Kabosu is an evergreen tree with broad leaves, part of the Rutaceae family, which produces a fruit similar to a citrus. The scientific name of the plant is Citrus sphaerocarpa. The kabosu fruit is widely used in Japan. Its juice is a key ingredient in many local recipes, from sashimi to fish and hot pots.
The juicy fruit of the kabosu tree is very similar to another Japanese variety, the yuzu. The juice can be compared to the one of a regular lemon and it replaces vinegar in a number of local dishes. The plant that produces the fruits is small in size and looks like a thorny shrub or small tree. The fruit is yellow when ripe but it is normally harvested while still green. The apex has a specific donut shape after the pistil falls off, which is helpful in distinguishing it from other similar citrus fruits such as the sudachi.
The fruit of kabosu is spherical, with a diameter of about 2 inches. It can be consumed at any time, when it is ripe and yellow or when unripe, with a lime green color. The rind is normally smooth but it can be slightly irregular, while several seeds are located inside the yellow pulp. The taste of the fruit has been compared to a mix of mint, lemon and melon. Like all citrus fruits, it is sweet and acidic at the same time.
Kabosu are quite rare and hard to find in Japan, where they are only harvested in the prefecture of Oita. The fruit is very similar to a lime. It is probably a hybrid of several species, the Ichang papeda crossed with either a sour orange or a mandarin. It is similar to the yuzu and the sudachi, which are other varieties of citrus found in Japan.
The origin of the plant is in China, where kabosu can be found growing in the wild. The fruits are green, with the distinctive sweet and sour taste of lemons. It was imported and naturalized in Japan from China during the ancient Edo period and it has become an ingredient of both Chinese and Japanese cuisine. Kabosu is normally used as a vinegar replacement in Japan, being especially well-suited for fish dishes.
While the kabosu is very similar to the yuzu fruit, its rind is thinner and it has a lower number of seeds and less pith. Just like a lime, the kabosu is useful even when unripe and can be harvested for its juice. If left to ripe on the tree, the fruit eventually turns yellow. Similar to the yuzu, it can be consumed both green and yellow. While the yuzu has more flesh, the kabosu is richer in juice, which is very useful in cooking and makes the fruit more valuable. The kabosu is a great garden plant because of the versatility of the fruit, which provides amazing taste and fragrance.
The kabosu has a similar taste to its citrus relatives like the yuzu, lime and regular lemon. Almost the entire production, about 98%, happens in the Oita prefecture of the island of Kyushu in the South of Japan. It is difficult to find in other areas of the country. According to the myth, a doctor from Kyoto got a branch from China during the Edo period and planted it in Oita for the first time.
Kabosu is very rich in vitamin C, just like any other citrus fruit. It is usually turned into a vinegar substitute, which is said to have important health benefits. Oita locals believe that it can balance blood pressure and cure liver diseases. The juice also has strong antiseptic properties and can kill bacteria, being especially potent against throat infections of any kind.
The locals also use the kabosu fruit juice to cure a variety of hair issues. They believe it can treat any problem of the hair and scalp, like premature hair loss or dandruff. The juice is applied directly on the scalp. Besides its curative properties, the juice also improves the look of the hair, restoring its normal shine.
Because of its ability to kill bacteria, kabosu juice is also effective when applied on other areas of the skin. It can provide relief in many situations, from stings of bees or other insects to sun burns. It can also remove acne and treat skin diseases such as eczema. It is also known to reduce wrinkles and eliminate blackheads, restoring the glow of the skin and fighting the effects of aging. The juice can be included in the daily diet, prepared with honey and water.
The kabosu fruit also has important antioxidant properties and can neutralize the free radicals that damage the skin and lead to wrinkles, lines and other signs of aging. This is because of the high content of flavonoids and vitamin C.
The antioxidant effects are not limited to the skin and have wider benefits for the immune system. They have an impact on many diseases, in particular by reducing the levels of cholesterol and improving heart health. The kabosu juice is also good against rheumatoid arthritis, ulcers, respiratory diseases, kidney stones and even some types of cancer.
In Japan, the kabosu is praised not only for its health benefits and edible fruit. It has other uses as well, for example the dry peel can repulse insects if burned. The kabosu is also a valuable ornamental plant.
The kabosu fruit juice is extremely sour but it has a special aroma. Its main use in Japanese cuisine is as a more fragrant alternative to vinegar, the juice is also an ingredient in grilled fish, hot pot ponzu and sashimi. It has more culinary uses in the Oita Prefecture where it can be found in large quantities, where it is considered a general flavour agent as well as part of noodles, shochu and miso soups. It is normally squeezed after cutting the fruit in quarters, with the peel down to stop any seeds from reaching the food. The juice is an ingredient in many products like non-alcoholic beverages, frozen desserts, snack foods, condiments, juices, alcoholic drinks, wagashi or pastries.
In cooking, the kabosu can replace the regular lemon in any recipe. Its juice can be added on top of dishes and sprinkled to improve the taste. Since it is not very sour, kabosu juice doesn't cover the taste of other ingredients but actually makes them more intense. It is extremely rich in vitamin C and citric acid.