Study Points Toward Better Gluten-free Bread

Celiac.com 05/15/2009 - Certain proteins found in the gluten of wheat, rye and barley trigger adverse responses in people with gluten intolerance and celiac disease. This happens when the offending gluten proteins encounter the immune systems of susceptible individuals, triggering a CD4+ T-cell mediated immune response, together with inflammation of the small intestine. However, a number of gluten proteins contain no T-cell stimulatory epitopes, and so trigger no such adverse immune response. So, not all gluten is equally offensive to celiacs, and some may be both well tolerated and useful for making better bread.

Gluten proteins are found in multiple gene sites on chromosomes 1 and 6 of the three different genomes of hexaploid bread wheat (Triticum aestivum) (AABBDD).

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Gluten is the stuff that makes bread delightfully chewy, among other desirable properties, so being able to successfully incorporate non-offending gluten into bread recipes might yield better breads that are safe for consumption by folks with celiac disease. Obviously, being able to produce high-quality, celiac-safe bread on a commercial scale would be of tremendous benefit for both producers and consumers. Currently, most gluten-free bread contains no gluten, as it has been difficult or impractical to separate the offending proteins from the non-offending proteins.

Recently, a team of researchers based in the Netherlands attempted to  remove celiac disease-related protein from Chinese Spring wheat while maintaining the beneficial bread-baking properties.

The team was made up of Hetty C. van den Broeck, Teun W. J. M. van Herpen, Cees Schuit, Elma M. J. Salentijn, Liesbeth Dekking, Dirk Bosch, Rob J. Hamer, Marinus J. M. Smulders, Ludovicus J. W. J. Gilissen and Ingrid M. van der Meer.

The team used a set of deletion lines of Triticum aestivum cv. Chinese Spring to assess the results of removing individual gluten sites on both the level of the T-cell stimulatory epitope in the gluten proteome and the favorable qualities of the flour.

To measure the reduction of T-cell stimulatory epitopes, the team used monoclonal antibodies that recognize T-cell epitopes contained in gluten proteins. They then clinically tested the deletion lines for their dough mixing properties and dough composition.

The team's attempts to remove the alpha-gliadin site from the short arm of chromosome 6 of the D-genome (6DS) yielded in a favorable decrease in the presence of T-cell stimulatory epitopes, but also yielded a significantly loss of favorable baking properties.

However, by deleting the omega-gliadin, gamma-gliadin, and LMW-GS locations from the short arm of chromosome 1 of the D-genome (1DS), researchers were able to strip offending T-cell stimulatory epitopes from the proteome while maintaining technological properties.

The team concludes that their data hold important implications for lowering the quantity of T-cell stimulatory epitopes in wheat, and promoting the creation of celiac-safe wheat varieties that will potentially yield breads of higher quality than currently available.

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