Yuja (Korean Citron)

Yuja is a hardy citrus usually traced to China's Yangtze region; a popular legend credits the Silla-era maritime trader Jang Bogo with bringing it to Korea. It is an evergreen shrub with long thorns that flowers white in June and ripens in autumn. The Encyclopedia of Korean Culture notes that it cannot tolerate hard cold, so it is grown only along the coasts of South Gyeongsang and South Jeolla, in sunny spots sheltered from northwest winds.

Geoje Island was long the best-known producer. A local Geoje newspaper traces cultivation there back to the 15th century and recalls that a few trees could pay a child's university fees, earning yuja the nickname ‘university tree.’ From the 1980s, grafted seedlings from Geoje nurseries spread widely to Goheung in South Jeolla, and Goheung became the country's leading yuja county; the same report cites 2019 figures putting it at roughly two-thirds of national production. The harvest peaks in November.

Because the fruit has little flesh, lots of seeds and a very aromatic peel, it is used whole. The Encyclopedia of Korean Culture describes the classic method: slice the fruit thinly, pack it with honey or sugar in a jar, and leave it in a cool, dry place for two to three weeks until clear syrup collects. A spoonful of this yuja-cheong stirred into hot water, sometimes topped with pine nuts, is yuja-cha. Yuja also flavors hwachae, sweets and dressings.

• Vitamin C in the peel: Whole raw yuja is rich in vitamin C, much of it in the peel, which is why the fruit is preserved whole.
• Traditional winter drink: Yuja-cha has long been drunk in cold weather and is traditionally believed to soothe colds and aid digestion; these are traditional beliefs rather than proven effects.
• Sugar in the syrup: Per 100 g, yuja-cheong is mostly sugar (about 59 g in the Korean table). A spoonful in tea adds noticeable sugar; people watching sugar intake should use it sparingly.
• Citrus sensitivity: People with citrus allergies or sensitivity to acidic foods should take care.