Colorimetric sensors based on hibiscus anthocyanins produced by continuous solution casting

Anthocyanins from dried hibiscus petals were efficiently extracted by an ultrasound-assisted technique and incorporated to cornstarch/beeswax films to be used as colorimetric sensors for meat spoilage. The sensors were produced by a pilot-scale continuous solution casting technique. The incorporation of beeswax and the extract reduced by 84% and 85% the tensile strength and elastic modulus, respectively, increased the elongation at break by 319% and the water vapor barrier by 32%. The colorimetric properties of the films were due to the extract, main and specifically their sensory capacities. When exposed to ammonia concentrations lower than 105 mg m⁻², the films rapidly and perceptively changed their color, stabilizing that change after at least 10 min. Moreover, the films slightly changed their color when exposed to meat spoilage volatiles for 6 h or less. Therefore, the properties achieved in this study, for the films produced by the continuous solution casting technique, allow them to be used as colorimetric sensors for intelligent packaging.