Recovery of Aflatoxin B1 in a Range of Food Commodities Utilizing a Matrix Resistant ELISA

Introduction:  Aflatoxin B₁ is a well-known potent human carcinogen produced by toxigenic fungi.  Given its ubiquitous presence in a wide variety of foods and beverages, aflatoxin B₁ levels must be measured and monitored to prevent contaminated food from reaching the consumer.  Enzyme linked immunosorbent assays (ELISAs) are frequently employed as a rapid and inexpensive method to screen samples that may contain aflatoxin B₁ concentrations above the legal permissible limit.  To date, many available ELISAs are limited in the range of commodities that can be tested because they are subject to matrix interferences and require an additional clean-up step.

Purpose:  The aim of this study was to evaluate if a single ELISA kit can accurately detect aflatoxin B₁in commodities that typically pose matrix interferences, including nuts, spices, and other common cooking ingredients.

Methods:  The various comestibles (almonds, macadamia, peanuts, chili, cinnamon, coriander, ginger, and coconut) were purchased from local markets and evaluated for matrix interferences.  A Student’s t-test was performed to determine any significant differences between the extracted commodity and extraction solvent alone.  Samples were then fortified with aflatoxin B₁at various concentrations ranging from 2.5 – 20 ppb (n = 3 for each spike level) and measured in three independent experiments by a previously developed competitive inhibition ELISA.  The % recoveries and %CVs were calculated.

Results:  All food items exhibited minimal matrix interferences.  The mean signal of the commodities did not demonstrate a statistically significant difference compared to the mean signal of the extraction solvent alone (P < 0.05).  All commodities showed excellent recoveries of 82 - 111% with %CVs of less than 13%.  The only exception was cinnamon, which had a recovery of less than 30%.

Significance:  The data demonstrates that a single ELISA kit can be used to successfully quantify aflatoxin B₁ in most commodities without the need for special extraction methods or clean-up procedures.