Effects of nanoemulsion-based edible coatings with composite mixture of rosemary extract and ε-poly-l-lysine on the shelf life of ready-to-eat carbonado chicken

Spoilage of ready-to-eat carbonado chicken during storage usually causes safety concerns and economic losses. A novel edible nanoemulsion coating with natural antimicrobial and antioxidant was applied to improve carbonado chicken shelf life. The nanoemulsion based on gelatin and chitosan incorporated a mixture of rosemary extract and ε-poly-l-lysine (ε-PL) and was fabricated by high pressure homogenization. Emulsion droplet size and ζ-potential were examined by a zetasizer, and the mean droplet sizes were 257 nm and 1122.44 nm for the nanoemulsion and a coarse emulsion, respectively. A higher ζ-potential was obtained for the nanoemulsion (+32.50 mV) than for the coarse emulsion (+26.25 mV). The rheological properties of the coating solutions showed shear-thinning behavior. Microstructure analysis of the coating showed that the nanoemulsion possessed smoother and more homogeneous surfaces without pores and with better structural integrity than those of the coarse emulsion. Ready-to-eat carbonado chicken coated with the gelatin-chitosan solution, coarse emulsion, or nanoemulsion and uncoated samples were prepared for a preservation study. Samples coated by the nanoemulsion displayed the lowest total viable bacterial counts (TVC), mold and yeast counts, TBARS values, and pH changes under 4 °C refrigeration over 16 days. The nanoemulsion-coated carbonado chicken shelf life was prolonged by at least 6 days compared to that of the control. The nanoemulsion-based edible coating, as a novel antimicrobial and antioxidant material, effectively sustained active compound release to the meat surface and is a promising technology to improve the safety and quality of ready-to-eat meat products.