What's the Best Way to Measure Gluten in Gluten-Free Foods?

Celiac.com 10/16/2017 - In Europe many commercially available, nominally gluten-free foods use purified wheat starch as a base, but what's the best way to way to measure the gluten content of gluten-free foods, particularly those based on purified wheat starch?

Currently, the only test for gluten quantitation certified by the Food and Agriculture Organization of the United Nations (FAO) is based on the R5 monoclonal antibody (MAB) that recognizes gliadin, but not glutenin.

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A team of researchers recently set out to determine the best way to measure the gluten content of nominally gluten-free foods, particularly those based on purified wheat starch. The research team included HJ Ellis, U Selvarajah and PJ Ciclitira. They are affiliated with the Department of Gastroenterology, Division of Diabetes and Nutritional Sciences at Kings College London, St Thomas Hospital in London.

Celiac disease is treated with a strict Gluten-Free Diet (GFD). Gluten is comprised of gliadin, Low (LMWG) and High (HMWG). To estimate gluten content of gluten-free foods, the R5 works by multiplying the R5 gliadin value by two to yield a gluten value.

The research team raised a panel of monoclonal antibodies to celiac disease toxic motifs. They then assessed the gluten content of three wheat starches A, B, & C that are supplied as standards for the Transia gluten quantitation kit, which is based on a MAB to omega-gliadin. They used separate ELISAs to measure gliadin, Low (LMWG) and High Molecular Weight (HMWG) glutenins.

They found that the gliadin levels in all three starches were always higher, as measured by one of the antibodies, than the levels measured with the other, and that the ratio between measurements made by the 2 MABs varied from 3.1 to 7.0 fold. The team noted significant differences in glutenin to gliadin ratios for different wheat starches.

Based on their results, the team suggests that the best way to measure the gluten content of nominally gluten-free foods, especially those containing purified wheat starch, is to first measure gliadin and glutenin, and to then add the values together.

This is because measurement of gliadin alone, followed by multiplication by two to yield a gluten content, appears to be inadequate for measuring total gluten in processed foods.

Source:

• Int J Hepatol Gastroenterol. 2017;3(1): 046-049.