Abstract: Objective: To separate and purify amylose and amylopectin from cassava starch and to establish a dual-wavelength spectrophotometric method for determining their contents. Methods: The amylose and amylopectin in cassava starch were separated by n-butanol crystallization method. The purity of amylose and amylopectin was characterized by blue value of starch-iodine complex. According to the principle of dual-wavelength spectrophotometry method, the contents of amylose and amylopectin in cassava starch were determined at the selected wavelengths of 624 nm and 538 nm with respective reference wavelengths of 440 nm and 750 nm. Results: The blue values of purified amylose and amylopectin were 0.979 and 0.144, respectively, which were in the distribution range of corresponding standard samples. A high purity of cassava amylose and amylopectin was achieved. An excellent linear relationship between starch-iodine complex and absorbance was achieved in the range of 0－80 mg/L (r＝0.9992) for amylose and 0－220 mg/L (r＝0.9995) for amylopectin. Conclusion: n-butanol crystallization method amylose and amylopectin from cassava starch. The developed dual-wavelength spectrophotometry method is convenient, accurate and suitable for determining the contents of amylose and amylopectin in cassava starch simultaneously.

Key words: amylose, amylopectin, separation, n-butanol crystallization, dual-wavelength spectrophotometry