Role of oxidative enzymes on the darkening induced by chilling of arracacha roots - DOI: 10.4025/actasciagron.v30i1.1129

Abstract

In this experiment roots of arracacha (Arracacia xanthorrhiza Bancroft) were stored at temperature of 5 and 10ºC for 28 days. At every seven days, the roots were removed from the cold storage and visually analyzed for the presence of chilling symptoms. Afterwards, the roots were grinded for polyphenoloxidase, peroxidase activities and soluble phenolic compounds. Both temperature of 5 and 10ºC induced external and internal darkening of the roots, with higher intensity at 5ºC. Activities of polyphenoloxidase, peroxidase and content of phenolic compounds were enhanced at cold storage. Activity of polyphenoloxidase and content of phenolic substances increased up to the 14^th day of storage in both temperatures. The activity of peroxidase was elevated up to the seventh day of storage in both temperatures, which was kept constant at 5 and at 10ºC. The highest activity was detected at the 14^th day of storage. These results show that peroxidase is involved in the initial stress response to the harvest and chilling, followed by the involvement of polyphenoloxidase in the enzymatic darkening and accumulation of phenolic compounds in the tissues