Degradation of Curcumin in the Curcuminoid Mixture as a Function of Temperature

The influence of temperature on the degradation of curcumin in the curcuminoid mixture was studied using the curcuminoid mixture solution in a 50:50 (v/v) mixture of phosphate buffer/methanol pH = 8.0. The final concentration of curcumin in the curcuminoid mixture was 25 μg/mL (68 μM). The samples were incubated at 37, 50, and 60°C for at least 24 h or until no curcumin was detected. Samples of 200 μL were withdrawn at different time points, added to 800 μL of methanol, and stored at −20°C prior to analysis using RP–HPLC.