Food manufacturers rely on environmental swabs to confirm that cleaning procedures in production facilities are effective and that no unintentional food allergens remain on surfaces or in products. These swabs are typically sent to third-party laboratories for analysis. However, delays in shipping and variations in storage temperature can affect how well allergen residues are recovered from the swabs, potentially impacting the accuracy of allergen detection.
A recent study evaluated how storage conditions influence the recovery of peanut, milk, and gluten residues from environmental swabs. Researchers spiked swabs with known amounts of allergenic proteins and stored them at room temperature, 37°C, 4°C, and −20°C for up to 14 days. The swabs were then analysed using two commercial ELISA kits. Results showed that recovery of allergen residues was higher and more stable when swabs were stored at colder temperatures, particularly at 4°C or −20°C. The choice of ELISA kit also mattered, with one kit consistently outperforming the other in maintaining reliable detection over time.
These findings highlight the importance of proper storage and transport of swabs to ensure accurate allergen monitoring in food production. While the study focused on specific swab and kit types, it underscores the need for further research to confirm whether these results apply to other allergens and testing methods. Current best practice recommends shipment on ice with same-day delivery and keeping samples cold until analysis. These measures are key to safeguarding food safety and consumer confidence.
Reference: Humphrey, et al. 2025. Effect of storage time and temperature on the recovery of peanut, milk, and gluten residue from environmental swabs. Journal of Food Protection, 88(12), p.100645. Available at: DOI: 10.1016/j.jfp.2025.100645.
