Ochratoxin A in dried vine fruit: method development and survey

Area of Science:

• Food safety analysis
• Mycotoxicology
• Analytical chemistry

Background:

• Mycotoxins, such as ochratoxin A (OA), pose a significant risk to human health.
• Dried vine fruits are susceptible to fungal contamination and subsequent mycotoxin production.
• Regulatory limits exist for mycotoxins in foodstuffs, necessitating reliable detection methods.

Purpose of the Study:

• To develop and validate a method for determining ochratoxin A concentrations in dried vine fruits.
• To assess the incidence and levels of ochratoxin A in retail dried vine fruits in the UK.
• To screen for the presence of aflatoxins in the same samples.

Main Methods:

• Acidic methanolic extraction of mycotoxins from dried vine fruits.
• Immunoaffinity chromatography for selective clean-up of ochratoxin A.
• High-performance liquid chromatography (HPLC) with UV detection for quantification.
• HPLC coupled with mass spectrometry (MS) for identity confirmation.
• Analysis of 60 retail samples of currants, raisins, and sultanas purchased in the UK.

Main Results:

• The developed method achieved a limit of detection of 0.2 µg/kg for ochratoxin A with recoveries between 63-77% at 5 µg/kg.
• Ochratoxin A was detected in 88% of the analyzed dried vine fruit samples (19/20 currants, 17/20 sultanas, 17/20 raisins).
• The maximum ochratoxin A level found was 53.6 µg/kg; no aflatoxins were detected (limit of detection 0.2 µg/kg for B1, B2, G1, G2).

Conclusions:

• Ochratoxin A is widespread in UK retail dried vine fruits, frequently exceeding the method's limit of detection.
• The described method is effective for the accurate determination and confirmation of ochratoxin A in dried vine fruits.
• Further monitoring and risk assessment are warranted due to the high incidence of ochratoxin A in these commodities.