2. Steaming: firstly, all kinds of solid raw materials are crushed, soaked in water for 24 hours, and then steamed in a large pot with appropriate amount of water until cooked, so that the contact surface between raw materials and microorganisms can be expanded. It is beneficial to gelatinization uniformity, and it also has the effect of accelerating saccharification after starch is steamed.
3. koji mixing: stew the steamed raw materials for 10-20 minutes, spread them out, cool down to below 40°C, mix in Daqu, yeast solution and acetic acid solution, stir for 2-3 times to make them uniform, and cool down to17-/kloc fashion cylinder, which has low temperature tolerance.
4. Fermentation: After the raw materials are mixed with koji and put into a jar, they begin to enter the stage of saccharification and alcohol fermentation. At this time, the appropriate temperature is 25-30 C. After one week, the material temperature drops, the alcohol oxidation is over, and the acetylation is completed.
5. After vinegar in the aging tank, adding water to reduce the alcohol concentration in the vinegar solution is beneficial to the propagation and growth of acetic acid bacteria in the air for natural brewing. Generally, 300-350kg of water is added to every100kg of material, which takes about 20-30 days in summer and 40-50 days in winter and spring. When the vinegar liquid becomes sour, there is a thin film of acetic acid bacteria on the vinegar surface, which gives off a pungent sour taste. The upper liquid is clear, and the middle and lower liquid is raw material color and slightly turbid. Mixing the two, filtering to remove solid suspended matter, and sealing and packaging to obtain commercial aged vinegar.