Li Fermented Fish (Yu Cha)

The Li people, descendants of the Baiyue ethnic groups, migrated to Hainan Island approximately 3,000 years ago from Lingnan, bringing preserved-fish traditions with them. The dish was originally called yúzhǎ — a term documented by Eastern Han lexicographer Xu Shen in the Shuowen Jiezi (circa 100 CE) as 'the preservation of fish.' As the Li dialect pronunciation reached the wider coastal and inland Han population, the name shifted phonetically to yú chá (fish tea), losing all connection to the drink. Folk accounts attribute the dish's accidental invention to a post-harvest feast where leftover cooked rice and raw fish were sealed together and emerged days later transformed into a delicious fermented food.

A small spoonful delivers a jolt of sour funk followed by a lingering salty sweetness — the fish flesh softened almost to a melt, the fermented rice clinging in warm starchy clusters, the whole thing dissolving into an umami warmth that builds over seconds. Locals say it takes three tastes before the addiction sets in.

Fermentation is driven primarily by Lactobacillus plantarum and L. pentosus, which together account for over 68% of the microbial community by gene copy number, according to a 2017 peer-reviewed microbial diversity study of Li ethnic fish tea from Baisha and Baoting counties. These homofermentative bacteria consume cooked rice starch, producing lactic acid that progressively lowers the jar pH and suppresses spoilage organisms, while fish proteins are hydrolyzed into free amino acids. The 3–5% salt concentration draws moisture from the fish via osmosis, creating a self-basting brine that further inhibits pathogenic bacteria. Research identifies the empirical optimum fermentation period as 18 days, when total acid content stabilizes and free amino acids peak.