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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Commodity Protection and Quality Research » Research » Publications at this Location » Publication #172356
Title: QUALITY OF 'THOMPSON SEEDLESS' TABLE GRAPES FUMIGATED WITH CO2+SO2 AND METHYL BROMIDE.

Author
item MITCHAM, ELIZABETH - UC DAVIS
item Leesch, James

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/4/2004
Publication Date: 11/10/2004
Citation: Mitcham, E., Leesch, J.G. 2004. Quality of 'thompson seedless' table grapes fumigated with co2+so2 and methyl bromide, November 10-12, 2004, Sydney, Australia.

Interpretive Summary: Table grapes treated with CO2+SO2 and methyl bromide in 2 separate fumigations showed that the storage and treatment temperatures were more important than the fumigations in affecting the quality of the grapes. The grapes treated and held at the higher temperature of 19.5C were more affected than those treated at 14C. Thus treatments at the lower temperature is preferred to that at the higher temperature.

Technical Abstract: California table grapes must be fumigated with 6% CO2 plus 1% SO2 for 30 minutes for control of black widow spiders and with 40 g/m3 methyl bromide for 2 hours for control of other arthropod pests prior to shipment to Australian markets. The affect of this combination treatment on the quality of the grapes had not been fully evaluated prior to this study. 'Thompson Seedless' table grapes were harvested into bags at two maturities and packed into corrugated plastic boxes. One half the boxes had an SO2 pad and liner and the remainder did not. Grapes were fumigated with methyl bromide at 14°C (48 g/m3) or 19.5°C (40 g/m3) for two hours and 6% CO2 + 1% SO2 for 30 minutes alone, and either preceding or following methyl bromide fumigation at 19.5°C. Grape quality was measured after simulated air shipment (2 days at 5°C) or sea shipment (21 days at 2.2°C) and after a marketing period (2 days at 20°C). Grape quality was more affected by holding temperature than fumigant treatment. Fruit held or fumigated at 14°C had less berry browning and rachis and stem browning than fruit held or fumigated at 19.5°C, indicating that quality was more affected by exposure to warm temperatures than by the fumigants themselves.