Sikhye — Sweet Rice Drink and Nurungji Fermentation (식혜)

Sikhye appears in Joseon-era records as a court beverage and holiday drink; its enzymatic basis was understood empirically well before scientific enzyme characterisation

Sikhye (식혜) is Korea's traditional sweet rice beverage — cooked rice saccharified by yeotgireum (엿기름, malted barley water) at controlled temperature, producing a naturally sweet, faintly rice-flavoured drink with floating grains. The process is enzymatic: alpha and beta amylases from the malted barley convert rice starch to maltose over 4–6 hours at 60°C. When the rice grains float to the surface, saccharification is complete. The drink is then boiled briefly to stop enzyme activity, chilled, and served with a few floating pine nuts or jujube. Sikhye represents one of the oldest examples of controlled enzymatic fermentation in Korean food culture.

• Parallels Japanese amazake (甘酒, sweet rice koji drink) in principle — both use enzymatic saccharification to produce naturally sweet, low-alcohol rice beverages — and the Korean makgeolli brewing tradition begins with the same enzymatic step

Sikhye is the traditional post-meal sweet drink of Korean formal occasions (설날, 추석) — its natural sweetness, clean rice flavour, and digestive properties make it a more culturally resonant alternative to commercial beverages. Served ice-cold, it functions as Korea's original soft drink.