Changes in color parameters of corn kernels during roasting

Changes in color parameters (L*, a*, b*, ΔE*, h°, and C* values) of corn during roasting were investigated and subsequently described using mathematical models. Corn kernels were roasted for 50 min at 160, 180, 200, 220, and 240°C. The L*, b*, h°, and C* values tended to decrease more rapidly as the roasting temperature and time increased up to 220°C and 50 min, whereas a* and ΔE* values tended to increase. Variation of L* and ΔE* values was found to be proportional to the roasting temperature and time. Variation of L* value during roasting above 180°C was adequately described by a first-order model. Cubic model satisfactorily described changes in all of color parameters over the temperature range. Activation energies of L* and ΔE* values were determined as 34.04 and 79.16 kJ/mol, respectively. Results suggest that L* and ΔE* values may be used as color control indicators during roasting of corn kernels.