Corn Steep Liquor as an Efficient Bioresource for Functional Components Production by Biotransformation Technology

Corn is an important crop that can be used to produce many bioactive compounds. These functional components have been widely applied in the pharmaceutical, cosmetic, and food industries. Corn steep liquor (CSL) is a by-product of deep processing of corn that contains a lot of protein, peptides, amino acids, vitamins, and other nutrients, which is considered to be a rich and cheap source of plant nutrients. However, CSL is not widely used and factories are required to treat CSL as waste water directly; therefore, the question of how to turn CSL waste into a valuable product is likely to become a hot topic. In order to fully explore the potential utilization value of CSL, this review comprehensively summarizes the structural composition and nutritional characteristics of CSL, and its application and prospect in the biotransformation of industrialized organic acids, polysaccharides, lipids, enzymes, natural pigments, and novel functional components through the microbial fermentation pathway. Furthermore, specific methods for bioconverting various active substances using CSL were proposed, and the influences of various production conditions on the yield of the bioactive substances were fully analyzed and discussed. This article provides a reference for the efficient utilization of corn steep liquor as a by-product of corn processing.