Development and characterization of antioxidant active packaging and intelligent Al3+-sensing films based on carboxymethyl chitosan and quercetin

Different amounts of quercetin were mixed with carboxymethyl chitosan (CMCS) to develop novel antioxidant active packaging and intelligent Al³⁺-sensing films. The physical properties, structure, antioxidant and Al³⁺-sensing abilities of CMCS-quercetin composite films were investigated. Results showed CMCS-quercetin composite films presented a dark yellowish color. When compared with CMCS film, CMCS-quercetin composite films containing 5 and 7.5 wt% of quercetin on CMCS basis exhibited higher thicknesses, opacity and thermal stability; however, presented lower moisture contents, UV-vis light transmittance and elongation at break. Besides, the incorporation of quercetin could not significantly change the water solubility and water vapor barrier property of CMCS film. Morphological observation showed the surface of CMCS-quercetin composite film became coarse when 7.5 wt% of quercetin was incorporated. Infrared spectra and X-ray diffraction patterns of CMCS-quercetin composite films further indicated quercetin was compatible with CMCS. Importantly, CMCS-quercetin composite films could sustainably release antioxidant ability into aqueous and fatty food stimulants. Moreover, CMCS-quercetin composite films were sensitive to Al³⁺. The color and UV-vis absorption patterns of CMCS-quercetin composite films were changed by the addition of Al³⁺. Results suggested that CMCS-quercetin composite films could be used as novel antioxidant and intelligent Al³⁺-sensing materials in food packaging.