Advances in research on the metabolism of organic acids in citrus fruits

The content of organic acid in citrus fruit is one of the important guidelines deciding the quality of fruit.Reducing the content of organic acid and improving the quality is the hotspot and nodus in research.In this paper the following items,such as anabolism and degradation of citric acid;some related enzymes;the transport of organic acid;measures regulating organic acid content,especially,the latest development in the field of a new utilization of citric acid,citrate homeostasis in citrus juice sac cells and molecular biology,are reviewed.It is speculated that citric acid might participate in the metabolism of amino acid and results in the serious degradation of citric acid.A transport model of citrate3-and H+ is introduced.Finally,the method of regulating organic acid of citrus fruit is discussed and the directions,method and some problems on organic acid metabolism are outlined.