Freeze-thaw cycle enhances the mechanical properties of fish gelatin/corn starch film by increasing hydrogen bonding

Abstract

The poor mechanical properties of bio-based films are the main drawbacks that limit their application. To solve this problem, the fish gelatin (FG) mixed with corn starch (CS) were prepared by melt extrusion, and pure FG films as control to study the effects of freeze-thaw cycles. The post-treatment boosted tensile strength from 11.89 to 17.77 MPa of FG/CS, improved thermal stability and optimized water vapor barrier. The addition of 20 % (w/w) CS reduced swelling rate to 262 %, and all films degraded in 3 days. In the chemical characterization, fourier transform infrared spectroscopy and protein solubility tests confirmed new hydrogen bonds between FG molecular chains and molten starch. X-ray diffraction showed the treated FG/CS film had the highest diffraction peak at 15–25° (2θ) and strongest crystallinity. In summary, the innovative use of freeze-thaw cycles as a modification method provides a high performance alternative to petroleum-based plastics while reducing costs.