A Novel Universal Extraction Buffer for Use in Immunoassay-based Detection of Food Allergens and Gluten

Introduction: Adverse immune responses to food allergens and gluten are relatively common and account for considerable morbidity and mortality. Consequently, the FDA has implemented food labeling requirements to inform consumers of potential health risks. To monitor for allergen and gluten contaminants, analytical food chemistry relies on the use of commercial, immune-based detection kits that isolate target analytes from food matrices utilizing extraction buffers. Considerable disparity exists in the performance of these extraction buffers, furthermore, no single extraction buffer has been advanced that can universally extract gluten as well as all food allergens.

Purpose: To formulate a universal extraction buffer that can efficiently and effectively recover key allergen and gluten residues from complex foods for downstream application in immunobased detection methods, including multiplexed detection assays.

Methods: A panel of complex foods containing milk, eggs, peanuts, tree nuts, shellfish, soy, wheat, and barley residues was compiled. Foods were extracted using our novel universal extraction buffer for 1 min at 95°C or using the commercial extraction buffers supplied by Neogen, ELISA Systems, and ELISA-TEK as per the respective test methods. Protein recovery rates were compared across systems using BCA protein assay, SDS-PAGE analysis, and ELISA.

Results: Extraction of egg, milk, shellfish, gluten, and soy residues using this novel buffer resulted in recoveries of 95-150% relative to the commercial buffers, depending on the food tested or the analytical method employed. In comparison, recovery of tree nut and peanut residues using this buffer was modestly reduced (~50%) relative to the commercial extraction buffers.

Significance: With increased compliance monitoring by FDA, we anticipate a growing need for multiplexed food allergen and gluten detection platforms.  The development of a universal buffer for pan-extraction of food allergen residues and gluten is a critical step in the advancement of multiplexed detection platforms such as Bio-Plex^® and lateral flow devices.