Amylose/amylopectin simple determination in acid hydrolyzed tapioca starch

Abstract

Analysis of the shift of wavelength maximum using a rapid colorimetric method was used to determine the ratio of amylose:amylopectin (Am:Ap) in acid-hydrolyzed tapioca starch. The absorbance maximum of 600 nm (Am:Ap of tapioca starch ≈22:78) moved to shorter wavelengths (590, 585, 570, 560, and 534 nm) as the decrease of the Am:Ap ratio due to hydrolysis of shorter chains that are not be able to form a complex with iodine. The amount of amylopectin itself may be unaltered or slightly decreased but the decrease in amylose caused a decrease in Am:Ap ratio.