Chitosan and gelatin based antimicrobial composite coatings functionalized with natural active agents for preservation of pork meat

Abstract

Pork is rich in protein, but its high moisture content leads to microbial spoilage, and rapid post-harvest quality degradation. Natural biopolymer-based coatings have emerged as a promising solution for preserving the food. In this research, edible coatings composed of chitosan (CH), gelatin (GL), Aloe vera gel (AVG), and nanoemulsified carvacrol (CNE) were developed to extend shelf life of vacuum-packaged pork stored at 4 °C. Five coatings i.e., CH/GL, CH/GL/AVG, CH/GL/AVG/CNE-1 (1 % CNE), CH/GL/AVG/CNE-2 (2 % CNE), and CH/GL/AVG/CNE-5 (5 % CNE) were tested. The addition of A. vera gel and CNE significantly boosted the coatings' antimicrobial efficacy, reducing mesophilic and psychrotrophic bacteria, yeast, and mold counts by 3–4 log CFU/g in the CH/GL/AVG/CNE-2 and CH/GL/AVG/CNE-5 coated samples compared to the uncoated control. Moreover, the coatings effectively slowed total volatile bases-nitrogen (TVB-N) and thiobarbituric acid (TBA) formations maintaining quality of the vacuum-packed pork for up to 16 days compared to 10 days in case of the control. The CH/GL/AVG/CNE-2 coated pork also had a sensory score above 7.8 throughout the storage period, while that for the uncoated meat dropped below 5. Overall, CH/GL/AVG/CNE-2 was effective edible coating that extended the shelf life of vacuum-packaged pork by 6 days in refrigerated conditions.