Fabrication of Carboxymethyl Cellulose/Agar-Based Functional Films Hybridized with Alizarin and Grapefruit Seed Extract.

Carboxymethyl cellulose/agar-based functional halochromic films were fabricated by adding alizarin and grapefruit seed extract (GSE). The fillers were evenly dispersed in the polymer matrix to form compatible composite films. The addition of alizarin has improved the film's mechanical strength (20%) and water resistance (40%) with potent antioxidant and excellent color indicating properties. In contrast, GSE has imparted strong antibacterial and antioxidant activities to the film. Also, the addition of alizarin and GSE slightly improved the water vapor barrier properties but did not affect the thermal stability of the film. The composite film also exhibited UV blocking properties with adequate transparency. The composite film showed an excellent pH-dependent color change with color reversibility and color stability and a volatile gas detection function. The film also showed potent antimicrobial activity against foodborne pathogenic bacteria, Escherichia coli and Listeria monocytogenes, and showed an intense antioxidant action.