Simultaneous and Rapid Spectrophotometric Determination of Amylose,Amylopectin,and Total Starch in Wheat Grain

In order to determine amylose and amylopectin content rapidly and accurately and guide genetic improvement of wheat starch,different spectrophotometric methods for determining amylose,amylopectin and total starch content were compared among single,double and six wavelengths.In addition,the factors,such as pH value,affecting the measurement were optimized and discussed.Results showed that the iodine-binding capacity of wheat starch was quite different from that of potato displayed by the absorbance spectrum of complexes formed with iodine.Regression equations with high correlation coefficients were developed from different methods of single,double,and multi wavelengths,respectively.The methods with both double and six wavelengths were more suitable to determine amylose and amylopectin content simultaneously and rapidly than that with single wavelength because they excluded the interference of other biomoleculars existing in the reaction system efficiently.Furthermore,wheat amylose and amylopectin content determined by double wavelengths was more accurate and simple than by multi wavelengths.Optimized from this experiment,the amylose content was determined by 630 and 486 nm,and amylopectin by 550 and 743 nm,respectively.The pH value of the reaction system was around 3.5.