Kinetics for photo-degradation of chlorophyll in postharvest fruit and vegetable

The chlorophyll showed unstability to light irradiation in processing and storage, it was determined by UV spectrophotometer and CIE-L*a*b* and HPLC, and the kinetic models of chlorophyll photo-degradation with different monochromatic lights and light intensity were studied. The results indicated that chlorophyll photo-oxidation followed a first-order model. The chlorophyll was broken down seriously during ultraviolet radiation as well as blue and red light through visible spectrum, but was influenced slightly by infrared rays. The degradation speed was inconsistent among different light intensity and the half life of chlorophyll under 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000 lux was 16.9, 14.1, 11.5, 9.8, 8.8, 8.2, 7.1, 6.0, 5.2, 4.0 h, respectively. The speed of chlorophyll a degradation was almost three or four times faster than that of chlorophyll b under the same conditions. Chlorophyll degradation wasn’t evident under 60℃ and concentration of oxygen affected photo-degradation seriously. The conclusion supplied useful reference on choosing fruits and vegetables wrapping materials and facilitating sense quality on green fruits and vegetables.