Rice and corn flours are appropriate alternatives for developing gluten free products and modification of some of their properties such as water absorption index of flour due to extrusion process could be effective for improvement of gluten-free products quality. In this research, addition effect of extruded flour in 110 °C with 18% feed moisture, in four levels ( 0, 10, 20 and 30%) and hydrocolloids of xanthan and hydroxypropylmethylcellulose in two levels ( 0.5 and 1%) of each were studied in gluten-free bread formulation. The results were proved significant effect of extruded flour and hydrocolloids addition on evaluated characteristics so that specific volume and porosity were promoted with increasing level of extruded flour till 10%, but higher levels were caused reduction of these properties. Also, increasing of extruded flour  level was decreased crust L* and hydroxypropylmethylcellulose had more effect on crumb hardness reduction of gluten free bread in compared to xanthan. Finally with regard to features such as specific volume, porosity, softness, color and scores of sensorial test, gluten free bread formulation including 10% extruded flour and 1% HPMC was determined as appropriate formulation which had specific volume of 3.01 cm³/g, porosity of 65% and overall acceptance score of 4.1 in sensorial test.

 

Keywords: free-gluten flour, extrusion, rice, corn, xanthan

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