Biosurfactants produced from corn steep liquor and other nonconventional sources: Their application in different industries

Corn steep liquor (CSL) is a liquid by-product generated in the corn wet-milling industry. This fermented stream is obtained when corn is digested with warm water and SO2 in the presence of different spontaneously growing microorganisms. The microbial population of CSL includes Lactobacillus and Bacillus strains, which are widely known to produce biosurfactants. These biosurfactants are obtained by liquid-liquid extraction using organic solvents. Generally, the biosurfactant extract obtained from CSL is composed of free fatty acids, lipopeptides, and phospholipids. Therefore, based on its composition, this biosurfactant extract can be considered a multifunctional ingredient with interesting properties for different industries such as environmental remediation, nanotechnology, food, agrochemical, cosmetic, pharmaceutical, and personal care. Among these, the more interesting applications are in the cosmetic and personal care industries as (i) cleaning and softer agents for virgin or dyed hair, (ii) sunscreen agents, (iii) stabilizing agents of Pickering emulsions containing nonsoluble active principles including Zn pyrithione, (iv) protective agents for unstable compounds like vitamin C, (v) preservative agents against bacteria, and (vi) active ingredients in antiacne formulations.