Douchi can not only stimulate appetite, promote digestion, dispel wind and cold, but also prevent cerebral thrombosis and Alzheimer's disease. The basic method of douchi is to steam soybeans or black beans and put them into a ceramic pot for fermentation. From the appearance, there are two kinds of black and yellow lobster sauce. At present, black fermented soybean is used in Hunan cuisine in Sichuan and Guangdong, which is thin, strong, salty and slightly bitter. In addition to being directly used in vegetables, almost all canned foods are also made of black lobster sauce. Black lobster sauce is most suitable for cooking, such as fried green pepper and bacon with lobster sauce, fried spinach with lobster sauce, braised fish with lobster sauce and fried oysters with lobster sauce. The fermented soybean basically keeps the original color and prototype of beans, and has no taste except salty taste. It can be eaten directly, added with chili pepper or sesame oil, and processed into other fermented bean products. Douchi also contains a variety of nutrients, which can improve the gastrointestinal flora. Eating lobster sauce regularly can also help digestion, lower blood pressure and improve the detoxification function of the liver. Older people can eat more food every day, especially patients with thrombosis, because experts from the Japanese Institute of Geriatrics have found that eating lobster sauce often can prevent cerebral thrombosis. The cobalt content in douchi is 40 times that of wheat, which has a good effect on preventing coronary heart disease. Douchi also contains a large amount of urokinase which can dissolve thrombus, which is very effective in improving cerebral blood flow and preventing and treating Alzheimer's disease. No matter how good the lobster sauce is, the elderly can't eat more, and it is advisable to eat less than 50 grams a day. Moreover, a large amount of salt will be added during the processing of lobster sauce, so if lobster sauce has been added to dishes, the amount of cooking salt should be reduced to avoid excessive salt intake, thus reducing the risk of hypertension, heart disease and stroke.