Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS

Effect of post-harvest treatments on OTA content in table grapes

The number and type of isolates and their ability to produce OTA was determined at harvest, after 7 days at 20ºC and after 30 d at 0ºC in the presence of SO2 generator pads and 2 days at 20ºC, with and without ethanol dips. The results show that ethanol dips did not reduce the number of Aspergillus isolates that were recovered from the berries at any of the storage regimes. An increase in the number of isolates was observed in 2 of the samples at storage of 20ºC indicating neither the ethanol treatment and storage conditions were capable of coping with a situation of decay development.

In experiments hold under commercial simulation of storage, grapes of cv. Superior were stored at 0ºC for 45 days. Control, untreated grapes suffered decay and the healthy berries were sampled in addition to ethanol-treated berries and berries which were exposed to SO2 generator pads. No isolates could be recovered from the SO2-treated berries. Both the ethanol and control treatments contained A. niger and A. carbonarius on the berries and most of the later isolates were OTA positive. Berries of cv. In addition, Red Globe were exposed to different levels of SO2. The results of the natural in vivo contamination of the berries showed that the control untreated grapes were contaminated by both biseriate isolates and A. carbonarius.

An low level of 0.5 ppm SO2 in the package reduced the amount of isolates that were recovered from the berries whereas a level of 5 ppm no isolates could be recovered from the berries. In this experiment, Petri dishes containing A. niger and A. carbonarius were introduced to packages immediately after spreading the spores on Rose-Bengal medium. After 12 days at 0ºC storage plates were incubated at 25ºC and the number of fungal colonies was counted. The results show that a level of 0.5 ppm SO2 reduced the amount of A. carbonarius to quarter and A. niger to half of the control. No isolates could develop on plates that were exposed to 5 ppm of SO2.

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Reported by

The Agricultural Research Organisation of Israel - The Volcani Centre
Department of Postharvest Science, ARO, The Volcani Center
50250 Bet Dagan
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