Structural and mechanical properties of compression-molded wheat gluten, gliadin and glutenin enriched films

摘要

Within the future bioeconomy there is a need to replace petroleum-based plastics with renewable materials derived from plant polymers, e.g., starch and proteins.The wheat gluten proteins gliadin and glutenin offer a unique and interesting combination of strength and elasticity for utilization in the bio-based material industry.In addition, wheat gluten proteins have good oxygen barrier and film forming properties with high biodegradability potential.The aim of the present study was to examine the structural properties and protein-protein interactions in compression-molded plasticized wheat gluten, gliadin and glutenin enriched films.Differences in structural and mechanical properties of plasticized wheat gluten, gliadin and glutenin enriched films were also evaluated.Size exclusion high performance liquid chromatography (SE-HPLC) and reverse phase high performance liquid chromatography (RP-HPLC) were used to study the structural and polymerization behavior of compression-molded bioplastic films.Tensile testing was used to measure the mechanical properties.Results obtained by SE-HPLC showed that the protein solubility of compression molded wheat gluten, gliadin and glutenin enriched bioplastic films (with 30％ glycerol) in SDS extraction buffer was extremely low compared to raw gluten, gliadin and glutenin-enriched proteins.The solubility of proteins remained low even after repeated sonication.The low protein solubility is due to a high degree of protein aggregation during compression-molding at high temperature (130°C) and pressure(10 MPa).The RP-HPLC results also showed that not all the proteins were extracted when using DTT and 6 M urea, indicating the presence of covalent types of bonding other than disulphide cross-linking.Varying mechanical properties of plasticized wheat gluten, gliadin and glutenin enriched films were determined in the study.