Effects of storage temperatures on polyamine content of some leafy vegetables.

Effects of storage temperatures on polyamine content in buds of broccoli (Brassica oleracea var. italica, cv. Chaster), fourth leaf of senpo-sai (Brassica napus), and cotyledons of the Japanese radish, kaiware daikon (Raphanus Sativus L.) were investi-gated to ascertain the possibility of the polyamines, putrescine and spermidine, being in-dicators of chemical changes during storage. The combination of perchloric acid extrac-tion and post-column HPLC provided recoveries ranging from 84.5 to 105.2%, proving to be a useful procedure for routine assay for polyamines. Chlorophyll and polyamine levels in the broccoli and the kaiware daikon decreased during storage at 20°and 23 °C, re-spectively, whereas at 2 °C, chlorophyll and spermidine tended to remain nearly constant while putrescine increased. In the fourth leaf of senpo-sai, a decrease in chlorophyll and an increase in putrescine were observed during storage at 23 °C. These variations in polyamines in these vegetables during storage indicate that polyamines are not as good an indicator of chemical changes as chlorophyll.