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The purpose of this research is to investigate the effect of the changes in the starch slurry with the concentration of 30, 50 and 70% of dry substance of pregelatinized acorn starch using a single drum dryer at a drum temperature of 120°C and a speed of 20 rpm which is called PGS30, PGS50 and PGS70 in order on physical and chemical properties including viscosity, hydration, freezing and melting stability, degree of gelatinization, morphology and FTIR .The rheological properties were evaluated using a rapid viscosity analyzer as a function of temperature. Pregelatinized starches showed viscosity at 25°C in cold water, but native acorn starch did not show viscosity at room temperature. Native acorn starch gradually started to absorb water as the temperature increased. So that the highest viscosity (peak) was created by native acorn starch, PGS30, PGS50 and PGS70 respectively. Native acorn starch granules have a smooth surface and non -homogeneous shape (mostly oval and spherical) and also have surface cavities and wrinkles. The morphology of pregelatinized starches changed significantly so that the granules of PGS50 and PGS70 samples are continuous and porous with a honeycomb -like structure. And there was no significant change in freezing - thaw stability compared to native acorn starch (p<0.05). The spectroscopic evaluation of native acorn starch was consistent with PGS samples up to the spectral range of 13343 cm. But in the PGS70 and PGS50 samples, several spectral intervals occurred between 3747 and 3945, which indicates the complete gelatinization of these two samples. Pregelatinized starches also have more swelling power, water absorption and solubility than native acorn starch (p≥0.05). [ABSTRACT FROM AUTHOR]