Preparation of gellan gum-based layer-by-layer assembled indicator films with flame retardant, hydrophobic, and antimicrobial properties for freshness monitoring of chicken breast meat.

Abstract

Food packaging materials with flame retardant properties play a vital role in reducing the loss and spoilage of greasy food in a fire. In this study, a flame-retardant, antimicrobial, and hydrophobic double-layer indicator film was fabricated. The inner layer comprised a gellan gum (GG) matrix incorporating grape skin anthocyanin, beetroot red pigment, and shikonin, while the outer layer consisted of phytic acid (PA), Centella asiatica extract (CAE), polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), and gelatin (GL). A hydrophobic silicon dioxide (SiO2) coating was applied to the outer layer to enhance surface properties. SEM, FT-IR and XRD analyses revealed that intermolecular hydrogen bonding was the main interaction within the PA-polymer matrix. PA improved SiO2 dispersion and enhanced the optical and mechanical properties of the films. These films demonstrated a bilayer structure characterized by internal hydrophilicity and external hydrophobicity. The films with PA exhibited significant antioxidant activity (DPPH radical scavenging rate > 35 %) and antimicrobial efficacy. Compared with double-layer films without hydrophobic coating and PA, films with 10 % PA demonstrated a 199 s ignition delay with enhanced flame retardancy. In addition, the films showed a good indication and prolonged the preservation time of chicken breasts in chicken breast preservation applications. Therefore, this study broadens the application of both freshness monitoring and flame-retardant hydrophobic food packaging films for animal-derived food products.