Immobilizing laccase on electrospun chitosan fiber to prepare time-temperature indicator for food quality monitoring

Abstract

Laccase was immobilized on the electrospun chitosan/poly(vinyl alcohol) fiber (ceCPL) with specific area of 17.05 m2/g to reinforce the stability of enzymatic time–temperature indicator (TTI). The ceCPL exhibited a high relative activity within 4 °C–40 °C and the activation energy (Ea) of coloration with guaiacol approached 40.9 ± 2.8 kJ/mol for 80 μg/cm2 of ceCPL-immobilized laccase. In dynamic temperature response experiments of ceCPL using intermittent temperature changes between 4 °C and 25 °C, irreversible inactivation did not occur, indicating the desirable tolerance and sensitivity of ceCPL to temperature alterations. Approximately 1 or 38 days was required to reach the endpoint of coloration at 4 °C when 80 or 8 μg/cm2 of laccase were immobilized on ceCPL, respectively. The regression equation derived from kinetic model analysis was conducted and could be further utilized to design a suitable time–temperature indicator (TTI) to monitor food quality according to the color change of ceCPL coloration.