title: Fast and nondestructive determination of protein content in rapeseeds (Brassica napus L.) using Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS).
abstract: BACKGROUND
  Fast and non-destructive determination of rapeseed protein content carries significant implications in rapeseed production. This study presented the first attempt of using Fourier transform mid-infrared photoacoustic spectroscopy (FTIR-PAS) to quantify protein content of rapeseed. The full-spectrum model was first built using partial least squares (PLS). Interval selection methods including interval partial least squares (iPLS), synergy interval partial least squares (siPLS), backward elimination interval partial least squares (biPLS) and dynamic backward elimination interval partial least squares (dyn-biPLS) were then employed to select the relevant band or band combination for PLS modeling.
  
  
  RESULTS
  The full-spectrum PLS model achieved an ratio of prediction to deviation (RPD) of 2.047. In comparison, all interval selection methods produced better results than full-spectrum modeling. siPLS achieved the best predictive accuracy with an RPD of 3.215 when the spectrum was sectioned into 25 intervals, and two intervals (1198-1335 and 1614-1753 cm(-1) ) were selected. iPLS excelled biPLS and dyn-biPLS, and dyn-biPLS performed slightly better than biPLS.
  
  
  CONCLUSIONS
  FTIR-PAS was verified as a promising analytical tool to quantify rapeseed protein content. Interval selection could extract the relevant individual band or synergy band associated with the sample constituent of interest, and then improve the prediction accuracy of the full-spectrum model.
authors.affiliation: Institute of Soil Science, National Key Laboratory of Soil and Sustainable Agriculture Chinese Academy of Sciences, Nanjing, 21008, China.
authors.forename: Yuzhen
authors.initials: Y
authors.lastname: Lu
authors.forename: Changwen
authors.initials: C
authors.lastname: Du
authors.forename: Changbing
authors.initials: C
authors.lastname: Yu
authors.forename: Jianmin
authors.initials: J
authors.lastname: Zhou
mesh_terms: D029688:Brassica napus / Q000737:chemistry*; D029741:Brassica rapa / Q000737:chemistry*; D004032:Diet; D004044:Dietary Proteins / Q000032:analysis*; D006801:Humans; D016018:Least-Squares Analysis; D061088:Photoacoustic Techniques / Q000379:methods*; D015203:Reproducibility of Results; D012639:Seeds / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D004044:Dietary Proteins
keywords: interval selection; partial least squares (PLS); photoacoustic spectroscopy; protein content; quantification; rapeseed