Kinetics of Color Change of Grape Juice Generated using Linearly Increasing Temperature

Kinetics of the color change of grape juice was studied using linearly increasing temperature for heating Noble grape juice in a stainless steel reactor. The juice was heated from 60^o to 95^oC in 9 hr. Kinetic parameters for the color change were determined using Hunter L, a, b‐values, chroma values, and Total Color Difference (TCD) values. The reaction of the color change of grape juice measured by L‐ and a‐values, and Chroma value followed first order kinetics with activation energies of 114.75, 131.80, and 121.21 kJ/mol and frequency factors of 1.30 × 10¹², 8.95 × 10¹⁴ and 1.93 × 10¹³ sec⁻¹, respectively. However, the reaction measured by TCD followed zero order kinetics with the activation energy and the frequency factor of 92.81 kJ/mol and 4.80 × 10¹⁰ mol/l/sec, respectively.