1, soaked in cold water in advance is easy to rot quickly. Poor cooking of black beans easily affects the taste. Usually we can put black beans into the pot in advance and soak them all night. If it is summer and the temperature is high, we can soak them in the freezer of the refrigerator. After soaking, we can wash the black beans, put them in a pot and cook them with high fire, remove the floating foam in the pot, and then simmer them with low fire, so that the black beans in the pot can be boiled easily.

2. Black beans are produced all over China. China is rich in black bean resources and has a wide variety, and some rare black bean varieties are still used in production. For example, Jiangsu Taixing black bean is an early-maturing spring soybean in the Yangtze River basin, with early maturity, high yield and strong adaptability, and it is still the control variety of the southern early-maturing spring soybean group in the national soybean regional test. Dandong medicinal black bean is Qing Zi leaf black bean, with large grain, excellent variety and high nutritional value. The fragrant black broad beans next door to Jintan, Jiangsu Province are large and weigh more than 30 grams. They are very precious big black beans. Scientific research units have also bred some high-yield and high-quality black bean varieties, such as Shandong Luhou No.2, with an yield of more than 250 kilograms per mu, which are resistant to lodging, soybean mosaic virus and cyst nematode disease. Zhangjiakou black bean is a special variety with high isoflavone content, which can be used as an excellent raw material for extracting isoflavones. As we all know, Beijing black bean is an excellent antigen against cyst nematode.