Catechol browning -defined as the formation of coloured and spectrally active species -was assessed, in triplicate (i.e. n = 3), using spectrophotometric methods. Initial browning reactions were conducted in DMEM; catechol concentrations ranged from 0.2 to 15.6 mM. All components were pre-warmed to 37 °C, and reactions were initiated by adding 20 L of serial dilutions of catechol to 180 L of DMEM in a transparent 96-well microplate, resulting in a final well volume of 200 L. Browning was monitored using a Molecular Devices Spectramax 250 microplate reader, with absorbance at 340 nm recorded every 10 min over a 190-min period; reactions were maintained at 37 °C, with microplate shaking before each reading. Browning rates were calculated as the change in absorbance at 340 nm over time.