A green strategy for maintaining intelligent response and improving antioxidant properties of κ-carrageenan-based film via cork bark extractive addition

A multifunctional intelligent film was acquired by casting and drying a mixed solution of kappa-carrageenan and hydroxypropyl methylcellulose (HPMC) with Prunus maackii pomace extract (EPM) as the natural pH indicator and cork bark extract (CBE) as the antibacterial agent. The film morphology and structure were evaluated by scanning electron microscopy. With the increasing CBE content from 0% to 1.2%, tensile strength of the films decreased from 10.67 to 9.37 MPa and elongation at break increased from 43.86% to 63.89%. The barrier performance and thermal stability of the films after CBE addition still met the food packaging standards. When more than 0.4% (w/w) CBE was added, the films could effectively shield ultraviolet rays. Besides, CBE addition to the films endowed excellent antioxidant properties and resistance to food-borne pathogens, ensured pH sensitivity, and extended the service life of the intelligent film. The films maintained good responsiveness in monitoring pork freshness, and the chromaticity difference was more obvious. Thus, the present study developed a multi-functional smart film with antioxidant, antibacterial, and pH-indicating functions.

Automated summary

A multifunctional intelligent film was developed by casting and drying a mixed solution including Carrageenan, HPMC, Prunus maackii pomace extract as a pH indicator, and cork bark extract as an antibacterial agent. The addition of cork bark extract improved the film's antioxidant, antibacterial, and pH indicating properties, meeting food packaging standards in terms of barrier performance, thermal stability, and UV protection.