Kinetic assays confirmed that catechol browning -as observed through spectral scans -is influenced by its concentration, pH, and temperature. In the absence of amines, the baseline browning rate was dependent on catechol concentration and was notably sensitive to pH between 7.0-8.0 (Fig. ). At low catechol concentrations (0.1-0.5 mM), browning rates were slower and more variable, and the linearity of the rate-pH relationship was poorer (e.g. r² = 0.7567 for 0.1 mM catechol at pH 7.0-8.0; n = 3 independent kinetic assays); at higher catechol concentrations (≥ 1.0 mM), browning rates were faster, more consistent, and showed stronger linearity (e.g. r² = 0.9948 for 15.6 mM catechol, n = 3). Temperature also significantly affected browning: rates at 25 °C were ~33% of those at 37 °C, and no browning was detected at 4 °C during the 6-h incubation (Figs. ).