Stinky tofu is made from soybeans, and its production process is complicated. Soybean goes through ten processes: screening, hulling, soaking, grinding, filtering, boiling, removing spots, forming, slicing and fermenting. Stinky tofu is "smelly" because in the process of fermentation, pickling and post-fermentation, protein contained in tofu is decomposed by protease, and sulfur-containing amino acids are fully hydrolyzed to produce a kind of hydrogen sulfide (H2S). Amino acids produced after decomposition in protein are delicious, so they are "delicious".