Sulphur pads extend storage period for table grapes

Thursday, May 28, 2015

by SUSAN MANN

Scientists at Vineland Research and Innovation Centre have found a way to increase the storage time for fresh table grapes.

Normally fresh sovereign coronation grapes can only be stored for two weeks after harvest, says Kimberley Cathline, senior research technician with the centre. But when the grapes are being harvested, from late summer to early fall, growers face a local market saturated with other produce, both local and imported.

The Vineland centre’s post harvest team was able to extend the fresh grapes’ storage time to five weeks after harvest using sulphur dioxide-generating pads during the grapes’ storage. The research was done last year and funded by the Ontario Fresh Grape Growers’ Marketing Board and the Ontario Farm Innovation program, through Growing Forward 2.

The main factor causing the grapes’ quality to deteriorate during storage is water loss, “which then causes stem browning and then the growth of the grey mold, botrytis. Those two things happen within two weeks and the grapes are usually not marketable then,” she says. But the sulphur pads help to keep the stems green and “it also kills the spores of the fungus so you don’t get the spread of that fungus very fast at all.”

Cathline says the sulphur dioxide pads are available for use now and the marketing board has details on how farmers can buy them.

Fresh grape growers in the United States, Chile and other parts of the world use the sulphur pads, she notes.

The centre will be doing additional research by studying the use of sulphur dioxide fumigation during storage. That might extend the storage time even longer than five weeks. Cathline says they’ll be applying for funding for that project this fall. BF