Plum Fruit Packed in Flow Packs with Absorbent Pads and Stored at Different Temperatures

The shelf life of plum fruit (Prunus domestica) is limited due to among other factors fungal fruit decay. Absorbent pads (“fruit pads”) are commercially used today in order to absorb juice from the berries and condense water and hence reduce fungal growth. The aim of this experiment was to evaluate the effect of different types of absorbent pads on weight loss, decay and quality for plum fruit under realistic storage conditions. Plum fruit (‘Reeves’ and ‘Jubileum’) were delivered at a commercial packing house, packed in trays on a flow packaging machine with three different types of absorbent pads placed at the bottom of the trays (standard fruit pad and two humidity control pads with different active compounds; denoted active pad 1 and 2). Trays without pads were controls. After packaging, plums were stored at 3 or 6°C for 7 days and thereafter 2 days at 20°C. Fruit quality, weight loss and amount of fungal decay were recorded at the end of the storage period. The different pads had no significant effects on ripeness state measured by DA-meter and fruit firmness measured at end of storage. The pads had significantly different effect on weight loss, and for ‘Jubileum’ the weight loss was 1.5% for the active pad 1, 2.5% for the active pad 2 and below 1% for the standard pad and the control. Significant effects were found for cultivar and absorbent pads on the total amount of decayed fruit. ‘Jubileum’ was more vulnerable to decay than ‘Reeves’, and the active pad 2 had the lowest number of decayed ‘Jubileum’ fruit stored at 3°C. More work and a cost-benefit analysis should be performed before absorbent pads are recommended for plum fruit.