Natto: Originated in ancient China, it has been made since Qin and Han Dynasties. Soybean is fermented by Bacillus natto to make bean products, which are sticky, smelly and slightly sweet. They not only retain the nutritional value of soybeans, but also produce a variety of physiologically active substances in the fermentation process, which have the functions of dissolving fibrin in the body and regulating physiological functions.

Traditional method: wrap steamed soybeans with straw. Straw needs to be soaked in boiling water at 100 degree for sterilization and kept at 40 degrees Celsius for one day. Bacillus subtilis natto, which is common on rice straw, can produce spores and has high heat resistance, so the sterilization process is not destroyed. High temperature culture is fast, which can inhibit other strains and ferment soybeans. Fermentation will produce coarse silk, which mainly comes from glutamic acid in the composition and is considered as the source of natto's delicious taste.