Exopolysaccharides are the secreted polysaccharides from microorganisms. These complex sugars play a large role in the formation of biofilms and modulation of texture in fermented foods [35, 36]. While these polysaccharides are commonly produced by lactic acid bacteria (LAB), they can also be produced by fungi such as Aureobasidium pullulans, which has been shown to produce pullulans on deproteinized whey permeate . More recently, xanthan gum, a ubiquitous stabilizer/thickener in the food industry, has been produced from whey permeate. While the medium must first undergo lactose hydrolysis with P-galactosidase to release glucose and galactose for optimal polysaccharide production, this study illustrates an outlet for adding value to whey permeate .
Beyond modifying texture of food products, whey permeate can be transformed into products which modify the rheological properties of cosmetics or act as common household or industrial detergents. Biosurfactants are recognized for their biodegradability and low environmental impact, and have gained popularity over the past several decades. Beyond their cosmetic or typical cleaning applications, they have also been suggested as a remediation tool due to their ability to facilitate adsorption by microorganisms which degrade the hydrocarbons . One of the most common types of biosurfactants is glycolipids, which have a hydrophilic sugar-containing head group and a hydrophobic tail. In order to biosynthesize these surfactants, the fermentation broth must contain a sugar source as well as a fatty acid source, in the form of a free fatty acid, fatty acid methyl or ethyl ester, or even a triglyceride. A popular example of a biosurfactant is the sophorolipid, which is produced in great quantities (over 400 g/L) by the fungus Candida bombicola . It has been produced by combining whey permeate with glucose and oleic acid, which are collectively metabolized into sophorolipids . Due to its cheap and plentiful source of sugars, whey permeate could be an attractive feedstock for biosurfactant production.