The effect of dipping pretreatment on ochratoxin A accumulation in sultanas and currants.

The dipping pretreatment on the occurrence of ochratoxin A (OTA) in sultanas and currants was investigated. Grape samples were divided into two groups before a drying process. One group was dipped with potassium carbonate-ethyl oleate, and the other group was left without treatment (the control). OTA were detected using solid-phase extraction clean-up and a high-performance liquid chromatography fluorescence detector. Results showed that OTA content was below the limit of detection in the fresh grapes of both varieties. OTA were not detected in dried vine fruits before storage. However, a real naturally environmental storage revealed that the dipping pretreated samples were contaminated with OTA earlier and to a greater extent than the control. The OTA concentration in the treated and control samples after one-year storage was 0.22 and 0.19 μg/kg for sultanas and 0.34 and 0.21 μg/kg for currants, respectively. These results indicated that dipping pretreatment might increase the toxin contamination and safety risk.