Abstract:Dual-wavelength colorimetry was developed to determine amylose and amylopectin contents after the starch was isolated from potato. By staining with I2-KI solution, amylose displayed a blue color, amylopectin displays a violet color. Absorbancies at 535 and 570nm were used for amylose content measurement, absorbancies at 555 and 760 nm are used for amylopectin content measurement. The XIN DAPING potato starch (from Dingxi, Gansu province) contained 21.20 % of amylase and 78.80 % of amylopectin. The detection results can be affected by the sample dissolution and the reaction time of starch and I2-KI solution.
