Fermentation has been utilized to prepare tasty and healthy foods for a long time in China. Chinese people started to realize the benefit of fermented food to human health a long time ago. Some of the typical fermented foods are pickles made from some vegetables, and vinegar and alcohol made from grains. Fermentation has been widely used to prepare soybean products. Popular fermented soybean foods in China are sufu (fermented tofu), douchi (fermented soybeans), soy sauce, and fermented soymilk. Sufu and douchi had become parts of the Chinese meal at least 2,000 years ago2,26 . Douchi was found in the artifacts from the Tomb of West Han Dynasty of Mawangdui, Hunan province33 .
The contents of vitamin B12, which is essential for the nervous system, in Chou sufu (strong smell sufu) and red sufu produced in Beijing were determined. Vitamin B12 contents were 9.8-18.8 mg/100 g in Chou sufu and 0.42-0.78 mg/100 g in red sufu27 . Therefore, it was shown that the Chou sufu had not only a strong smell but a high amount of vitamin B12 , possibly because of high activity of microorganisms during fermentation.
According to, commercial sufu contains 1.7-22 mcg B12 pr. 10g fresh weight.