Scientific Study

BACKGROUND: Peanuts and tree nut allergies pose an increasing food safety problem. The aim of our study was to test the accuracy of different commercial ELISA kits in the detection of the presence of walnuts in untreated and heat exposed food samples. The evaluation of the effects of thermal treatment in samples was tested exposing walnuts to different heat treatments. All samples were firstly analyzed by two different commercial ELISA assays. Then, we performed Skin Prick test (SPT) on nine patients with proven nuts allergy using small walnut pieces from raw and treated samples. RESULTS: The presence of nuts proteins in thermally processed foods was not accurately detected by ELISA kits. All patients had a positive SPT reaction with raw walnut, while thermal treatments affected walnut allergenicity. ELISA test gives a negative result in case of strong thermal treatment, but at the same time allergic subjects react positive at the stimulation with the same sample. CONCLUSION: This study suggest that commercial ELISA kits may not be able to accurately determine the amount of proteins present in thermally processed foods due to changes in the solubility and immunoreactivity of the target proteins. Finally, the clinical results highlight that thermal treatment might induce a reduction in walnut allergenicity.