Casein is the major precipitated protein of milk at the temperature of 20℃ and a pH value of 4.6. Casein is a phosphorus-containing protein, which has a high content and nutrient value. Bovine casein is made up of as1-, as2-, k-, and b-casein. These four monomers constitute the spatial structure of casein via a-helix, b-sheet, and b-turn. b-Casein from bovine can be used as a superior emulsifier and colloid stabilizer. The pH value is 4.8, which is the isoelectric point of casein. Casein has excellent steric stability to dispersed oil/fat droplets under neutral pH.
A solution containing only casein could not be electrospun due to its strong intermolecular force and 3D structure. However composite dispersions blending PEO or PVA with casein could be electrospun successfully as indicated in Figure. The 10% (w/w) casein solutions containing 80% PEO or 50% PVA are used to electrospin with average fiber diameters ranging from 100 to 500 nm.