A recent study published in the Journal of Food Protection examined how, when reused, high levels of cashew allergens in frying and roasting oil can transfer to other foods. This sheds light on a potentially overlooked pathway for allergen exposure.
Using bench-scale frying experiments and advanced mass spectrometry, researchers quantified cashew protein residues that accumulated in oil during repeated cashew roasting and were subsequently transferred to other foods cooked in the same oil.
After frying 15 batches of cashews, approximately 70-130 ppm of total cashew protein was detected in the oil. When peanuts and potato chips were then processed in this oil, measurable levels of cashew protein were found in both foods, with substantially higher concentrations observed in potato chips, likely reflecting greater oil uptake and surface porosity. Risk assessments based on internationally recognised reference doses indicated that these concentrations could trigger allergic reactions in a meaningful proportion of cashew‑allergic individuals following typical eating occasions.
The study went on to show that simple oil-cleaning practices used to maintain oil quality can also markedly reduce allergen residues. Fine filtration (11–25 µm) and the use of diatomaceous earth reduced cashew protein concentrations in oil from hundreds of parts per million to below 10 ppm, substantially lowering predicted exposure. This indicates how routine processing steps may play a critical role in reducing food‑allergy risk when applied effectively.
