Characterization of Job's tears (Coix lachryma-jobi L.) starch films incorporated with clove bud essential oil and their antioxidant effects on pork belly during storage

The physical properties of Job's tears starch (JTS) films incorporated with clove bud essential oil (CBEO) and their antioxidant effects on pork belly during storage were investigated in this study. The changes in thermal properties (thermogravimetric analysis), microstructure (scanning electron microscopy), and antioxidant activity (ABTS and DPPH assays) of JTS films according to various concentrations (0.25, 0.5, and 0.75%) of CBEO were also examined. With increasing concentration of CBEO, tensile strength, moisture content, and water solubility of the films decreased, whereas elongation at break, water vapor permeability, and antioxidant activity increased. The optical and thermal properties of the JTS films were not affected with the addition of CBEO. Pork belly packaged with the JTS film containing 0.5% CBEO exhibited lower degree of lipid oxidation determined by peroxide and thiobarbituric acid reactive substances value measurement than non-packaged sample during storage. Therefore, the developed JTS films containing CBEO can be effectively applied as an anti-oxidative packaging material to maintain the freshness and quality of pork belly during storage.