Potential use of natural pigments on laccase-based TTI Prototype: Substrate specificities and variations in Arrhenius activation energy

Abstract

Non-toxic dyes and natural pigments were examined as potential substrates for a laccase-based time temperature integrator (TTI) prototype. Five compounds such as bromothymol blue (D1), methyl orange (D2), laccaic acid (P1), a pigment from bokbunja (Rubus coreanus) fruit (P2), and Gardenia blue pigment (P3) were all catalyzed, resulting in significant changes in color. CIE-Lab and ΔE appeared to have the most linear dependency on reaction time. Reaction rate constants, k, were estimated at 10–37°C with the coefficients of determination, R2, being the lowest at 0.94. The Arrhenius activation energies, Ea, were 42.6 66.1 kJ/mol depending on the substrate. The results show that alterations in Ea of this TTI is a very important finding in that Ea of the laccase-based TTI could be modulated with substrates to assess time-temperature history accurately and that a wide range of color compounds offer an opportunity for color-coded TTI to assure color blind individuals food safety.