Investigating the Preservative Effect of Edible Coating Based on Chitosan-Gelatin Containing Satureja bachtiarica and Nepeta binaludensis Essential Oils Nanoemulsions on the Physicochemical, Microbial and Sensory Properties of Burger During Cold Storage.

This study investigated the effectiveness of chitosan-gelatin (CG) based coatings enriched with free and nanoemulsion forms of Satureja bachtiarica (SE) and Nepeta binaludensis (NE) essential oils on the quality of beef burgers during 12-day refrigerated storage. GC-MS analysis identified 37 and 50 phytochemicals in SE and NE, respectively, with carvacrol and 1,8-cineole being prominent compounds. The nanoemulsions were characterized by a spherical shape, a size range of 65.6-122.4 nm, low, polydispersity index (0.286-0.391), zeta potential between -26.7 and -38.2 mV, and high encapsulation efficiency (83.96%-85.31%). While nano-encapsulation slightly reduced total phenol content, it enhanced the essential oils' antimicrobial activity. Over the storage period, the pH, total volatile basic nitrogen (TVB-N), and microbial load of all burger treatments increased, while L* and a* values decreased. Compared with the control, burgers coated with the SE nanoemulsion exhibited a 52.9% reduction in TVB-N (14.90 vs. 31.62 mg N/100 g) and a 38.8%, 42.7%, 39.7%, and 57.1% reduction in viable mesophilic bacteria, psychrotrophic bacteria, LAB, and coliform counts, respectively, on day 12. Moreover, the NE nanoemulsion reduced mold and yeast counts by 48.2% compared with the control (2.54 vs. 4.90 log CFU/g). The nanoemulsion forms of the essential oils demonstrated superior antimicrobial efficacy throughout storage, with the SE nanoemulsion-coated burgers exhibiting the highest activity at the end of the trial. Sensory evaluation confirmed that these active coatings maintained burger acceptability. These findings suggest that CG-based coatings enriched with SE and NE nanoemulsions are a promising solution for extending the shelf life of beef burgers.