Determination of Amylose and Amylopectin Contents in Yam and Taros by Dual-Wavelength Spectrophotometry

Objective: The paper aims to establish a dual-wavelength spectrophotometry method for the determination of the content of amylose and amylopectin in yam and taros, and to provide basic data for variety selection, quality grading, product processing and standard formulation. Method: The spectrum of amylose and amylopectin were studied and the maximum absorption wavelength and reference wavelength were determined. The color conditions such as dispersant and acetic acid and measuring conditions were optimized. The absorbance values of the color complexes were determined. Result: The standard curve equation of amylose was y=0.0259x−0.0051, R²=0.9994, with the linear range of 0~33 μg/mL. The standard curve equation of amylopectin was y=0.0031x+0.0167, R²=0.9965, with the linear range of 0~111 μg/mL. The limits of detection and quantification of amylose were 0.093 μg/mL and 0.28 μg/mL respectively. The limits of detection and quantification of amylopectin were 0.079 μg/mL and 0.24 μg/mL, respectively. The recovery of amylose was 90.0%~100.0%. The recoveries of amylopectin were 88.0%~108.0%. Conclusion: The dual-wavelength spectrophotometry method was simple and feasible, accurate and reliable. It was suitable for the determination of amylose and amylopectin in yam and taros.