Physiological and Textural Changes in Balsam Pear (Momordica charantia L.) Fruit during Development and Storage

Physiological and textural changes of Balsam pear (Momordica charantia L.) fruit were investigated during development and subsequent storage. The fruits were harvested at six developmental stages of A, B, C, D, E and F, with A (immature) and F (overripe). The fruit harvested at stage C (harvesting maturity) were packaged with polyethylene film (20μm in thickness) bags and stored at 1, 10, 20 and 30°C. 1) The flesh firmness decreased with fruit development and this decrease hastened during fruit ripening. In the stored fruit, the flesh firmness decreased more rapidly at higher temperature than at lower temperature. 2) The respiration rate changed little during the early stages of fruit growth and increased during fruit ripening, showing a typical phenomenon as a respiratory climacteric. The CO2 concentration in the polyethylene film bags of stored fruit increased more rapidly at higher temperatures. 3) The ethylene production was very low in all stages of the fruit development and was the lowest at the harvesting stage C. The ethylene concentration in the polyethylene film bags of stored fruit increased earlier at higher temperature and there was no increase of ethylene concentration in the package at 1 °C. 4) The water-soluble pectin content constantly increased during fruit development, the increase being maximum during the fruit ripening. The hydrochloric acid-soluble pectin content continued to decrease during fruit development. The higher temperature in the fruit storage made the water-soluble pectin content elevated and the hydrochloric acid-soluble pectin content reduced. 5) Polygalacturonase activity was at a low level during fruit growth and increased significantly with fruit ripening, while pectinesterase activity was relatively high and changed little during fruit growth and ripening.