Thermal degradation kinetics of curcumin in dry-heated turmeric powder studied by front-face synchronous fluorescence spectroscopy.

By monitoring curcumin mass loss in turmeric powder subjected to dry heating at different temperatures through high performance liquid chromatography, its thermal degradation was verified to follow first-order kinetics and an Arrhenius equation linking the rate constant to temperature was established. The turmeric matrix and additional ferulic acid were demonstrated to modulate curcumin thermal degradation. To facilitate the rapid and non-destructive determination of curcumin degradation kinetics, the front-face synchronous fluorescence spectroscopy (FFSFS) data of the heated samples were correlated with curcumin content via partial least squares regression (PLSR). The resultant model accurately predicted the residual curcumin after heating, with an external validation determination coefficient > 0.9, a root mean square error of prediction <0.07 mg and a residual prediction deviation >4. Additionally, a supplementary model was derived to estimate the processing time at each temperature. FFSFS coupled with PLSR provides a novel approach for in-process curcumin degradation monitoring.