Preparation of polyvinyl alcohol/carboxymethyl cellulose sodium/chitosan paper-based antimicrobial indicator cards using mixed anthocyanin with stability-colorimetric sensitivity: Monitoring freshness of carp

Abstract

In this study, an anthocyanin solution with both high stability and sensitivity was successfully prepared through a blending method, and the optimal ratio was determined. Ultraviolet-visible spectroscopy analysis demonstrated that an increase in the proportion of black bean peel anthocyanins resulted in a deeper color and a more pronounced color change effect. Moreover, the stability of the blended anthocyanins was markedly enhanced with an increase in the proportion of purple cabbage anthocyanins, resulting in a slower decomposition rate under light, temperature, oxidation, and varying pH conditions. The blended anthocyanins, employed as a pH indicator, were utilized to prepare an antibacterial indicator card. It was observed that the mechanical properties of the coated paper remained unaltered by the ratio of the mixed pigments. The mixed pigments enhanced the stability of the antibacterial indicator card with respect to environmental fluctuations while facilitating more rapid and sensitive color transitions in the presence of ammonia and under disparate pH conditions. The application of indicator cards with five different anthocyanin ratios to fish resulted in a shelf life extension of 1–2 days compared to the control group and enabled real-time monitoring of fish freshness. A comprehensive evaluation demonstrated that the optimal indicator performance was attained when the mass ratio of black bean peel anthocyanins to purple cabbage anthocyanins was 1:1.