What is koji? Jiuqu, formerly known as Jiuzuo, is only that modern people have removed the word "rice" on the left for simplification.
The so-called distiller's yeast is to transplant the conidia of Aspergillus into the strongly cooked white rice, and then start to keep warm, so that lush hyphae will grow on the rice grains, which is distiller's yeast.
In fact, the addition of distiller's yeast is a great invention of China people's brewing. For example, foreign wine is either fermented wine or mixed wine, and China liquor, because of the addition of distiller's yeast, has become an important link different from foreign wine.
Adding koji is mainly because it contains a large number of microorganisms and molds such as protease and amylase secreted by these microorganisms. These molds have biocatalysis, which can accelerate the transformation of raw materials into starch, glucose and other substances.
Traditional soy sauce, just like farming, needs down-to-earth efforts, until the harvest time: before the start, put soybeans on flour and ferment them into a "trickle", then put the trickle into a crock, inject salt water, baptize in the sun, ferment in the long river of time, and precipitate for more than 100 days, successfully transforming delicious amino acids. You can make wine only with Qu, and you can make soy sauce only with Juan. Lieru, Shuanghuang soy sauce is a high-grade soy sauce made by twice koji-making and fermentation. It is made of soy sauce fermented by the first koji and the second koji.
It takes half a year before and after the fermentation cycle, which is a veritable "double soy sauce". Soy sauce is especially delicious because of its high concentration, strong sauce flavor and dark color.