Study on the post-harvest metabolism of organic acids in fruit of Guanxi-miyou pomelo cultivar

ZHANG Xiao-hong; ZHAO Yi-jie; PAN Dong-ming; LIN Hang

Abstract：The contents of organic acids and the activities of organic acid-metabolizing enzymes,including citrate synthase(CS),phosphoenolpyruvate carboxylase(PEPC),Cyto-Aconitase(Cyto-Aconitase)and NAD-isocitrate dehydrogenase(NAD-IDH)were measured in the fruit of Guanxi-miyou pomelo cultivar after harvest and probed their interrelationships and the mechanism of the organic acid metabolism. The results showed that the fruit went sour when stored at room temperature. The citric acid in the fruit greatly accumulated and peaked 70 days after harvest and then declined slightly. Correlation analysis showed that a significant positive correlation was observed between the content of citric acid and the activity of CS,while there was a significant negative correlation between the content of citric acid and the activity of NAD-IDH/ Cyto-Aconitase. Storing at low temperature of 6 ℃,the content of citric acid in the fruit declined on the whole. The content of citric acid had a significant positive correlation with the activity of PEPC. It is suggested that CS,PEPC and NAD-IDH/ Cyto-Aconitase were the main enzymes in organic acid accumulation of Guanxi-miyou pomelo fruit. We concluded that storing at low temperature of 6 ℃ could effectively solve the problems of the fruit acidification after harvest.