Direct analysis of the main chemical constituents in Chenopodium quinoa grain using Fourier transform near-infrared spectroscopy

•The quinoa is an indigenous crop from Andes with high protein content.•The ability of NIRS to estimate the composition of quinoa grain was evaluated directly.•Excellent prediction results were obtained using NIR and chemometrics without sample preparation.

Interest in the research and development of quinoa, an indigenous Andean crop, has increased in the last 15 years, mainly because of its nutritional value and high seed yield. Near-infrared spectroscopy (NIRS) is a rapid non-destructive technique, which is useful for studying the chemical properties of these crops. Considering these advantages, the objective of this research is to develop NIRS calibrations suitable for the routine determination of dietary constituents in 78 varieties of quinoa using partial least squares (PLS). For recording NIR a sample spinner accessory of diffuse reflectance was applied directly on the quinoa samples without treatment was used. The PLS models developed for the quantification of moisture, ash, lipid, protein and carbohydrate content showed that the proposed methodology produced suitable results, with the graph of the real and predicted concentrations having a coefficient of determination (R2) > 0.737 and RMSEP < 4.36%. This results show that NIRS with diffuse reflectance accessory provides an alternative for the determination of chemical compounds of quinoa, faster, at lower cost and no sample preparation.