Mucor is a genus of fast-growing fungi of the class Zygomycetes that occur on vegetable matter, soil, and dung. Mucor racemosus and Mucor mucedo may be responsible for spoilage of bread and meat, while other species may be parasitic on stored grains. Some species are put to deliberate use: Mucor hiemalis is used in the production of sufu, the Chinese fermented tofu, and Mucor racemosus and Mucor rouxianus are used in the production of pozol, the Mexican fermented maize beverage. Their rapid growth and strong lipolytic and proteolytic enzymes make them both feared spoilers and valued fermentation organisms, depending on context.