Monitoring peanut allergen in food products by measuring Ara h 1☆☆☆

Abstract 

Background: Peanut allergy is an important health problem in the United States, affecting approximately 0.6% of children. Inadvertent exposure to peanut is a risk factor for life-threatening food-induced anaphylaxis. Objective: The purpose of this investigation was to develop an immunoassay for a major peanut allergen, Ara h 1, to detect peanut allergen in foods so that the risk of inadvertent exposure can be reduced. Methods: A specific 2-site monoclonal antibody-based ELISA was developed to measure Ara h 1 in foods. The sensitivity of the assay was 30 ng/mL. Ara h 1 was measured in foods (n = 83) with or without peanut and in experiments to optimize allergen yield and to determine peanut contamination in spiked foods. Results: Ara h 1 levels in food products ranged from less than 0.1 μg/g to 500 μg/g. Ara h 1 measured in ng/mL was transformed to μg/g for food products. Peanut butter contained the highest amounts of Ara h 1. Peanut extracts contained from 0.5 to 15 mg Ara h 1/g of peanut depending on the extraction conditions. Optimal extraction of Ara h 1 was obtained by using phosphate buffer with 1 mol/L NaCl and Tween at 60°C. Ara h 1 was not always detected in presence of chocolate under the extraction conditions tested. Spiking experiments showed that the assay could detect ~ 0.1% Ara h 1 contamination of food with ground peanut. There was an excellent correlation between Ara h 1 levels and peanut content measured by using a commercial polyclonal antibody-based ELISA (r = 93, n = 31, P < .001). Conclusion: A new sensitive and specific monoclonal antibody-based ELISA was used to monitor Ara h 1 content in food products. This assay should be useful for monitoring peanut contamination in the food manufacturing and processing industry and in developing thresholds for sensitization or allergic reaction in persons with peanut allergy. (J Allergy Clin Immunol 2003;111:640-5.)

Keywords:  Peanut allergen, food allergy, immunoassay, environmental test

Abbreviations:  1% BSA PBS-T , Phosphate-buffered saline containing 0.05% Tween-20 and 1% BSA, ppm , Parts per million, RT , Room temperature, SDS-PAGE , Sodium dodecyl sulfate-polyacrylamide gel electrophoresis