Pecan (Carya illinoinensis) detection using a monoclonal antibody-based direct sandwich enzyme-linked immunosorbent assay

Abstract

A commercially available (BioFront Technologies) monoclonal antibody-based direct sandwich enzyme-linked immunosorbent assay (ELISA) for pecan detection was evaluated. The assay can detect 0.5 ppm of pecan and reliably quantify >1.5 ppm of pecan with <14% intra- and inter-assay variabilities. The detection antibody did not exhibit cross-reactivity with 155 foods/ingredients tested at 100,000 ppm, although it registered 0.6% and 0.8% cross-reactivity with 10,000 ppm of English walnut and black walnut, respectively. The target antigen was stable against autoclaving, blanching, frying, microwaving, and roasting. The antigen was detected in a variety of food matrices with 80.5–111.6% and 22.2–154.5% recoveries for pecan-spiked and incurred samples, respectively. The assay did not yield any false negative results among tested commercial and in-house prepared samples, however, it recognized two commercial products with declared walnut and no declared pecan as positive. In conclusion, the ELISA was sensitive and robust for pecan detection and quantification and was specific other than the low level of cross-reactivity with walnut species.