The effect of corn starches (natural, pregelatinized, and cross-linked) in four levels on quality of low-protein biscuit was evaluated. First, the microscopic structure, thermal properties, and low-branched chains content of them were evaluated. Water absorption capacity (WAC) and gelatinization properties of combined starches and physicochemical properties of products were assessed. Cross-linked starch had the highest glass transition temperature (T g ). The maximum and minimum WAC was observed in samples containing 100% pregelatinized and 100% cross-linked starches,respectively. An increase in the amount of pregelatinized starch was accompanied by a decrease in the maximum viscosity and gelatinization temperature. Pregelatinized starch improved sensory and textural characteristics of samples, while cross-linked starch affected baking properties of the product. The best sample containing 30% of pregelatinized and 70% cross-linked starch with 1.27 g protein and 12 mg phenylalanine in 100 g biscuit is introduced as the low protein and safe product for Phenylketonuria. K E Y W O R D Sbiscuits, modified corn starch, phenylketonuria, physicochemical properties How to cite this article: Azaripour A, Abbasi H. Effect of type and amount of modified corn starches on qualitative properties of low-protein biscuits for phenylketonuria. Food