Effect of pH on chlorophyll degradation and colour loss in blanched green peas

Abstract: Effect of pH on the chlorophyll degradation and visual green colour loss in blanched green peas were studied at 70, 80, 90 and 100°C in buffered solutions of pH 5.5, 6.5 and 7.5. The degradation of chlorophylls a and b followed a first-order reaction and the temperature-dependence of these reactions was modelled by the Arrhenius equation. The activation energies ranged from 4.80±0.91 to 14.0±0.71kcalmol−1 for chlorophyll a and from 6.84±0.29 to 11.0±1.06 for chlorophyll b with varying pH values. The visual green colour degradation, as represented by the change of the −a (greenness), the ratio −a/b and hue (h) values measured by tristimulus colorimeter, also followed a first-order reaction. Activation energies for −a values ranged from 8.13±0.71 to 12.0±1.07kcalmol−1, and for −a/b values ranged from 8.77±1.34 to 12.0±1.07kcalmol−1 with varying pH values at 70, 80, 90 and 100°C. [Copyright &y& Elsevier]