Walnut Food Allergenic Extracts

Abstract

Total protein extractability and IgE binding are useful methods for determining potency of allergenic extracts. These techniques were applied to investigate various production methods for walnut food extracts. English walnut food extracts were made to evaluate source material, defatting, extraction fluid, and processing. Protein content was tested by Bradford and SDS-PAGE. IgE binding was determined by Immunoblotting and microtiter plate ELISA titration using sera from walnut sensitive patients. Walnut food extracts can show a more than 100 fold variability in total protein depending on the extraction process. Aqueous extraction shows the lowest total protein content and 50% glycerin with blending greatly improves the extractability of protein. Total protein correlated to the ability to bind IgE with levels below 0.3mg/mL showing negative IgE binding with moderately sensitive serum (<17kU sIgE). Walnut extract IgE binding potency is dependent on the presence of glycerin during processing.