Nondestructive assessment of amino acid composition in rapeseed meal based on intact seeds by near-infrared reflectance spectroscopy

The ability of near-infrared spectroscopy (NIRS) was tested for estimating individual and total amino acid contents in rapeseed meal. Twelve different amino acids (aspartic acid, threonine, serine, glutamic acid, glycine, isoleucine, leucine, tyrosine, phenylalanine, lysine, histidine and arginine) in rapeseed meal could be predicted. The R2 ranged from 0.89 to 0.98, 1 − VR (1 minus the ratio of unexplained variance to total variance) ranged from 0.86 to 0.97 and the ratio of sample standard deviation (SD) to the standard error of cross-validation (SECV) ranged from 2.69 to 5.90. The equations for alanine showed better agreement between reference value and spectra (R2 = 0.84, 1 − VR = 0.82 and SD/SECV = 2.15). The calibration model for proline (R2 = 0.81 and 1 − VR = 0.78), methionine (R2 = 0.80 and 1 − VR = 0.78), cysteine (R2 = 0.76 and 1 − VR = 0.74), and valine (R2= 0.62 and 1 − VR = 0.58) however explained less variation. The NIRS prediction equation for total amino acid also showed high coefficient of determination (R2 = 0.93) and SD/SECV (3.87), and low SECV (17.01 g/kg). Equations of 9 amino acids (aspartic acid, glutamic acid, glycine, alanine, valine, leucine, lysine, histidine and arginine) were developed for relative contents of total amino acid and deemed useful for prediction with R2 values from 0.80 to 0.95, 1 − VR from 0.70 to 0.95 and SD/SECV from 1.83 to 3.95 and reasonably low SECV values. These results demonstrated that NIRS is a reliable tool for nondestructive assessment of variation in amino acid contents, increasing the efficiency of breeding and accelerating the selection process in rapeseed.