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Impact of irradiation of tree nut flours for use in oral immunotherapy

Published online: January 1, 2021

Tree nuts (e.g., hazelnut, walnut, almond, cashew nut, Brazil nut, pecan nut and pistachio nut) are an important source of nutrition and one of the major causes of food allergy affecting >1% of the population. Although oral immunotherapy (OIT) has been approved for the treatment of peanut allergy, there are no FDA-approved treatments for tree nut allergies. A complicating factor of tree nut OIT studies is the high microbial content of commercially available tree nut flours that do not meet FDA guidelines for orally administered drugs.

In a recent study published in The Journal of Allergy and Clinical Immunology: In Practice, Penumarti et al. pioneered a new process for preparing tree nut flours for use in OIT that included gamma irradiation. Gamma irradiation is a type of cold sterilization method which is FDA-approved for use on certain foods to effectively eliminate organisms that cause food borne illnesses. Penumarti et al studied the effect of gamma irradiation on the protein content and bioburden of tree nut flours being investigated for OIT (almond, cashew, hazelnut and walnut).

Gamma irradiation led to a significant decrease of bioburden levels that met FDA standards for aerobic bacteria, mold, yeast, Escherichia coli, and Salmonella. Protein and allergen content did not change significantly during the process. After 24 months of regular testing, bioburden and protein content remained within FDA standards supporting irradiation as a safe and effective method of tree nut flour processing for use in OIT.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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