Nigari Tofu Making Coagulation Science

Japan — tofu introduced from China 8th century; Japanese refined technique and developed specific coagulant varieties and textures over centuries

Tofu making requires precise understanding of the coagulation process — hot soy milk (tonyu) is treated with a coagulant that causes the soy proteins (primarily glycinin and beta-conglycinin) to form a gel network. The traditional coagulant is nigari (苦汁, bitter water) — magnesium chloride extracted from seawater during salt production. Different coagulants produce different tofu textures: nigari creates irregular curds with slightly mineral character (traditional flavor); calcium sulfate (石膏, sekko) creates finer, smoother, whiter tofu (the standard silken variety). The temperature of soy milk at coagulation (75-85°C) and stirring technique determine curd size and final texture.

• Chinese douhua uses same coagulation principle — calcium sulfate for silky fine texture parallels Japanese kinugoshi tofu → Douhua (tofu pudding) calcium sulfate coagulation Chinese
• Both are protein coagulation products — Indian paneer uses acid (vinegar/lemon), Japanese tofu uses salt coagulant; different protein, same precipitation principle → Paneer acid coagulation from milk Indian

Pure soybean protein with subtle mineral character from nigari — fresh tofu has delicate sweetness that deteriorates within hours of making