How to ferment black beans into douchi

How do black beans ferment into fermented soybeans?

Process flow: black beans, soaking, cooking, cooling, inoculation, koji-making, salt water mixing, fermentation and drying (i.e. drying)-finished product.

1. Soaking: The purpose of soaking is to make the raw materials absorb certain moisture. When cooking, protein quickly reached moderate denaturation, and starch was easily gelatinized. The water content reached by soaking is closely related to koji making. Weigh black beans, wash them and put them in a pot. It is advisable to submerge beans with water once and a half. The water temperature is about 40 degrees, and it takes about two to five hours to soak (normal temperature is also acceptable). You can change the water once in the middle, so that the beans are soaked to more than 90% without wrinkling, and the moisture content of raw materials is 45%. However, the time required to reach the optimum water content at different soaking temperatures is different, and the production can be controlled according to different climatic conditions.

2. Cooking: The traditional craft is to cook in water for about three to four hours. Steamed beans have bean flavor, so it is best to press them thin with your fingers and crush them easily. The moisture content is about 45%. Too low water content is not conducive to the growth and reproduction of microorganisms and the production of enzymes, and the prepared products are hard but not brittle. The water content is too high, the temperature is difficult to control, miscellaneous bacteria are easy to breed, and beans are easy to rot.

Third, koji making: traditional douchi is not inoculated, but naturally inoculated at room temperature. Appropriate temperature and climate are used to promote the growth and reproduction of naturally occurring microorganisms that are beneficial to brewing, produce complex enzyme systems, and produce rich metabolites in the brewing process, which makes Douchi delicious and unique in flavor. What we do is pure music-making. Cook black beans out of the pot, cool to about 40 degrees, add the koji essence you bought, and put it evenly on the mat or bamboo weaving. The thickness is about 3-5 cm, the middle is thin and the edge is thick. Keep the product temperature at about 30-37 degrees. After 23 hours, white hyphae can be seen covered with beans. When the product temperature rises above 35 degrees, the starter will be blocked. This is the first time you can turn it. Turning is rubbing beans, which is beneficial to the formation of conidia. After 72 hours, it will be covered with hyphae, yellow and green.

4. Fermented grains fermentation, that is, after removing distiller's yeast, the spores on the surface of fermented soybean are removed (also washed off with water), and salt fermentation is mixed with brine fermentation (it can be fermented without adding salt and water). The function of fermentation and post-ripening is protease and amylase secreted by Aspergillus oryzae, among which anaerobic fermentation is the main one. According to different fermentation methods, the post-fermentation maturity is also different. Salt-free fermentation is three days, and salt-free fermentation depends on the weather and temperature. Generally, natural fermentation does not need heating, and the fermentation time needs to be determined according to the temperature, which usually takes one and a half months to six months. If it is artificially heated, it takes about 45 days, and the temperature of fermented products is 40-45. After fermentation, it is dried in the sun until the water content is about 35%, which is the finished product. Just a little sun drying will do. You can also ferment without adding salt first, which can shorten the fermentation time.