Near-Infrared Reflectance Measurement of Total Sugar Content of Breakfast Cereals

Abstract

Two different computerized scanning near-infrared (NIR) reflectance instruments were used to determine the total sugar content of 84 samples of ready-to-eat breakfast cereals. One of the instruments was commercially built, the Neotec 6350, and the other was built in the Instrumentation Research Laboratory, HSI, ARS, USDA. The total sugar content of the cereals, as determined by gas-liquid chromatography (GLC), ranged from 0 to 54%. The samples were divided into two sets, one used for calibration of both NIR instruments and the other used for prediction. Various mathematical treatments of the spectral reflectance data were evaluated for optimal prediction of sugar content, and best prediction by both instruments was obtained by a two-term regression equation using ratios of first derivatives of log 1/ R. The correlation between the NIR measurement and the GLC analysis was the same for both instruments. The standard errors of prediction of 2.8% and 2.7% total sugar are only slightly larger than the errors associated with the GLC method with which they are compared. Two different types of spectra were observed in the cereal samples. One was identified as characteristic of crystalline sugar, and the other characteristic of amorphous sugar.