Surface-associated proteins of wheat starch granules: suitability of wheat starch for celiac patients

Wheat starch is used to make baked products for celiac patients in several European countries but is avoided in the United States because of uncertainty about the amounts of associated grain storage (gluten) proteins. People with celiac disease (CD) must avoid wheat, rye, and barley proteins and products that contain them. These proteins are capable of initiating damage to the absorptive lining of the small intestine in CD patients, apparently as a consequence of undesirable interactions with the innate and adaptive immune systems. In this study, starch surface-associated proteins were extracted from four commercial wheat starches, fractionated by high-performance liquid chromatography and gel electrophoresis, and identified by tandem mass spectrometry analysis. More than 150 proteins were identified, many of which (for example, histones, purothionins, and glutenins) had not been recognized previously as starch-associated. The commercial starches were analyzed by the R-5 enzyme-linked immunosorbent assay method to estimate the amount of harmful gluten protein present. One of these starches had a low gluten content of 7 ppm and actually fell within the range proposed as a new Codex Alimentarius Standard for naturally gluten-free foods (maximum 20 ppm). This low level of gluten indicates that the starch should be especially suitable for use by celiac patients, although wheat starches with levels up to 100 ppm are deemed safe in the proposed Codex standards.