Properties and potential medical applications of regenerated casein fibers crosslinked with citric acid

Regenerated protein fibers developed from casein using alkaline solutions and crosslinked with citric acid have good tensile properties and water stability but were cytotoxic. Casein is obtained as a byproduct during skim milk production but has limited industrial applications. In this research, casein was dissolved using alkaline solutions and the effects of fiber formation conditions on the tensile properties was studied before and after crosslinking with citric acid. Crosslinked casein fibers had tensile strength as high as 110 MPa and breaking elongation of 13.6%. The fibers were also stable in 90 °C water between pH 3 and 9 but were hydrolyzed at pH 11. Casein was cytotoxic and did not support the attachment and growth of mouse fibroblasts.