Cereal Chem 68:545-548   |  VIEW ARTICLE

Comparison of Two Models to Predict Amylose Concentration in Rice Flours as Determined by Spectrophotometric Assay.

P. S. Landers, E. E. Gbur, and R. N. Sharp. Copyright 1991 by the American Association of Cereal Chemists, Inc. 

A spectrophotometric assay was used to test two models for predicting amylose in 16 solutions containing known concentrations of amylose and amylopectin and in 10 rice flours of unknown composition. The simple linear regression model based on an amylose-only standard curve overpredicted amylose in all solutions (relative bias of 7-329%). The model used for simultaneous estimation of amylose and amylopectin was more accurate with some slight overprediction or underprediction of amylose (less than 6%). The amylose-only method predicted amylose content to be 7.4% for waxy flour and 16.4-25.4% for nonwaxy varieties. Defatted flours were measured at 8.0% (waxy) and 18.4-29.6% (nonwaxy). Lower amylose content was measured by the simultaneous estimation method. Predictions for the flours were 0% (waxy) and 6.6-14.2% (nonwaxy). Defatted flours had 0% (waxy) and 9.8-22.0% (nonwaxy). This method resulted in greater accuracy, although use of laboratory time and resources was not changed.