There are two kinds of liquor production: solid fermentation and liquid fermentation. What is its production process?

Liquor is a unique distilled liquor in the world. It is a beverage made of wheat, sorghum, corn, sweet potato, rice bran and other fruits through fermentation, koji and distillation. Its liquor is colorless and transparent, so it is called liquor. Liquor is rich in aroma, mellow and soft, and has various flavors. Because it mainly uses burning (steaming) process, it is also called shochu. Because of its high alcohol content, some places call it strong liquor or high-alcohol liquor. China famous wine has a long history and is unparalleled in the world.

There are two kinds of liquor production in China: solid fermentation and liquid fermentation. Among the solid-state fermentation processes such as Daqu, Xiaoqu and bran koji, bran koji occupies a large proportion in production. Here, only the technology of bran koji wine is briefly introduced.

Production method:

Raw material crushing: The purpose of raw material crushing is to facilitate cooking and make full use of starch. According to the characteristics of raw materials, the fineness requirements of crushing are also different. More than 60% of raw materials such as dried potatoes and corn pass through a 20-hole sieve.

Ingredients: mix new materials, distiller's grains, auxiliary materials and water together to lay the foundation for saccharification and fermentation. The ingredients should be determined according to the size of retort, starch content of raw materials, temperature, production technology and fermentation time. The specific performance of appropriate ingredients depends on the starch concentration, acidity and looseness of fermented grains in the pool. Generally speaking, the starch concentration is 14 ~ 16% and the acidity is 0.6 ~ 0.8.

Cooking gelatinization: gelatinize starch by cooking. It is beneficial to the action of amylase and can kill miscellaneous bacteria. The temperature and time of cooking depend on the kind of raw materials and the degree of crushing. Ordinary materials are steamed at normal pressure for 20 ~ 30 minutes. The requirement of cooking is that the appearance is steamed thoroughly, cooked but not sticky, and there is no heart inside. Mixing raw materials with fermented grains, steamed wine and steamed materials at the same time is called "mixed steaming and mixed burning". In the early stage, steaming was the main method, and the temperature in retort was required to be 85 ~ 90℃. After steaming wine, gelatinization should be maintained for a period of time. If steaming wine and steaming materials are carried out separately, it is called "steaming".

Cooling: The cooked raw materials should be cooled quickly by slag extraction or air drying to make them reach the temperature suitable for microbial growth. If the temperature is 5 ~ 10℃, the product temperature should be reduced to 30 ~ 32℃, and if the temperature is 10 ~ 15℃, the product temperature should be reduced to 25 ~ 28℃. Slag extraction or drying can also play a role in volatilizing odor and absorbing oxygen.

Stir grain: Solid state fermentation of bran koji liquor is a two-way fermentation process of saccharification and fermentation. After slag extraction, add koji and yeast at the same time. The amount of distiller's yeast depends on its saccharifying power, which is generally 8 ~ 10% of the main brewing material, and the amount of distiller's yeast is generally 4 ~ 6% of the total feeding amount. In order to facilitate the normal enzymatic reaction, water should be added when the fermented grains are stirred, and the water content of the fermented grains should be controlled at 58 ~ 62% when entering the pool.

Fermentation in the cellar: the temperature of fermented grains when entering the cellar should be 18 ~ 20℃, and the fermented grains in the cellar should not be pressed too tightly or too loosely. Generally, it is appropriate to pack about 630 ~ 640 kg of fermented grains per cubic meter. After canning, cover the fermented grains with a layer of bran, seal them with pit mud, and add a layer of bran. The fermentation process is mainly to master the product temperature and analyze the changes of moisture, acidity, alcohol consumption and starch residue at any time.

Steamed wine: Fermented fermented grains are called fragrant grains and contain extremely complicated ingredients. The effective components such as alcohol, water, higher alcohols and acids in fermented grains are evaporated into steam by steaming wine, and then cooled to obtain liquor. During distillation, alcohol, aromatic substances and sweet substances should be extracted as much as possible, and impurities should be removed by pinching the head and tail as much as possible.