Development of an Active Almond Gum/Gelatin Bio-Composite Film With Rosemary Essential Oil for Extending the Shelf...

This study investigated the development and optimization of a bioactive edible film based on almond gum-gelatin matrix incorporated with rosemary essential oil (REO) and plasticized with glycerol, using a Box-Behnken design (BBD). The optimization process proved high reliability with adjusted coefficients of determination (R² _adj) ranging consistently between 0.986 and 0.999 across all studied responses. The optimized formulation (5% almond gum, 2% REO, and 24.8% glycerol) achieved a tensile strength of 29.23 MPa and an antioxidant activity (2,2-diphenyl-1-picrylhydrazyl [DPPH]) of 79.012%. FTIR analysis of the optimized film showed a successful cross-linking and intermolecular hydrogen bonding between biopolymers and REO, while DSC thermograms proved enhanced thermal stability of the composite matrix. Characterization revealed low opacity and high antimicrobial activity with > 16 mm of inhibition zones against Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus, by the agar disk diffusion method. Applied on refrigerated chicken fillets for 12 days, the active film significantly suppressed microbial proliferation (TAB, Pseudomonas spp, and psychrotrophic bacteria) compared to control samples. It also significantly retarded chemical alteration, maintaining total volatile basic nitrogen (TVB-N: 25.12 mg/100 g) and thiobarbituric acid reactive substances (TBARS: 0.38 mg malondialdehyde [MDA]/kg) within acceptable limits. These results confirm that the optimized active edible film can be an important transition as an active protection system, delaying microbial proliferation, sensory shelf life, and lipid oxidation of refrigerated poultry meat from 6 days (control) to 12 days.