Reports indicate that aflatoxin contamination in almonds comprise a few highly contaminated kernels among a much larger bulk with low concentrations, hypothetically due to cross‐contamination during processing. To test this, kernels exhibiting this distribution were generated by distributing 141.5 µg of aflatoxin between 20 almonds (approximately 7 µg each) which were then mixed with 5 kg (approximately 4,000 kernels) of local raw unroasted almonds for 20 min using an industrial mixer. A second 5 kg lot of noncontaminated kernels was marked for later identification then similarly mixed with the contaminated group. The groups were re‐separated and aflatoxin content was measured using High Performance Liquid Chromatography (HPLC) analysis. Twenty‐three micrograms of aflatoxin was recovered from the initially noncontaminated group, indicating cross‐contamination during mixing. Approximately 0.10 µg of aflatoxin was recovered from equipment surfaces. The results emphasize the need to reduce the potential for cross‐contamination between nuts by removing contaminated nuts and routinely cleaning processing equipment.
Practical applications
Shelled almonds have an atypical aflatoxin distribution that appears consistent with a combination of two distributions: first, infrequent highly contaminated nuts and second, a uniform low‐level aflatoxin contamination. This second distribution appears to come from cross‐contamination during postharvest processing, but this has not been previously tested. Results of this study confirmed that aflatoxin can transfer between contaminated nuts and uncontaminated nuts via simple mechanical mixing contact, as would occur during postharvest processing. Almond producers will want to take this finding into account when reviewing their processing and cleaning procedures and reduce any opportunity for nut to nut cross‐contamination by removing contaminated nuts as early as possible and routinely cleaning processing equipment.
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