Antioxidant and Antibacterial Properties of Essential Oils from Citrus reticulata cv. Shatangju Peel for the Preservation of Chilled Pork

Citrus reticulata cv. Shatangju peel essential oil (CrspEo), with three major components D-limonene (88.15%), γ-terpinene (4.59%) and β-myrcene (2.62%), possessed antioxidant activities with DPPH and ABTS⁺ radical scavenging with the IC₅₀ (concentration of CrspEo scavenging 50% of radical) of 9.87±0.12% and 0.48±0.02%, respectively. Meanwhile, CrspEo showed antimicrobial activity in suppressing the growth of Bacillus pumilus, Bacillus subtilis, Candida albicans, Escherichia coli, Staphylococcus aureus, and Saccharomyces cerevisiae with Minimum Inhibitory Concentration (MIC) in the range of 0.04-0.32%. To investigate the preservation performance of CrspEo in chilled pork stored at 4°C, the CrspEo, in the concentrations of 0, 0.5, and 1% (v/v) [denoted as BC, LC, and HC, respectively], were used to treat the chilled pork, which was controlled with 5 mg/mL sodium benzoate solution (PC). The CrspEo treatments showed lower pH, thiobarbituric acid reactive substances, percentage of metmyoglobin, total volatile basic nitrogen, and the total viable count and higher protein solubility than the BC treatment during storage and were consistent with those obtained by the PC treatment. Yersinia ruckeri and Enterobacter agglomerans were identified in the chilled pork. Both of the two bacteria were sensitive to the CrspEo and the E. agglomerans is dominant in the spoilage of the pork samples. The sensory properties of chilled pork treated with CrspEo were not affected and the shelf-life of chilled pork can be extended by CrspEo from 6 days to 9 days. Hence, CrspEo could effectively retard the spoilage of chilled pork.