Studies on the Ripening Acceleration of Vapor-Heat Treated Papaya

Polygalacturonase (EC 3.2.1.15) (PGase) and invertase (EC 3.2.1.26) activities were compared with the untreated and the treated papaya thermally injured by vapor-heat treatment. PGase activity was higher in the normal fruits, and invertase activity was only slightly higher in the thermally injured fruits. The appearance of the thermally injured fruits might be caused by the effects of PGase. The rate of ethylene generation was studied by soaking the papaya in a methionine solution of ethylene precursor or an Ethrel (2-chloroethyl phosphonic acid) solution of an ethylene generating chemical. The results showed that the ethylene production rate was relatively higher in fruit treated with an Ethrel solution for both untreated and thermally injured fruits, and a quality improvement of the thermally injured fruit was suggested.