Effects of oxalic acid compound cleaning agent on washing efficiency and post-harvest physiology of apples.

In the present study effects of oxalic acid compound agent on washing efficiency and post-harvest physiology of fruits of apple cv.Red Fuji were investigated.This compound is a mixture composed of 10.0 g·L-1 oxalic acid,10.0 g·L-1 sodium chloride,9 mg·kg-1 chlorine dioxide and 0.02% Tween-20.Usage of this compound as a washing agent was much more efficient than control in clearing pesticides,heavy metals and colonies from fruit surface and the clearance rate could reach 76.39%～83.24%,62.48%～91.29% and 80.64%,respectively.Compared with control in cool storage conditions,the treatment of this compound decreased the respiration rate and ethylene production,delayed the respiration and ethylene peaks,increased superoxide dismutase(SOD),peroxidase(POD) and catalase(CAT) activities,and slowed down the increase of malondlaldehyde(MDA) content and the relative membrane permeability,thereby reducing the extent of lipid peroxidation.In conclusion,usage of oxalic acid compound as a washing agent can greatly clear the pesticides,heavy metals and colonies,improve quality and delay aging of stored apple fruits.