachi."
Sudachi, another type of Japanese citrus fruit, is smaller in size than kabosu and has a different smell. However, some people mistake kabosu for sudachi as the colors are very similar.
Some members of a local kabosu promotion association, including Ninomiya, will visit the annual sanma saury festival held later this month in Meguro Ward, Tokyo, to provide kabosu there.
"I hope to publicize the charms [of kabosu], which plays an excellent supporting role" for dishes, Ninomiya said.
For best results when trying to extract the juice from a kabosu, halve the fruit crosswise and then cut it into wedges. Hold the wedge with the rind facing downward before squeezing the juice onto food or into a container. You can enjoy not only the juice, but also the essence of the aroma contained in the rind.
When the whole fruit is put into a sealed plastic bag and kept in a fridge, it will keep fresh for about a month. According to Ninomiya, if kabosu juice is frozen in an ice cube tray, it can be preserved for a long time and conveniently used in small portions.
The kabosu promotion association's website introduces recipes that use kabosu at www.oitakabosu.com