Objectives: Allergens can be introduced into food due to cross contact during manufacture, resulting in a potential food safety hazard to consumers with food allergies. Deep frying is a common food preparation method, and frying oil is often reused. While filtration methods are utilized to regenerate the oil, it is unknown how effectively such measures remove allergens.<br/>Methods: Before evaluating the effectiveness of filtration, a method for allergen extraction from oil was first validated by mixing peanut flour (50% protein) into oil at 50–1,000 µg/mL and extracting with PBS, sodium bicarbonate, or acetone. Concentrations of peanut protein were determined by ELISA. Peanut flour was then mixed into oil at 1,000 µg/mL and heated for 0–10 min at 191°C. A portion of the oil was filtered using filters of varying pore sizes (11 µm–2 mm). Peanut protein was extracted, and concentrations were determined by ELISA and compared to determine the effects of filtration and frying time.<br/>Results: Acetone precipitation best extracted peanut protein with recoveries of ≥ 100%. The three methods performed similarly at 1,000 µg/mL peanut flour, but PBS and bicarbonate extractions were less effective at lower peanut flour concentrations. For the filtration studies, as pore size of the filters decreased, less peanut protein was detected in frying oil. However, up to ~60% of peanut protein was detected in oil filtered even at the smallest pore size of 11 µm. The amount of detectable protein in oil decreased with increased frying time, with &lt;10% detectable after 10 min.<br/>Conclusions: Although some filtration treatments reduced peanut protein levels, varying concentrations still remained in frying oil which may result in allergen cross-contact in other foods prepared in it. Since frying decreased the amount of peanut protein detectable by ELISA, alternative methods are needed to determine whether these proteins are still present.

Efficacy of filtration methods in removing peanut protein from frying oil

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ACS Fall 2022

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