Hort symposium
Handle with care
It’s the little things in picking and packing that can kill cherry quality. By Susan McIver
T
he dollars are in the details. Such was the message Peter Toivonen had for cherry growers at the 2012 Horticultural Symposium held in Kelowna in early March. A research scientist at the Pacific Agri-Food Research Centre in Summerland, Toivonen specializes in post-harvest physiology.
“Getting quality cherries into the box and to the customer starts in the field,” he said. “”Half of the defects in cherries are caused by incorrect picking and the other half are associated with the packing line.” In order to help prevent compression bruising, Toivonen recommends teaching pickers how to remove cherries by the stem rather than grabbing them.
It is also important that flexible plastic buckets or foam pads in rigid containers be used.
Cherries should not be dropped from a distance greater than eight inches into either the buckets or the water bath in the packing line. Compression injuries can also be caused when the fruit is jostled during transport to the packing line. Once picked, fruit should be kept out of the sun and cooled as soon as possible.
Covering the fruit helps to keep the humidity high, the temperature down and reduces shrinkage and decay in storage.
If using a white shade cloth, Toivonen stressed the need to use potable water to keep the humidity at optimum level.
“One little thing in the field can have a big effect,” he said. Once fruit is packed, attention should be given to keeping the temperature in the boxes, especially those near the centre of a pallet near
SUSAN MCIVER
Peter Toivonen, left, post-harvest physiology specialist, discusses techniques for reducing compression injuries in cherries with Kelowna orchardist Neil Denby.
zero degrees C.
After being picked and packed, cherries continue to respire and produce heat.
Toivonen said that even a well designed hydro-cooling system will not allow for cooling fruit lower than 3 to 5 C in the box.
Also, cooling systems in trailers and containers are designed to reduce the temperature around the boxes, not in them.
The key to optimum cooling is to allow for air flow around the boxes either by how they are stacked, such as in a pyramid formation, or by use of a forced air system.
Either way produces similar positive results, according to Toivonen. Keeping the box temperature at 3C or less is essential to minimize the number of soft cherries which are more susceptible compression injury. Good temperature management will
lead to overall good quality retention for up to six weeks in storage or shipping.
This is especially important in view of fruit being shipped over long distances and probably by sea in the future.
Susceptibility to compression injury and softening of the fruit is also determined by the colour stage maturity and soluble solids content. Toivonen said a harvest maturity 5 on the CITLF scale and a sugar content of approximately 20 per cent yield good results.
Pruning and orchard management for an open canopy is also helpful. Better light penetration results in higher sugar content and, according to data from Chile, firmness is improved with high light concentration.
“Get back into the field and look at light penetration,” Toivonen advised.
AGRICULTURAL NETS & FABRICS
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250.494.1099 British Columbia FRUIT GROWER • Summer 2012 15
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