Biodegradable Chicken Feet Gelatin–Clove Oil Active Films for Environmentally Friendly Food Packaging

Chicken feet, an abundant and low-cost poultry by-product rich in collagen, were used to extract gelatin, which was then formulated into active biodegradable films containing food-grade clove essential oil (CEO), glycerol, sorbitol, and Tween 20. Gelatin extraction involved 0.5 M NaOH pretreatment followed by 5% acetic acid extraction at 66 °C, yielding 11.22% gelatin. Eight gelatin–CEO films were prepared by varying the CEO concentration and plasticizer composition. The supplier-declared CEO composition was eugenol-dominant, and antibacterial activity against Escherichia coli, Kluyvera sp., and Enterobacter cloacae was assessed by agar disk diffusion, MIC, and MBC assays, each performed in triplicate. CEO inhibition zones of 22, 14, and 19 mm were recorded against E. coli, Kluyvera sp., and E. cloacae, respectively; the blank 6 mm control disks without oil produced no inhibition halo beyond the disk edge. MIC/MBC values were 5/6, 3/4, and 4/5 mg/mL for the same three strains. All films were continuous, smooth, and peelable; sorbitol-containing formulations were clearer and more flexible than sorbitol-free variants. Water solubility ranged from 37.67% to 48.78%, opacity from 5.26 × 10−3 to 9.20 × 10−3 A500 mm−1, and thickness from 11.75 to 23.75 µm. Water vapor transfer was undetectable under the gravimetric screening protocol for all formulations. All films showed complete visual disappearance in soil within 6–10 days. In the cherry tomato trial, the best-performing coatings extended acceptable storage from about 5 days (uncoated control) to 10 days at 17–20 °C.