Ripening of plum fruit : GreenCHAINge Fruit & Vegetables WP6

Abstract

Ripening of plums, from South Africa (SA), was studied following reefer transportation. In experiment 1, plum cultivars ‘Pioneer’ and ‘African Rose’ were ripened using different temperature scenarios. Both cultivars showed increased coloration during ripening, but this was much more pronounced in ‘Pioneer’ compared to ‘African Rose’. In ‘Pioneer’ there was a clear decrease in firmness during ripening; this was correlated with the temperature sum. At a temperature sum of 100-120 degree-days, the fruit had soften completely and reached the “ready–to-eat” stage. Increasing the temperature sum did not further soften the fruit. Irrespective the temperature scenario, ‘African Rose’ showed no softening and did not become “ready-to-eat”. In experiment 2, plum cultivars ‘ So ngold’ and ‘Southern Belle’ were harvested three times during their production season, transported to the Netherlands (NL), and ripening was studied at three temperatures (16, 20 and 24°C for 2 days). ‘So ngold’ was always less firm at arrival compared to ‘Southern Belle’. The applied temperatures did not have a clear effect on the speed of ripening. Fruit firmness at arrival was similar for the different batches of each cultivar; fruit from later harvest batches showed slightly more softening during storage and shelf life than fruit from first harvestbatch. Ethylene treatment (100 ppm, 24h) had effect on firmness loss in ‘Southern Belle’ when plums were ripened at higher temperature (ethylene effect was not tested in ‘So ngold’). Ethylene production in ‘Songold’ was about ten times higher than in ‘Southern Belle’ and increased during ripening in both cultivars. No clear effect of ripening temperature on ethylene production was observed.