Composite nanoparticle-filled oxidized hydroxypropyl starch/carrageenan films: Robust, water-resistant, antibacterial, antioxidant and biodegradable properties

In the present study, the structure of potato oxidized hydroxypropyl starch (OHS) was analyzed. Carrageenan (CA) was used as a reinforcing agent for the development of biodegradable food packaging materials. Broccoli leaf polyphenol/soybean protein isolate/hydroxypropyl methylcellulose composite nanoparticles (SPH NPs) were used to reinforce OHS/CA (OC) films, and their physicochemical, structural, antioxidant, antimicrobial, and biodegradable properties were characterized. The OHS had high transparency, low gelatinization temperature (GT), and easy film formation. Intermolecular hydrogen bonds were formed between the SPH NPs and the OC film matrix, but did not change the crystal structure of the matrix. Furthermore, the incorporation of SPH NPs improved the smoothness, densification, and thermal stability of the OC films. Since SPH NPs occupied the pores of the film matrix, the degree of swelling, light, and moisture-blocking properties were improved, causing the films to gradually turn red, yellow and dark. Notably, the tensile strength of the film was significantly increased from 11.06 MPa to 13.61 MPa at a concentration of 3% SPH NPs. The SPH NP3-loaded films showed scavenging activity up to 67.62% and 75.45% against DPPH and ABTS free radicals, with good inhibitory activity against S. aureus and E. coli. More importantly, the composite film was almost completely degraded after 45 d of burial in the soil, and it can regulate the soil microbial community. Consequently, OHS composites can be used as a potentially versatile and environmentally friendly film-forming material for food packaging.