Impact of the preparation procedure on gliadin, glutenin and gluten contents of wheat starches determined by RP-HPLC and ELISA

Celiac disease patients rely on safe gluten-free products, and the use of purified wheat starch (WSt) as part of the diet is usually well tolerated. However, uncertainties about residual gluten amounts in WSt remain, because ELISAs target the alcohol-soluble prolamin (gliadin) fraction of gluten, but hardly detect the alcohol-insoluble glutelin (glutenin) fraction. Therefore, gliadin, glutenin and gluten contents of WSt prepared from doughs on a laboratory scale were monitored by RP-HPLC. WSt washed with water from optimally or overmixed doughs had the lowest gluten contents. Gliadins were removed more extensively than glutenins during consecutive washing steps, so that gluten contents analyzed by ELISA were lower than those by RP-HPLC in 17 out of 24 WSt samples. The inability to detect glutelins by ELISA may thus lead to an underestimation of gluten contents in WSt. These findings highlight the need for improved analytical methods capable of detecting both prolamins and glutelins in processed food samples.