A chitosan-based edible film with clove essential oil and nisin for improving the quality and shelf life of pork patties in cold storage

This study assessed chitosan (CS)-based edible films with clove essential oil (CO) and nisin (NI) singly or in combination, for improving quality and shelf life of pork patties stored in cold conditions. The treatments were control (without chitosan film coating), CS, CS-CO, CS-NI, and CS-CO-NI, and these were tested for physicochemical, microbiological and sensory qualities for 15 days (3 days per interval) on samples in cold storage (4 ± 2 °C). Overall, the results showed that the lightness (L* value) (53.47 to 67.58), yellowness (b* value) (1.32 to 2.88), pH (5.31 to 7.98), metmyoglobin (MetMb) content (54.10 to 63.36%), free fatty acid (FFA) (0.67 to 3.17%), peroxide value (PV) (0.80 to 3.67 milliequivalent/100 g), thiobarbituric acid reactive substances (TBARS) (0.69 to 3.27 mg MDA per kg), total viable count (TVC) (2.97 to 7.63 log CFU g(−1)), psychotrophic bacteria count (psychrotrophs) (2.94 to 6.59 log CFU g(−1)), Enterobacteriaceae (2.59 to 6.57 log CFU g(−1)), lactic acid bacteria (LAB) (2.53 to 6.81 log CFU g(−1)) and sensory scores (red non-discolored part (1 to 4.70), discoloration (1 to 4.40) and off-odor (1 to 5.00)) were gradually increased during storage and whereas redness (a* value) (16.43 to 8.62) and redness index (12.54 to 3.01) were decreased. However, the quality changes were minimal in the pork patties treated with CS-CO-NI. Based on sensory and microbiological evaluations, the shelf life of treated pork patties was 6 days for control, 9 days for CS and CS-NI, and 12 days for CS-CO and CS-CO-NI.