Development of active PLA/PEG-blended film with grape seed extract for straw mushroom shelf life extension
The investigation of active biodegradable packaging was carried out in 2 parts. First, poly(lactic acid), PLA, was evaluated as a flexible packaging with poly(ethylene glycol), PEG incorporation at 5, 10, 20 and 30%wt. Moreover, the compatibility of PLA/PEG at low content of PEG 10%wt was improved by the chain extender (Joncryl ADR) at 1.0, 1.25 and 1.5 phr. These polymer blends were produced with reactive blending via twin screw extruder. Then, the blended films were made with cast film extrusion process. Films were undergone the characterization processes for the followings: chemical structures, thermal properties, rheological properties, mechanical properties and gas permeability. The addition of PEG had decreased glass transition temperature, whereas it raised the crystallization of PLA. The process ability and film strength were relatively poor at PEG 20 and 30%wt but demonstrated the high elongation at break. The process ability of PLA/PEG 10%wt was improved and elongation at break was greatly developed by the ADR addition of 1.25 phr. PLA/PEG10/ADR1.25-blended film could be used as flexible packaging with acceptable process ability and gas selectivity. Therefore, in the second part, PLA/PEG10/ADR1.25 (PPA) was developed by performing as the active packaging with the incorporation of the grape seed extract (GSE) 1, 2, 3 and 4 phr along with PLA-g-MA 3%wt. PPA with GSE 4 phr film was the only formula that had good compatibility and mechanical properties. Moreover, it exhibited excellent gas-selective film behavior which restricted oxygen gas permeation but allowed carbon dioxide gas to pass through permeation. In addition, PPA with GSE 4 phr film also revealed the effective antibacterial up to 99%. Finally, PPA with GSE 4 phr film had shown the best active packaging which could extend shelf life of straw mushrooms for at least 13 days.
Graphical abstract PLA/PEG10/ADR1.25 (PPA) with GSE 4 phr film exhibited excellent gas selective film behavior which restricted oxygen gas permeation but allowed carbon dioxide gas to pass through permeation. In addition, PPA with GSE 4 phr film also revealed the effective antibacterial up to 99%. PPA with GSE 4 phr film had shown the best active packaging which could extend shelf life of straw mushrooms for at least 13 days