ENDOGENOUS POLYAMINES IN ‘NAM DOK MAI’ MANGOES WITH DIFFERENT RIPENING STAGES AND ITS RELATION TO CHILLING INJURY DURING STORAGE

Free polyamines (putrescine; Put and spermidine; Spd) and chilling injury (CI) symptom were investigated with ‘Nam Dok Mai’ mangoes at different ripening stages: 1) treated by acetylene gas 2 days (stage 2) and 2) 4 days (stage 3) after harvest and 3) non-treated (stage 1). Fruits were kept under either 5°C or 13°C for 45 days. The result showed difference in polyamine levels among the three stages. For the stage 1 fruit, Put level increased reaching to the maximum values during 15-day storage at 5°C and then it decreased, followed by stage 2 and stage 3 with a similar trend. In contrast, stage 2 and stage 3 fruits kept at 13°C had higher Put levels than stage 1. Spd levels in stage 2 and stage 3 fruits trended to decrease with storage time, while stage 1 fruit increased after 15-day storage. However there were no great variations in the ripening stages after 30 days in storage. When fruit were transferred to 25°C for ripening, Put and Spd levels decreased in all ripening stage fruits. The possible relationship between polyamine content and chilling injury at different stages could be imply in the mango fruit exposed to chilling temperature. Furthermore some other physicochemical changes such as factors affecting chilling injury incidence will be discussed.