Intelligent colorimetric pH sensoring packaging films based on sugarcane wax/agar integrated with butterfly pea flower extract for optical tracking of shrimp freshness

Abstract

A novel pH colorimetric film was prepared from various sugarcane wax (SW) concentrations (1, 1.5 and 2% w/v) on agar matrix (Agr) combined with butterfly pea flower (BF) extract for monitoring the shrimp freshness. A combination of BF anthocyanins with SW as lipid (hydrophobic) showed different changes in color under acidic conditions (pH 2–6) with slight changes under alkalinity (pH 7–12), which matched the visual color changes of two different ammonia vapors (50 and 100 mmol/l). FTIR, XRD spectra, and SEM micrographs revealed that SW was effectively fixed into the Agr-BF network during the film-forming process. The different homogenized SW films enhanced the physical and mechanical properties without significant differences in elongation and water vapor permeability. Remarkably, SW films displayed complete protection against UV–vis light (0%) and valuable reduction in visible light. This study presents SW colorimetric films as promising natural derivatives for smart packaging in tracking food freshness.