Abstract: In a method for measuring protein content of whole grain kernels with a near infrared spectrophotometer, reflectance measurements are made at wavelengths shorter than 1600 nanometers. The wavelengths are selected to correspond with absorbance bands of the constituents of the sample. The measurements are encoded into absorbance data and are normalized by subtracting the absorbance value at a first wavelength and then dividing the resulting data by the value at a second wavelength. In accordance with one embodiment, the normalized data is substituted in a formula having coefficients determined by regression from samples having known percentages of protein in the sample to yield the percentage of protein in the unknown sample. In accordance with a second embodiment, the second differential of the absorbance data is determined and the resulting differential values are inserted in the formula having coefficients obtained from the known samples to yield the percentage or protein in the unknown sample.

Abstract: In a spectrophotometric instrument, a system is provided to correct for distortion caused by rapid scanning of the spectrum. In the instrument, photodetectors detect light energy which is scanned through a spectrum at a rapid rate. An amplifier amplifies the output signal generated by the photodetectors. The output signal of the amplifier is sampled at increments and the samples are converted to digital values. A first derivative is determined from the digital values by subtracting from each value the value from the preceding increment. The first derivative values are multiplied times a constant selected to correct for the distortion and the resulting product values are added to the amplitude digital values to provide a set of corrected values representing the intensity detected by the photodetectors.