Do fumonisin mycotoxins occur in wheat?

Area of Science:

• Food Science
• Mycotoxicology
• Analytical Chemistry

Background:

• Fumonisins are mycotoxins primarily produced by Fusarium fungi, which are maize pathogens.
• While fumonisins are common in maize and its products, reports of their presence in wheat are occasional.
• Previous studies suggested fumonisin presence in South African wheat, necessitating further investigation.

Purpose of the Study:

• To investigate the reported natural occurrence of fumonisins in the 2003/2004 South African wheat crop.
• To validate and confirm findings using a definitive analytical technique.

Main Methods:

• A modified AOAC International high-performance liquid chromatographic (HPLC) method, originally for maize, was validated for wheat.
• Immunoaffinity column cleanup and direct fluorometric measurement were used in initial screening.
• HPLC analysis was performed on 30 wheat samples previously reported as positive for fumonisins.

Main Results:

• No detectable fumonisins (<5 microg/kg) were found in any of the 30 analyzed wheat samples.
• The results contradict previous reports of fumonisin presence in wheat.
• Screening methods, especially when used outside their matrix of applicability, can yield false positives.

Conclusions:

• The investigation casts doubt on previous reports of fumonisins in wheat.
• It underscores the critical importance of validating screening results with definitive techniques.
• Accurate mycotoxin detection in food matrices requires careful method selection and validation.