Hydrogen peroxide-induced pericarp browning of harvested longan fruit in association with energy metabolism.

Energy metabolism of "Fuyan" longan fruit treated with hydrogen peroxide (H2O2), the most stable of the reactive oxygen, and its relationship to pericarp browning were investigated in this work. The results displayed that H2O2 significantly decreased contents of adenosine triphosphate (ATP) and adenosine diphosphate (ADP). It also inhibited activities of H+-ATPase, Ca2+-ATPase and Mg2+-ATPase in membranes of plasma, vacuole and mitochondria during the early-storage and mid-storage (except for mitochondrial membrane Mg2+-ATPase). These results gave convincing evidence that the treatment of H2O2 accelerating pericarp browning in harvested longans was due to a decrease of ATPase activity and available ATP content. This might break the ion homeostasis and the integrity of mitochondria, which might reduce energy charge and destroy the function and compartmentalization of cell membrane. These together aggravated browning incidence in pericarp of harvested longan fruit.