[Comparison of three methods for screening aflatoxin-producing strains]

Area of Science:

• Food Science
• Microbiology
• Analytical Chemistry

Background:

• Aflatoxins are toxic secondary metabolites produced by Aspergillus species.
• Contamination of foodstuffs by aflatoxin-producing fungi poses a significant food safety risk.
• Accurate detection of aflatoxin-producing strains is crucial for food quality control.

Purpose of the Study:

• To evaluate and compare the efficacy of three methods for screening aflatoxin-producing Aspergillus flavus strains.
• To determine the prevalence of aflatoxin-producing strains in foodstuffs from Zhejiang province.
• To identify the most reliable and practical method for routine screening.

Main Methods:

• Screening of 76 Aspergillus flavus strains using rice medium microcolumn, aflatoxin-producing ability medium dish (APA), and A and M medium thin-layer chromato scanner (AM) methods.
• Confirmation of aflatoxigenic strains using thin-layer chromatography.
• Analysis of false positive and false negative rates for each method.

Main Results:

• Aflatoxin-producing strain rates varied: 11.8% (microcolumn), 9.2% (APA), and 18.4% (AM).
• Twenty strains (26.3%) were positive by all three methods.
• The AM method exhibited the highest accord-rate with other methods, despite showing false positives; APA method had the highest false negative rate.

Conclusions:

• All tested methods exhibited limitations, including false negatives and positives.
• The AM method is suggested as a safe, simple, and reliable screening tool for aflatoxigenic strains, with potential for improvement.
• Understanding method-specific errors is vital for accurate aflatoxin risk assessment in food.