Celiac disease or gluten-sensitive enteropathy is an autoimmune disease that creates a smooth surface in the small intestine and restricts the consumption of grain products. Therefore, this study examines the replacement of flaxseed powder and inulin in gluten-free biscuits and the optimization of the formulation of this type of biscuit. In this study, the effect of replacing inulin (0–20%) and flaxseed powder (0–70%) with gluten-free rice flour in biscuits was investigated, and the textural, physicochemical, and sensory properties of biscuits were evaluated. The effect of two components of inulin and flaxseed powder on the dough properties showed that increasing the amount of inulin caused an increase in hardness, gumminess, springiness, adhesiveness, and reduced cohesiveness in the dough while increasing the amount of flaxseed powder replacement caused an increase in springiness and a decrease in hardness, cohesiveness, gumminess, and adhesiveness. Also, increasing the amount of rice flour compared to inulin caused an increase in ash, protein, moisture, and water activity. In addition, the replacement of flaxseed powder and inulin in biscuits caused an increase and a decrease in the hardness and a-value of biscuits, respectively. Sensory evaluation results of biscuits showed that high levels of flaxseed powder and inulin had an acceptable total acceptance score. According to the results, the addition of flaxseed powder increased the protein, fiber, ash, acidity, antioxidant properties, and calories and caused a decrease in pH and L-value in gluten-free biscuits. Adding inulin increased fiber and decreased water activity, moisture, and calorie. In general, according to the results, the sample containing 2% inulin, 68% flaxseed powder, and 30% rice flour (with a desirability of 0.92) was suggested as the optimal sample.
