Structural and chemical analysis of native and malted barley kernels by polarized Raman spectroscopy (PRS)

Leonardo Galvis, Carlo G. Bertinetto, Ulla Holopainen, Tarja Tamminen, Tapani Vuorinen

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)

Abstract

In this work, barley kernel sections embedded in resin were mapped using polarized Raman spectroscopy (PRS) for evaluation of both chemical and structural changes in endosperm upon malting. A multivariate analysis that includes Band-Target Entropy Minimization (BTEM) was used to resolve the individual spectrum of components present on sections and to reconstruct images based on their relative signal. BTEM-resolved spectra matched with several individual model compound spectra that allowed the identification of protein, starch, non-starch carbohydrates, esterified ferulic acid and embedding media. Raman images also revealed chemical changes in the cell walls within starchy endosperm and inside cells due to enzymatic reactions in malting. The anisotropic response of the C–O–C Raman band associated with the orientation of ordered structures inside starch granules remains despite a notorious shape distortion of large starch granules.
Original languageEnglish
Pages (from-to)73-80
Number of pages8
JournalJournal of Cereal Science
Volume62
DOIs
Publication statusPublished - Mar 2015
MoE publication typeA1 Journal article-refereed

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Keywords

  • AFM
  • Atomic force microscopy
  • BTEM
  • Band-Target Entropy Minimization
  • CV
  • Chemical imaging
  • Coefficient of Variation
  • LLS
  • Linear least-squares fit
  • Malting
  • Multivariate analysis
  • PRS
  • Polarized Raman Spectroscopy
  • Polarized Raman spectroscopy
  • SD
  • Standard Deviation

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