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- Author or Editor: Tatiána Kaplunov x
Two main methods are in use for packing table grapes (Vitis vinifera) for refrigerated storage and transport. One is to pack the grapes with a sulfur dioxide (SO2) generator pad inside a box with a perforated plastic liner and then to cool them. The other is to place the SO2 pad on the grapes, cool the pallet, and wrap it with low-density polyethylene film, leaving the bottom of the pallet open. These two methods were compared for their efficiency in maintaining grape quality and preventing decay for periods ranging from 33 to 117 days. The experiments included ‘Redglobe’ and ‘Zainy’ grapes packaged in plastic boxes and ‘Thompson Seedless’ grapes packaged in cardboard boxes. The quality of the grapes in the trials with plastic boxes was either similar in both packaging methods or better in the wrapped pallet than the liner method. The pedicels, and sometimes the rachis, showed more desiccation in the liners than in the wrapped pallets. Prevention of decay was also better with the wrapped pallets than for storage in liners. However, in the experiment with cardboard boxes, the externally wrapped boxes contained lower levels of SO2, probably because of absorption of SO2 by the cardboard, and the grapes developed more decay and rachis desiccation than in liners inside the cardboard boxes. The method of wrapping grapes after cooling them can have significant advantages over the liner method because of the faster cooling of the grapes and the use of less plastic-based, nonrecyclable materials.
Grape (Vitis vinifera) storage requires stringent control of gray mold caused by Botrytis cinerea. The commercial practice is dependent on sulfur dioxide (SO2) as a fumigant, which is applied by various means with well-known advantages and disadvantages. Many alternative technologies were developed over the years, most of them with limited efficacy or applicability. Modified atmosphere of table grapes suffers from a narrow threshold between control of gray mold and damage to the berries and stems due to high level of carbon dioxide (CO2) within the film-enclosed package. We demonstrated in the past that dipping table grapes in ethanol after harvest has a very pronounced effect on prevention of decay. However, ethanol does not leave a protective residue within the grapes, so it is not expected to prevent latent infections from developing decay nests during prolonged storage. However, if grapes of cultivar Superior were treated with ethanol and then subjected to a modified atmosphere using plastic films (Xtend), we achieved an additive effect and observed persistent control of gray mold without injury to the grapes. The advantage of this plastic film was mainly in its water conductance, which prevented accumulation of free water that is often the limiting factor in modified atmosphere packaging. This combination results in greater decay control, which is a prerequisite for commercial applicability. If undesired aftertaste did develop within the fruit due to the modified atmosphere, 1 day of exposure to ambient air was sufficient to dissipate it.