Date of this Version
Pecan nuts are becoming increasingly popular due to their link to health benefits. However, the presence of undeclared pecan residues in food products can pose serious health risks for pecan-allergic consumers. Currently, analytical methods for the detection of pecan allergens are limited and have not been validated for use by the food industry to assess the effectiveness of allergen control programs. Therefore, the aim of this study was to develop a sandwich-type ELISA to detect and quantify allergenic pecan residues in processed foods. Several varieties of pecan were mixed, roasted, and ground to immunize a goat, sheep, and rabbits. The pecan-specific IgG titer and specificity of the IgG antibodies produced in the 3 species of animals were tested by direct ELISA and immunoblot, respectively. Goat and rabbit polyclonal anti-roasted pecan sera were used as capture and detector reagents, respectively, to develop the sandwich ELISA, with visualization through an alkaline phosphatase-mediated substrate reaction. The pecan ELISA had a limit of quantification of 2 ppm (2 μg pecan/g). Because pecans are commonly used in confections and bakery products, sugar cookie, vanilla ice cream, and dark chocolate matrices were chosen to evaluate potential interference on the ELISA’s performance using spike and recovery approaches. The matrices did not significantly (p < 0.05) affect the sensitivity of the developed assay. The dark chocolate matrix produced a slightly higher background but still maintained an adequate dynamic range. The ELISA was highly specific except for considerable cross-reactivity to walnut. The performance of the developed assay for detection of pecan in processed (incurred) ice cream and sugar cookies was evaluated. Excellent recovery of pecan from manufactured vanilla ice cream (103% ± 4.28%) and sugar cookie (87.0% ± 5.45%)occurred. The developed ELISA demonstrates high specificity towards both roasted and raw pecans and thus is a potential method for food manufacturers and regulatory agencies to detect pecan residues in processed foods and facilitate the validation of allergen control programs for pecan.
Advisor: Joseph Baumert