Endosperm and aleurone cell structure in barley and wheat as studied by optical and Raman microscopy

Anna-Stiina Jääskeläinen, Ulla Holopainen-Mantila, Tarja Tamminen, Tapani Vuorinen

    Research output: Contribution to journalArticleScientificpeer-review

    68 Citations (Scopus)


    Grain ultrastructure is of utmost importance when designing grain processing procedures in the food industry. In this study, wheat and barley grain components were localised using optical and Raman microscopy. The optical microscopic analyses were performed using several selective stains to localise β-glucan, protein and starch or autofluorescence to image the ferulic acid and other fluorescing substances. Alternatively, Raman microscopy was applied to localise the grain components without any need for preceding staining or other sample pretreatment. Both methods provided consistent information on the grain structures, illustrating the distribution of polysaccharides, aromatics and protein in endosperm and aleurone layers. In aleurone layers of both barley and wheat, a distinct difference between the anticlinal and periclinal cell walls was observed. The anticlinal cell walls were enriched with aromatic substances which were present in remarkably lower concentrations in the inner periclinal cell walls but for barley, an even higher concentration in the outer periclinal cell wall was observed. In addition, Raman spectroscopy illustrated the detailed distribution of substances across the aleurone cell walls: β-glucan was adjacent to proteins and it was deficient in the middle lamella whereas arabinoxylan was enriched in the outer cell wall layers and middle lamella.
    Original languageEnglish
    Pages (from-to)543-550
    JournalJournal of Cereal Science
    Issue number3
    Publication statusPublished - May 2013
    MoE publication typeA1 Journal article-refereed


    • Cell wall
    • Grain ultrastructure
    • Optical microscopy
    • Raman spectroscopy


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