Influence of hydroxypropylmethylcellulose (HPMC), xanthan gum and their combination on loaf specific volume, crumb hardness and crumb grain characteristics of gluten-free breads based on rice, maize, teff and buckwheat

Currently, the only effective treatment for coeliac disease is the complete avoidance of gluten, a protein found in wheat, rye and barley. The production of high-quality leavened baked goods made from ingredients other than wheat flour represents a major technological challenge, due to the absence of the visco-elastic gluten compound. To tackle these problems, hydrocolloids such as xanthan gum and hydroxypropylmethylcellulose (HPMC) are often incorporated into gluten-free formulations. This study used systematic baking trials based on a central composite design to investigate the influence of these two gums and their combination on gluten-free model systems. It was found that the effect of the hydrocolloids on the gluten-free model systems of this study varied according to the raw materials used. HPMC had a positive linear effect on volume of teff and maize breads and a negative linear effect on this parameter in rice breads, while the volume of buckwheat bread did not change. Xanthan addition had a negative linear effect on loaf volume of all breads. HPMC addition reduced crumb hardness of teff, buckwheat, maize and rice bread. Xanthan increased the crumb hardness of teff and buckwheat breads, while rice breadcrumb remained uninfluenced. Crumb hardness values of maize breads were reduced by xanthan addition. Also crumb grain characteristics such as area of cells and wall thickness was influenced by the hydrocolloids. Optimisation trials were carried out in order to determine optimal water and hydrocolloid addition levels. (c) 2012 Elsevier Ltd. All rights reserved.