The effect of extrusion operating conditions on main quality properties of glutenfree expanded snack-type products, developed from rice grits and bandinha flour formulations, was studied. The protein content in the extrudate varied from 9.44 to 14.74 g/100 g for formulations containing 13 and 47% bandinha flour, respectively, processed at 85C and 15% feed moisture. Apparent density and the radial expansion index of the extrudate were significantly (P < 0.05) affected by bean flour content, moisture content, temperature and the interaction between moisture content × temperature. The most suitable extrusion conditions were 30 g/ 100 g bean flour content, 14 g/100 g moisture content and 80C die temperature, which resulted in a product with a high radial expansion index and crude protein of 9.5 and 13 g/100 g, respectively, and a low apparent density of 0.20 g/cm 3 .
PRACTICAL APPLICATIONSThere is a dynamic growth trends taking place in the gluten-free market due to its relationship to celiac disease, wheat allergy, gluten intolerance and gluten sensitivity. To date, most gluten-free products in the market are in the form of pasta and bakery products. However, there is an open niche for gluten-free foods in the form of expanded snack-type products. The flours of underutilized broken rice and beans ("bandinha"), processed under the selected range of extrusion conditions in this study, have great potential for the development of value-added, protein-rich, gluten-free foods in the form of expanded, low-density, snack-type products. The factorial design used to determine the relationship between the independent and the response variables aided to determine the most suitable processing conditions to generate a quality end product.