Resumen de Chlorophyll degradation and resulting catabolite formation in stored Japanese bunching onion (Allium fistulosum L.)

Prasajith K Dissanayake, Naoki Yamauchi, Masayoshi Shigyo

• BACKGROUND: Loss of green colour is the main factor in quality deterioration of stored Japanese bunching onion (JBO, Allium fistulosum L.) leaves. Elucidation of chlorophyll (Chl) degradation has not been performed to date. In the present study, Chl catabolism and Chl-degrading enzyme activities in stored JBO leaves were investigated. RESULTS: Green leaves of JBO stored at 25 °C turned yellow within 3 days, whereas no changes occurred at 4 °C. Pheophytin (Phy) a, chlorophyllide (Chlide) a, pheophorbide (Pheide) a and C132-hydroxychlorophyll (OHChl) a were the main catabolites of Chl a and diminished at 25 °C concomitant with leaf yellowing, whereas no significant reductions were observed at 4 °C. The activities of Chl-degrading peroxidase and Mg-dechelation increased significantly at 25 °C but not at 4 °C. CONCLUSION: Chl degradation was accelerated and catabolite levels (mainly Phy a, Chlide a, Pheide a and OHChl a) were diminished in JBO leaves stored at 25 °C, suggesting that the catabolites are rapidly converted into their following forms. Activities of Mg-dechelation and Chl-degrading peroxidase were significantly enhanced during storage at 25 °C, indicating that these two enzymes have major roles in Chl degradation in stored JBO leaves. Copyright © 2008 Society of Chemical Industry