Lysine Estimation in Cereals by Near‐Infrared Reflectance¹

Abstract

The determination of lysine in cereals has been limited by methods which are slow and relatively expensive. Experimental data obtained with a standard near‐infrared‐ reflectance (NIR) instrument — commercially available to determine protein, moisture, lipids, and other constituents of cereals and oil seeds — were highly correlated (r = 0.98) with lysine in some 77 samples of hard red (spring and winter) wheats ( Triticum aestivum L.). Standard error (Sy•x) for the test was ±0.049 mg lysine/ 100 g protein. The method is rapid (1 min), relatively accurate, involves little sample preparation, and provides direct readout of lysine. The test is non‐destructive and, therefore, the sample can be used for other quality tests. Minimum sample required is approximately 2 g and optimum is 6 to 8 g. Care in sample selection, preparation (grinding and filling the sample cell), and monitoring with a reference method is necessary for consistent meaningful results.