Thermal degradation kinetics study of curcumin with nonlinear methods

Area of Science:

• Food Science
• Chemical Kinetics
• Materials Science

Background:

• Curcumin is a widely used natural food coloring agent.
• Understanding its thermal stability is crucial for food processing.
• Previous studies have not fully elucidated the decomposition kinetics and mechanisms.

Purpose of the Study:

• To determine the thermal decomposition behavior of curcumin.
• To identify the kinetic parameters and reaction mechanisms of curcumin decomposition.
• To establish safe processing temperature limits for curcumin in food applications.

Main Methods:

• Thermogravimetric analysis (TG) and Derivative Thermogravimetric analysis (DTG).
• Advanced isoconversional methods for activation energy (Eα) determination.
• Comparative and nonlinear model-fitting methods for mechanism estimation.

Main Results:

• Curcumin decomposition occurs in two stages, with the first stage limited to 190°C.
• Both decomposition stages were identified as single-step processes.
• Stage I followed random nucleation and growth; Stage II followed one-dimensional diffusion.

Conclusions:

• The processing temperature for curcumin as a food colorant should not exceed 190°C.
• The reaction mechanisms for both decomposition stages were successfully identified.
• Kinetic parameters and thermodynamic functions of transition state complexes were calculated.