Fermented Tofu Skin

霉千张 is anchored to Songxia (崧厦) township in Shaoxing's Shangyu district. Local records and the official intangible heritage documentation trace its origin to the Cai Wansheng water-works (蔡万盛水作坊), active in the Qing dynasty approximately 200 years ago. The proprietor Wang Shaorong had produced a large batch of thousand-layer tofu skin for local temples; the excess, covered and set aside, was found the following day mottled with yellow spots and smelling of mould. Unable to waste the surplus, he tasted one sheet and discovered unexpectedly pleasant softness and flavour. The three great monasteries of Putuo Island — 普济, 法雨, and 慧济 — soon began dispatching representatives to Songxia to purchase 霉千张 for monastic feasts. Tradition also holds that the Qianlong Emperor praised it as a rare delicacy during his southern tours, though this attribution is difficult to verify independently. In November 2008, the Songxia 霉千张 craft was inscribed on the second batch of Shaoxing City intangible cultural heritage.

The fermented skin is yielding and almost unctuous — the mould has dissolved the tough soybean protein network into something softly giving. A mild acidity counters the richness, and the aroma walks a fine line between cheese-ripe and ammonia; steaming deepens the savory dimension considerably.

Mucor and related filamentous fungi colonize the rolled soybean sheets during the 2–3 day fermentation. Their extracellular proteases cleave the soy glycinin and beta-conglycinin protein networks — the structural scaffold that makes fresh tofu skin tough — into shorter peptides and free amino acids including glutamate, producing soft texture and savoury depth simultaneously. Mould lipases hydrolyse the soybean's linoleic-acid-rich oils into free fatty acids, yielding cheese-like aromatic compounds responsible for the dish's characteristic ripe aroma. The white mycelium visible on the surface is edible and contributes to the final texture.