Colorimetric pH-sensitive hydrogel film based on kappa-carrageenan containing quercetin or eucalyptus leaf extract for freshness monitoring of chicken meat

In this study, we created new pH-sensitive hydrogel films using κ-carrageenan (CG) and either quercetin (QUE) or eucalyptus leaf extract (ELE) to monitor the spoilage of chicken meat. The ability to monitor and control freshness was confirmed by observing the dependence of color on pH changes and measuring total volatile basic nitrogen (TVB-N) levels for CG-QUE (26.5) and CG-ELE (29.75). After conducting a UV-Vis analysis, it was established that films containing 0.3 % of QUE or ELE, with transparency levels above 90 %, have the potential for further research. We found that CG-ELE was more effective in preventing bacterial growth and reducing spoilage compared to CG-QUE. The CG-ELE film also had superior mechanical behavior with higher tensile strength (13.2 ± 0.6 MPa) and lower elongation at break of (5 ± 0.1). Our findings confirmed the preference and superiority of ELE over QUE based on colorimetric response and antibacterial properties.