Sweet starter is mainly used to make sweet starter. In the process of making liqueur koji, liqueur koji is the main fermentation preparation. Sweet koji is saccharifying bacteria and yeast preparation, which mainly contains Rhizopus, Mucor and a small amount of yeast.

In the fermentation process, saccharifying bacteria first decompose starch in glutinous rice into glucose and protein into amino acids, and then a small amount of yeast converts glucose into alcohol through glycolytic pathway. In this way, a sweet, delicious and nutritious liqueur was made.

Rhizopus is the most important functional substance in sweet wine koji. Common Rhizopus are rhizopus nigricans (commonly known as bread mold) and Rhizopus oryzae. The optimum temperature of rhizopus nigricans is 30℃ to 35℃, and it can't grow at 37℃ (it is also said that the optimum growth temperature of rhizopus nigricans is around 28℃, and it won't grow beyond 32℃); The development temperature of Rhizopus oryzae is 30 ~ 35℃, the optimum temperature is 37℃, and it cannot grow at 465438 0℃.