PREDICTION OF TOTAL DIETARY FIBER BY NEAR-INFRARED REFLECTANCE SPECTROSCOPY IN HIGH-FAT-CONTAINING AND HIGH-SUGAR-CONTAINING CEREAL PRODUCTS

The near-infrared (NIR) spectral properties of cereal products contain ing high fat or high sugar can differ substantially from the spectral properties of other cereal products. An existing NIR model, using prep rocessed reflectance spectra and partial least-squares analysis, for t he prediction of total dietary fiber in cereal products was expanded t o two new models called (1) the ''fat-expanded'' model and (2) the ''f at- and sugar-expanded'' model. The fat-expanded model enlarges the ex isting model with high-fat-content products as calibration samples, an d the ''fat- and sugar-expanded'' model also includes products with hi gh sugar and high crystalline sugar content. The dry milled cereal and grain products were analyzed in the laboratory according to AOAC meth od 991.43 for the determination of total dietary fiber, and NIR reflec tance spectra were collected with a scanning monochromator. Data analy sis and selection of representative high-fat and high-sugar samples we re performed with a commercial analysis program. The two expanded mode ls had standard errors of cross-validation and R-2 similar to those of the existing model, with acceptable standard error of performance and r(2) when tested with independent validation samples. The existing mo del was, thus, expanded to include high-fat, high-sugar, and high crys talline sugar cereal products while maintaining prediction accuracy.