Evaluation of antioxidant and intelligent films for pork packaging and spoilage monitoring based on maize starch, carrageenan gum, and Rosa chinensis flower extracts

Bio-degradable, active and intelligent films have sparked interest recently due to its great potential for food freshness monitoring. In this study, antioxidant and intelligent films were developed using carrageenan gum (CG), maize starch (MS), and anthocyanin from fresh Rosa chinensis flower extracts (RFE) and their physical, functional and structural properties were evaluated. The results indicated that incorporation of RFE with different amounts (1.2–3.6 mL/g, on MS basis) significantly increased thickness (0.063–0.092 mm), moisture content (10.16–14.12%), opacity, thermodynamic stability, elongation at break (13.75–28.68%) and decreased water contact angle ( \(96.7-30.5\,^{\circ }\) $96.7-30.5{}^{\circ }$ ) and tensile strength (45.48–16.28 MPa) of the films. The structural characterization revealed the formation of intermolecular hydrogen bonds between RFE and MS or CG in MS-CG-RFE films. The MS-CG-RFE films showed excellent pH and ammonia sensitivities with different colors from red to green. The MS-CG-RFE-C film displayed strong antioxidant activity, with a maximum DPPH radical scavenging rate of 71.72%. When employed for pork freshness monitoring, the MS-CG-RFE films showed visible color changes in response to changes of pork freshness. These findings imply that MS-CG-RFE films can be used in antioxidant and intelligent packaging in the food industry.