Bean curd is a kind of soybean food that has been fermented by microorganisms and created by the working people in ancient China. As early as the 5th century AD in the Northern Wei ancient books, there is a record about the production process of fermented bean curd. For thousands of years, fermented bean curd has been loved by people.

Modern scientific research shows that a variety of microorganisms are involved in the fermentation of tofu, such as penicillium, yeast, aspergillus, and mucor, among which the main role is mucor. Mucor is a filamentous fungus, widely distributed, commonly found in soil, fruits, vegetables, and grains. Mucor grows rapidly, with developed white hyphae. Proteases produced by microorganisms such as Mucor can break down the protein in tofu into small molecule peptides and amino acids; lipase can hydrolyze fat into glycerol and fatty acids. Under the synergistic effect of various microorganisms, ordinary tofu transforms into a unique flavored bean curd.

Mucor hyphae

Tofu covered with mucor

In the process of making fermented bean curd, the preparation of braised soup is also critical. Braised soup is directly related to the color, aroma and taste of the bean curd. Braised soup is prepared from wine and various spices. The wine in braised soup can be cooking wine, rice wine, rice wine, sorghum wine, etc., the content is generally controlled at about 12%. Adding wine can inhibit the growth of microorganisms, and at the same time can make the fermented bean curd have a unique flavor. There are many types of spices, such as pepper, pepper, star anise, cinnamon, ginger, chili, etc. Spices can modulate the flavor of fermented bean curd and also have antiseptic and sterilizing effects.