title: Chemical characteristics and mineral composition of quinoa by near-infrared spectroscopy.
abstract: BACKGROUND
  Quinoa (Chenopodium quinoa Willd.) has been traditionally used as a foodstuff in the Andes and it has gained increasing interest in recent years owing to its high nutritional value. The potential of near-infrared spectroscopy (NIRS) for estimating chemical compounds in quinoa was studied because of the possibility of conducting direct measurement without prior sample treatment.
  
  
  RESULTS
  The use of NIRS technology with a remote reflectance fiber-optic probe for the analysis of major compounds and mineral composition of 48 quinoa samples was studied. The calibration of the NIRS instrument was conducted using modified partial least squares (MPLS) analysis. This allowed the determination of protein (16.0-20.2 g 100g⁻¹), crude fiber (1.8-3.1 g 100g⁻¹), fat (4.4-7.5 g 100g⁻¹), calcium (298.8-1164.5 mg kg⁻¹), iron (0-948.5 mg kg⁻¹) and phosphorus (2735.0-4543.3 mg kg⁻¹). The correlation coefficients (RSQ) were 0.83 for protein, 0.73 for crude fiber, 0.93 for fat; 0.60 for calcium; 0.76 for iron and 0.75 for phosphorus. The robustness of the equations obtained was verified by external validation on unknown quinoa samples.
  
  
  CONCLUSIONS
  NIRS with fiber-optic probe provides an alternative for the determination of chemical compounds of quinoa, faster and at lower cost, with results comparable with chemical methods.
authors.affiliation: Department of Analytical Chemistry, Nutrition and Food Science, Faculty of Chemistry, University of Salamanca, 37008, Salamanca, Spain.
authors.forename: M Inmaculada
authors.initials: MI
authors.lastname: González Martín
authors.forename: Guillermo
authors.initials: G
authors.lastname: Wells Moncada
authors.forename: Susana
authors.initials: S
authors.lastname: Fischer
authors.forename: Olga
authors.initials: O
authors.lastname: Escuredo
mesh_terms: D002136:Calcium, Dietary / Q000032:analysis*; D002138:Calibration; D055598:Chemical Phenomena; D027465:Chenopodium quinoa / Q000737:chemistry*; D002677:Chile; D004041:Dietary Fats / Q000032:analysis; D004043:Dietary Fiber / Q000032:analysis; D004044:Dietary Proteins / Q000032:analysis; D005336:Fiber Optic Technology; D005513:Food Inspection / Q000379:methods*; D063427:Food Quality; D006801:Humans; D019266:Iron, Dietary / Q000032:analysis*; D016018:Least-Squares Analysis; D009753:Nutritive Value; D016226:Phosphorus, Dietary / Q000032:analysis*; D010940:Plant Proteins / Q000032:analysis; D012639:Seeds / Q000737:chemistry*; D013045:Species Specificity; D019265:Spectroscopy, Near-Infrared
chemical_list: D002136:Calcium, Dietary; D004041:Dietary Fats; D004043:Dietary Fiber; D004044:Dietary Proteins; D019266:Iron, Dietary; D016226:Phosphorus, Dietary; D010940:Plant Proteins
keywords: Chenopodium quinoa; cross-validation; major compounds; minerals; near-infrared spectroscopy