Cereal Chem 72:182-187  |  VIEW ARTICLE

Apparent Amylose Content of Milled Rice by Near-Infrared Reflectance Spectrophotometry.

S. R. Delwiche, M. M. Bean, R. E. Miller, B. D. Webb, and P. C. Williams. Copyright 1995 by the American Association of Cereal Chemists, Inc. 

Amylose content is considered to be the most important factor influencing cooking and processing characteristics of rice. Traditional methods for measurement entail titrimetric, amperometric, or colorimetric measurement of an iodine-binding complex of solubilized starch, but these methods are time- consuming and prone to random error. A method for determining apparent amylose content (AAC), based on the near-infrared (NIR) reflectance spectrum (1,100-2,498 nm) of ground milled rice, was developed on a diverse population of 50 commercial rice varieties or experimental lines grown in the five major rice- producing states of the United States. Three laboratories possessing NIR spectrophotometers participated in a cooperative study. Each laboratory ground, scanned, and devel oped AAC models by partial least squares analysis, using common sets of samples for calibration (n = 150) and validation (n = 97). Validation set statistics typically indicated r2 = 0.95 and standard error = 1.0% AAC for models consisting of 16-18 factors. Within-laboratory repeatability error of the NIR method was comparable to the reference colorimetric method. Between-laboratory reproducibility error (0.5% AAC) indicated that the NIR models were consistent across laboratories. Such accuracies are considered sufficient for selection in rice breeding programs.