To make corn starch, a by-product of corn starch, the corn kernels must be soaked in sulfurous acid first. The soaking liquid is concentrated to make a yellow-brown liquid, which is called corn syrup. Corn syrup is rich in solubility. Protein, auxin and some precursor substances, containing about 40 to 50% solid matter. If lactic acid bacteria and yeast grow during the corn soaking process, the quality of the corn steep liquor will be improved; if putrefactive bacteria grow, the quality of the corn steep liquor will be reduced. Corn pulp is a commonly used organic nitrogen source for microbial growth. It can also promote the biosynthesis of antibiotics such as penicillin

Corn steep liquor dry powder is widely used in the antibiotic industry (penicillin, erythromycin , gentamicin, spectinomycin, chlortetracycline, etc.) vitamins (vc, vb2, etc.), amino acids (monosodium glutamate, lysine, phenylalanine, etc.), enzyme preparations (amylase, glucoamylase, etc.), etc. Industry, used as water-soluble, heat-conducting oil furnace in biological fermentation process.