RADOV started with the development of laboratory-scale production of irradiated egg proteins and peptides. Irradiation of egg proteins was conducted under different conditions using gamma sources and e-beam accelerators. After irradiation, the products' bioactivity was evaluated with a particular focus on their antibacterial- and antioxidant properties. Two different irradiation conditions resulted in the production of materials with anti-oxidant properties. Fragmentation to peptides was confirmed for one of such cases. Concerning this, around 700 samples have already been tested and the information about each irradiation (i.e. all irradiation conditions) and the following bioactivity (or lack of bioactivity) together with structural data will be collected in a database that is under construction. The procedures and protocols for bioactivity assessment, structural determination, bulk fractionation, peptide isolation, and quantification of peptides are being developed and optimized.
Simultaneously, the egg protein and peptide-containing products are being developed initially based on model proteins used for fragmentation. The first product is a hydrogel wound dressing containing egg protein/peptide with antimicrobial/antioxidant properties. Preliminary screening was conducted using the commercial hydrogel dressing. Hydrogel film's visual appearance, water solubility, and manageability were used as qualitative criteria for a preliminary screening. A mechanical characterisation by small angle oscillatory rheometry was performed on the most promising formulations. More in-depth analysis of the gelation behaviour and microstructure of the hydrogels on selected systems was also conducted. A novel hydrogel formulation that can be loaded with three different egg white proteins, lysozyme, ovotransferrin, and ovalbumin, was identified. Gelation can be induced by e-beam irradiation at the typical sterilisation dose, freeze-thawing cycles, or a combination of the two processes. The composition, mechanical properties, swelling behaviour, and microstructure of the hydrogel films are suitable for the envisaged application as wound dressings.
The second product integrated with bioactive peptide/peptide fraction is an active food packaging film grafted with antioxidant/antimicrobial egg peptides. Two types of commercial films underwent radiation grafting meant to introduce carboxyl or amine groups on the surface. UV-vis 2D fluorescence maps were generated by testing the functionalized films coupled to proteins previously labelled with fluorescent probes. Although screening has not yet been completed, data collected so far indicate that functionalized films can be successfully coated by selected hen egg proteins.
