Research On Physiology Of Wax Apple During Postharvest Storage

Wax apple with beautiful shape and rich nutrition is loved by consumers for not only the unique flavor, but also the diet therapy efficacy. However, wax apple is difficult to storage because its tender tissue and exuberant breathe metabolism. If wax apple is not handled in a timely manner after harvest, the edible quality of it will sharply deteriorate, and then it will lose commercial value. This paper aims to research the physiological changes, organic acid metabolism, cell wall degrading enzyme activities and organizational structure changes of wax apple, and compare low temperature (5℃) to normal temperature (25℃) for the effect to the storage. We can explore the physiological process of wax apple and the effect of low temperature for storage. The results show that:During storage period, the firmness of wax apple was becoming smaller, and the weightlessness rate and juice yield kept increasing, and the membrane permeability also showed a rising trend. Respiration rate of wax apple achieved the peak twice. Ethylene release ascended firstly and declined finally. Low temperature storage(5℃) can effectively reduce weightlessness rate and membrane permeability of wax apple fruits, and restrain respiration rate and ethylene release of wax apple.The organic acids in wax apple are malic acid, oxalic acid, ascorbic acid, lactic acid, acetic acid, citric acid, etc. The mainly organic acid is malic acid, accounting for approximately 70%. Low temperature can decrease organic acid loss effectively. Throughout the storage period, total sugar content, as the same as sugar acid ratio, presented the first decline after rising trend. Low temperature can delay the process of sugar metabolism.The activities of polygalacturoneses (PG) and cellulase (Cx) of wax apple changed in a fluctuated rising trend. The activity of pectinmethylesterases (PME) showed a rising trend, and the content of soluble pectin content continuously increased with the protopectin content lowering and the fruit firmness declined. Low temperature can delay the emergence of peak value of enzyme activity and the transform process of pectin.The changes of wax apple fruit organizational structure were observed by paraffin sections. We found that organization structure ruptured gradually and shrink intensified with the cells broken down. Low temperature can well maintain the integrity and the stability of the cellular structure.In summary, low temperature can keep the quality of wax apple and delay its mature and aging and is positive to the preservation of wax apple.