title: Univariate and multi-variate comparisons of protein and carbohydrate molecular structural conformations and their associations with nutritive factors in typical by-products.
abstract: BACKGROUND
  Little attention has been paid on the inherent molecular structural effects among agricultural by-products. In this study, soybean meal (SM), wheat bran (WB), corn distillers dried grains with soluble (DDGS), dry brewer's grain (DBG), wet brewer's grain (WBG), and apple pomace (AP), which are widely used in the animal industry were selected to explore protein and carbohydrate molecular structural conformations.
  
  
  RESULTS
  All the protein peak heights (including α-helix and β-sheet) and areas were exhibited highest values in SM and lowest in AP. The SM had the highest peak area intensity of cellulosic compounds (CELC), while the remaining varieties showed the lowest absorbance level. The TSCHO (sum of structural carbohydrate (SCHO) and CELC area exhibited variations among the samples. Multivariate comparisons showed AP had no molecular structural association with other by-products within the protein amide region. Protein amides I, II and (I+II) areas, α-helix, β-sheet and area ratio of protein amide and (TSCHO + TCHO) had strong relationships with CP, NDF, ADF, ADL, SCP, starch, PC, CA, CC and TDN contents.
  
  
  CONCLUSIONS
  Inherent molecular structures varied among the selected by-product types and they might be used as potential predictors of nutritive factors, especially for protein structural information. © 2016 Society of Chemical Industry.
authors.affiliation: College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China. hangshu.xin@neau.edu.cn.
authors.forename: Hangshu
authors.initials: H
authors.lastname: Xin
authors.affiliation: College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China.
authors.forename: Yongli
authors.initials: Y
authors.lastname: Qu
authors.affiliation: College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China.
authors.forename: Haonan
authors.initials: H
authors.lastname: Wu
authors.affiliation: Department of Animal and Poultry Science, College of Agricultural and Bioresources, University of Saskatchewan, Saskatoon, SK, Canada. peiqiang.yu@usask.ca.
authors.forename: Peiqiang
authors.initials: P
authors.lastname: Yu
authors.affiliation: College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China.
authors.forename: Yonggen
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D002236:Carbohydrate Conformation; D002241:Carbohydrates / Q000737:chemistry*; D002523:Edible Grain / Q000737:chemistry*; D027845:Malus / Q000737:chemistry*; D009753:Nutritive Value; D010940:Plant Proteins / Q000737:chemistry*; D011487:Protein Conformation; D013025:Glycine max / Q000737:chemistry*
chemical_list: D002241:Carbohydrates; D010940:Plant Proteins
keywords: by-product; correlation; molecular structure; nutrient; spectral information