Process Optimization and Performance Analysis of Modified Zein Film by High Pressure Heat-Moisture (HPHM) Treatment

In this study, zein films were modified by high pressure heat-moisture (HPHM) method and the technology of HPHM modification was optimized through single experiments and L₉(3⁴) orthogonal tests, and the properties of zein film were studied. The optimal technology was as follows: Film-formation solution volume of 9 mL, treatment temperature of 112 ℃ and treatment time of 40 min. Under the optimal technology, the water absorption rate (WAR) and transparency of modified zein film was 11.35%±0.74% and 181.30±3.29, respectively, greatly improved than raw film (P<0.05). Meanwhile, the HPHM zein film exhibited obvious improved in vitro enzymatic hydrolysis resistance (14.92%±0.58%) and tensile strength (16.51±2.13 MPa). FTIR results also showed that the β-bend of zein molecule was converted to more ordered-arranged random coli, β-sheet and α-helix after HPHM modification. This study could provide essential foundations for manufacturing high-hydrophobic protein-based films assisted by HPHM modification.