Development of chitosan-based biodegradable films enriched with thyme essential oil and additives for potential applications in packaging of fresh collard greens.

In the present study, chitosan (CH) based biodegradable films were developed enriched with thyme essential oil (TEO) incorporated with different additives including zinc oxide (ZnO), polyethylene glycol (PEG), nano clay (NC), and calcium chloride (CaCl2) and characterize the postharvest quality of 'collard greens' during refrigerated storage. The results indicated that the incorporation of ZnO/PEG/NC/CaCl2 in CH-based films significantly decreased water vapor transmission rate, increased tensile strength, and were water soluble and biodegradable in nature. Moreover, CH-TEO based films incorporated with ZnO/PEG/NC/CaCl2 were significantly effective in reducing physiological weight loss, retained total soluble solids, titratable acidity, and preserved chlorophyll contents as well as showed lesser a* values, suppressed microbial growth, and preserving appearance/sensory quality of collard greens for 24 days than LDPE and other biodegradable films. Our results suggest that CH-based films enriched with TEO and additives such as ZnO/CaCl2/NC/PEG are an ecological, environmental friendly, and effective alternative approach to retain shelf life of collard greens during refrigerated storage.