Ameliorating the prediction ability of laccase time temperature indicator for dynamic monitoring quality of fresh‐cut papaya

Laccase was immobilised on electrospun chitosan fibres to prepare a laccase time–temperature indicator (LTTI) to predict the quality deterioration of fresh‐cut papaya. Using sodium azide (NaN 3 ) as an enzyme inhibitor could retard the laccase‐catalysed coloration and to expand activation energy ( Ea ) range, in which the LTTI was calibrated to correlate with fresh‐cut papaya deterioration. The fresh‐cut papaya reaching total plate count (TPC) of 10 5 CFU g −1 demonstrated unacceptable quality and the time it took was close to the coloration endpoint of formulated LTTI at different storage temperatures. The Ea of the LTTI, formulated with 20 μg cm −2 of laccase and 0.1 m m NaN 3 , was 55.69 kJ mol −1 , which only differed by approximately 15 kJ mol −1 from the Ea of the TPC of fresh‐cut papaya. In the 5, 15, 25, and 35 °C isothermal response tests, the prediction errors were 1.15%, 2.78%, 2.78%, and 0.83%, respectively. In temperature fluctuation response experiments, the coloration endpoint of the LTTI was correlated with the quality deterioration of fresh‐cut papaya. These results revealed that the formulated LTTI had high reliability in evaluating the shelf life of fresh‐cut papaya.