EFFECT OF CEREAL PRODUCT RESIDUAL MOISTURE-CONTENT ON TOTAL DIETARY FIBER DETERMINED BY NEAR-INFRARED REFLECTANCE SPECTROSCOPY

Published studies on the applications of near-infrared reflectance spe ctroscopy (NIRS) to the analysis of fiber in forages, feeds, grains, a nd cereal products indicate the presence of O-H absorbance, due to sam ple moisture content, in the calibration models. The objective of this study was to determine the extent to which residual moisture in sampl es interferes with the ability of NIRS to predict total dietary fiber (TDF) in cereal products and grains. Milled cereal products and grains were stored in 20%, 60%, and 80% experimental relative humidity (rh) environments and a vacuum oven. Samples (N = 143) were analyzed for mo isture and predicted for TDF. Results showed significant differences b etween laboratory reference TDF and predicted TDF for samples that wer e either very low or very high in moisture. Cereal products and grain samples stored under ambient conditions (N = 90) were combined with se lected samples stared under different rh environments (N = 53) to deve lop a new calibration using partial least squares regression. The stan dard error of cross validation and multiple coefficient of determinati on (R(2)) were 1.85% and 0.98, respectively. The model was validated w ith an independent set of cereal products (N = 29) stored under ambien t and rh environments. Samples stored under ambient and rh environment s were predicted with standard errors of performance of 1.70% and 1.86 %, respectively. The study shows that NIRS can be used to predict TDF in cereal products and grains with a wide range of residual moistures when calibrations include the range of residual moisture expected.