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

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.