Color degradation kinetics of spinach, mustard leaves, and mixed puree

The kinetics of color degradation of spinach, mustard leaves, and mixed (mustard:spinach:fenugreek = 1:0.75:0.25) puree were investigated at temperatures between 75 and 115 degreesC. Color degradation was studied in respect to both visual green color (Hunter -a value) and total color [L x (-a) x b]. Degradation of color followed I-order reaction kinetics. Temperature dependence of the degradation rate constant obeyed the Arrhenlus relationship with activation energies ranging between 19.71 and 41.64 kJ/mol. Higher activation energy value indicated greater temperature sensitivity of mustard leaves than spinach and mixed puree. Activation energies for visual green color were consistently higher than that for total color. Visual green color could therefore be used for on-line quality control of spinach, mustard leaves, and mixed puree during thermal processing.