RESPIRATION KINETICS OF MANGOES AND ASIAN PEAR FRUITS UNDER MA CONDITIONS AND ITS RELATION TO THE RIPENING BEHAVIOURS

Abstract

Respiration of two cultivars of mango and one of Asian pear under MA was determined indirectly by numerical analysis of time-course changes in gas concentration inside the closed package system. Under MA conditions, the CO 2 production rate was approximately constant while O 2 consumption rate depended linearly on O 2 level inside the package for both pear and mango. The kinetic constant of oxygen consumption rate (dO 2 /dt) was 1.40(O 2 ), 0.92(O 2 ), 0.25(O 2 ) while the CO 2 production rate (dCO 2 ) was 12.2, 8.87 ,4.60 ml.hr -1 .kg -1 , respectively in 'Nam Dork Mai' mango, 'Keaw Sawoey' mango and 'Pien Pu' pear. When the calculated respiration function was fitted into the mathematical model describing the net rate change of CO 2 and O 2 due to fruit respiration and gas permeation through the package film, the predicted MA conditions closely described the actual conditions inside the package. The respiration kinetics supported the result that PVC sealed packaging had less effect in delaying ripening of low-respiring 'Pien Pu' pear but caused anaerobiosis to occur in high-respiring 'Nam Dork Mai' mango. A difference in depletion of internal O 2 level in different kind of fruits under the MA condition was also observed.