Soulef Benkadri

Incorporation of xanthan gum and locust bean gum in rice flour supplemented by chickpea flour was used to obtain a good quality of nutritionally enriched biscuit for celiac children. Response surface methodology (RSM) was applied to optimize the levels of xanthan and locust bean gum added to the composite gluten-free flour. Analysis was based on the rheological (hardness and viscoelastic) characteristics of the dough and specific volume, water activity, and hardness of the biscuit. The results revealed that the regression and variance analysis coefficients related to the rheological and physical properties of dough and biscuit under the influence of independent variables were sufficient for an adequate and well-fitted response surface model. Linear terms of variables significantly affect most of the dough and biscuit parameters, where the xanthan gum effect was found to be more pronounced than locust bean gum. Interaction terms showed a significant positive effect on the specific volume of the biscuits and a negative effect on the water activity. However, the interactive effect of gums did not significantly affect the rheological parameters of the dough. Optimized conditions were developed to maximize the specific volume of biscuit and minimize water activity and biscuit hardness, while keeping hardness and viscoelastic properties of the dough in range. Predicted responses were found satisfactory for both rheological and physical characteristics of dough and biscuit.

A gluten-free biscuit for celiac children based on composite rice–chickpea flour was developed. Xanthan gum was used to overcome the handling difficulties associated with the absence of gluten in the rice–chickpea flour. The effect of different levels of xanthan gum incorporation (0.5, 1, and 1.5% of flour) on the texture and rheological properties of the dough and on the texture, dimensions, moisture, water activity (a_w), and sensory acceptability of the biscuit was studied. The incorporation of xanthan gum into rice–chickpea flour significantly affected the textural and linear viscoelastic properties of the dough, as well as the texture, weight, moisture, a_w, and dimensions of the biscuits. Increasing the xanthan gum level increases the hardness and elasticity of the dough, and decreases its springiness, cohesiveness, and adhesiveness. The addition of xanthan gum resulted in a significant improvement in the thickness and specific volume of biscuits. Xanthan gum water holding capacity increases the moisture content and the a_w of the baked biscuits and reduces biscuit hardness. In terms of sensory acceptability, xanthan gum slightly reduces rice–chickpea flour biscuit acceptability, but the differences were not significant. Consequently, using xanthan gum to achieve the proper technological properties of dough required for the industrial production of gluten-free rice–chickpea flour biscuits is a viable alternative.