Comparison of gluten recovery in gluten-incurred buckwheat flour using different commercial test kits

Abstract

Recovery of gluten in buckwheat flour was evaluated as part of an effort to produce wheat-contaminated buckwheat flours that could be used as reference materials (RMs) for testing the presence of gluten in buckwheat. RMs of buckwheat containing 0, 20, 100 and 1000 ppm gluten were created and tested by ELISA. The Gluten-Check kit detected gluten accurately at all levels; RIDASCREEN and Biokits tests were accurate at 20 and 100 ppm levels, but at 1000 ppm both suffered from extraction saturation effect; Veratox kit read 60% higher for the 20 ppm RM (i.e., 31.9 ppm), but close to the target at 100 ppm RM; Veratox R5 kit showed low accuracy with around 30% recovery at 20 and 100 ppm and some 60% at 1000 ppm level. Overall, the results showed variations in recovery among different test kits which could have important implications in the accurate detection of gluten in buckwheat.

Development of an Incurred Cornbread Model for Gluten Detection by Immunoassays

“…21 A decrease in gluten recovery by the R-Biopharm and BioKits ELISA kits at higher levels of gluten (1000 ppm compared to 20 and 100 ppm) in buckwheat flour was attributed to the extraction saturation effect. 21 Effect of the Baking Time on Gluten Detection. The temperature causes various physical and chemical modifications in proteins, which may affect the ELISA quantification by reducing extraction efficiency and/or changing the antigen− antibody interaction.…”

“…The poor fit may be due to the lack of enough data points because only three incurred levels were selected for longer baking times. A concentration-dependent variation in gluten quantitation by ELISA has been observed using gluten-spiked oat flour or buckwheat flour . A decrease in gluten recovery by the R-Biopharm and BioKits ELISA kits at higher levels of gluten (1000 ppm compared to 20 and 100 ppm) in buckwheat flour was attributed to the extraction saturation effect …”

Gluten Analysis of Wheat Starches with Seven Commercial ELISA Test Kits—Up to Six Different Values

“…In the absence of an independent reference method and a certified reference material, the performance of different test kits is typically evaluated after the analysis of spiked or incurred materials with defined gliadin or gluten contents. These may be prepared by adding the Prolamin Working Group (PWG)-gliadin reference material (van Eckert et al 2006) into a model cookie recipe based on gluten-free corn flour (Bugyi et al 2013) or amaranth flour (Török et al 2015); by mixing gluten or wheat flour into corn flour (Sharma 2012) or a cornbread recipe (Sharma et al 2013); by blending wheat flour and buckwheat flour (Alvarez and Boye 2014) or whole wheat, whole rye, or barley flour and rice flour (Bruins Slot et al 2015a); or by spiking sausage meat, pastries, and infant semolina with wheat flour, spelt whole flour, wheat whole grain flakes, or wheat semolina (Scharf et al 2013). After comparison of the values determined by different gluten test kits with the target values, gliadin or gluten recoveries may be calculated.…”