Baking gluten-free breads for the ever-growing coeliac population may be possible using brown rice and buckwheat flours and adding the transglutaminase enzyme, according to results of a European project.
While use of the TGase enzyme is not new in for gluten-free products, the study is the first to formulate bread without the addition of hydrocolloids, according to results published in the Journal of Cereal Science.
"The replacement of the gluten network in the development of gluten-free cereal products is a challenging task for the cereal technologist," wrote lead author Stefano Renzetti from the National University of Ireland, Cork.
"The aim of the present study was to investigate the effectiveness of TGase application in improving the baking performances of gluten-free flours without addition of any hydrocolloids, and thus get a better insight on the extent of cereal proteins modifications and network forming promotion for bread making."
According to market analyst Mintel the overall 'free-from' market has already enjoyed sales growth of over 300 per cent since 2000. The growing demand has opened up a new lucrative sector that many food makers are keen to exploit.
The free-from market was worth €90 million ($123 million) in 2005, and Mintel said that the gluten and wheat-free sector has benefited in particular from the nation's increasing interest in healthy eating. Sales of products such as wheat-free breads and cakes have grown by almost 120 per cent over the last three years alone, to reach €48 million ($65 million).
However, while the market for such products is booming, according to the experts at IFT, researchers have yet to fully solve their greatest challenge - making products taste good.
Replacement of wheat in baked goods, like bread and cookies, poses technical problems since gluten impacts significantly on the texture and taste of the final product.
The new study tested the effectiveness of TGase (Ajinomoto), an enzyme that cross-links protein, to form networks in flours from six different gluten-free cereals, including brown rice, buckwheat, corn, oat, sorghum and teff.
The researchers, funded by the European Commission's Healthgrain project, found that batters and breads made with buckwheat and brown rice and using the enzyme at a concentration of 10 units per gram "showed improved baking characteristics as well as overall macroscopic appearance."
Moreover, 3-D imaging showed that protein complexes were formed by the addition of TGase.
On the other hand, corn flour products were not satisfactory, highlighting the importance of the protein source for optimal results.
"The results of the present study show that the functionality of gluten-free flours in terms of bread-making performances can be successfully improved by the action of
TGase," wrote the researchers.
"Buckwheat and brown rice flours were the optimal substrates for TGase application among the investigated flours," they added.
Coeliac disease is caused by an intolerance to gluten - the protein found in wheat, rye and barley - and currently affects an average of one in 300 people in Europe. In Germany the figure is higher at one in 200, while the UK reports a figure of one in 100.
Source: Journal of Cereal Science
July 2008, Volume 48, Issue 1, Pages 33-45
Microstructure, fundamental rheology and baking characteristics of batters and breads from different gluten-free flours treated with a microbial transglutaminase
Authors: S. Renzetti, F. Dal Bello, E.K. Arendt