Kinetics of chlorophyll degradation and color loss in heated kiwifruit puree

In order to investigate thermal degradation kinetics of chlorophyll and green color of kiwifruit puree during heat processing, the effects of pH value on the chlorophyll degradation and visual green color loss in kiwifruit puree were studied at 70,80 and 90℃ combined with pH value of 3.3, 6.0 and 8.0. Results showed that the breakdown of chlorophyll a, chlorophyll b and green color loss (-a*) values followed a first-order reaction. With the increase of temperature and pH value, the rate constant and half-life value of chlorophyll a, chlorophyll b and green color loss (-a*) values decreased. The activation energies ranged from 14.69-66.02 KJ/mol, 40.88-54.64 kJ/mol and 48.55-64.14 kJ/mol for chlorophyll a, chlorophyll b and green color loss (-a*) values, respectively. In addition, significant correlation between chlorophylls and green color loss (-a*) values were found for kiwifruit puree at pH 3.3. Higher pH value would benefit for preserving chlorophylls and green color in heated kiwifruit puree.