Objects of Desire: Sumo/Dekopon

The Sumo is an exciting new hybrid of Citrus with an interesting story. Sadly it is yet to come to NZ in either fruit or tree form but i am very eager to try. From all accounts though, it seems to be a prized fruit at the high end of the Citrus market.

Its story begins in 1972 on Kyushu Island in Japan. A citrus grower there set out to develop a fruit which would combine the best of the easy-to-peel Japanese Satsuma with the big, juicy, sweet oranges from California. It is specifically a hybrid between a Kiyomi Tangor and a Ponkan. Although he saw promise in an obscure tangerine-orange hybrid, this new fruit was challenging to grow. Thankfully, the grower persevered. Over time, he developed a series of methods for growing, pruning and thinning his trees, which is different from all other citrus.

It took over 30 years but his hard work was rewarded when recently, this new variety became the most prized citrus fruit in Japan and Korea.  Following the Japanese tradition of offering the best fruit as a gift, one can find it in Tokyo gift shops, selling for up to US$10 for a single piece of fruit!  Now this legendary fruit, which is called Dekopon in Japan and Hallabong in Korea, is available in America.

Sumo is the biggest mandarin you'll ever seen. It has a distinctive shape with a prominent "top-knot" or large protruding bump on the top of the fruit. The peel is bright orange, bumpy and loose so it peels effortlessly, usually all in one piece! The delicate sections separate easily. Sumo has very little albedo (the white part of citrus), allowing the fruit to section easily with less of the white "netting" sticking to the fruit. It is avalible in stores in very limited supplies available from February-May in the U.S. It's seedless, juicy without being messy, and one of the sweetest of all citrus with very low acid.

At the beginning of the harvest, the fruit is very high in acidity. Consequently growers use a secret Japanese storage method to "cure" the fruit, to reduce its tartness. But with full maturity, after the three weeks curing in vinyl pouches, sugar rises and acidity drops naturally. Dekopons measured 13-18 degrees Brix (a measure of sugar content), numbers that mean powerhouse flavor. (Typically, other commercial citrus varieties such as navel oranges and clementines average 11 to 13 degrees.)
Hopefully this variety will become available soon in NZ. It has only just been released in the US in the past year under the name Shiranui after much cloak & dagger with budwood quarantine procedures from Japan. The Citrus nurserys here i've talked to haven't heard of it yet and have mentioned it is quite difficult to import new budwood into NZ. 

  

Photos courtesy of Susan Broman and Shizuoka Gourmet

Photo: Oli Studholme