Effect of different treatments on the evolution of polyamines during refrigerated storage of eggplants

The applicability of a thermal treatment was compared with modified-atmosph ere (MA) storage in relation to chilling injury (CI) and polyamines evoluti on in eggplants. Fruits underwent physiological disorders at 3 degreesC, ev idenced by the appearance of surface injuries at the third day of storage, and, after moving the fruits to 20 degreesC, by increased respiratory activ ity and more intense ethylene production. Storage of fruits in sealed low-d ensity polyethylene bags and a previous treatment with heated air (1 h at 3 5 degreesC) were both effective in retarding chilling injury, though the fo rmer was better. Two free polyamines were found in cv. Black Nite: putresci ne, in greater proportion, and spermidine. Putrescine increased in control (untreated) fruits stored at 3 degreesC in parallel with the external appea rance of chilling injury, whereas this increase was either not exhibited or retarded in treated or MA stored fruits. Spermidine did not change in cont rol fruits at 3 degreesC, remaining almost constant over the whole storage period, whereas in heat- and MAP-treated fruits spermidine levels exhibited a decrease.