Irradiated Tree Nut Flours for Use in Oral Immunotherapy.

Abstract Background Tree nut allergies affect an estimated 1% of the United States population and is lifelong in 90% of allergic individuals. Oral immunotherapy (OIT) for food allergies is an effective method to induce desensitization in a majority of participants in trials of peanut, egg, and milk OIT. Limited trials using tree nut OIT have been reported, possibly due to the lack of standardized drug products. Objective Food products used in OIT are considered drugs by the FDA since they are intended to modulate the individuals’ immune responses to the food allergens. As such, OIT drug products must meet FDA standards for acceptable levels of microbes and undergo testing for allergenic proteins. We aimed to determine the suitability of walnut, cashew, hazelnut, and almond flours for use in OIT trials. Methods We employed gamma irradiation on commercially available walnut, cashew, hazelnut, and almond flours and tested their levels of microbial contamination, total protein and allergen content, along with stability of these parameters over time. Results Our results demonstrate that irradiation of tree nut flours greatly diminishes the levels of total aerobic bacteria, mold, yeast, E. coli, and salmonella, while there are no substantial changes in total protein or allergen content. Importantly, the microbial levels, protein, and allergen content remained stable over a 24 month period. Conclusion Irradiation of tree nut flours is a safe and effective method of processing to allow tree nut products to meet the FDA standards for OIT drug products.