On-line ISSN 0717-9200
AFFONSO SAMPAIO, Danielle, DOS SANTOS ABREU, Heber, SILVEIRA AUGUSTO, Leonardo Davi et al. Approach on the integument lignin profile of seeds of Araucaria angustifolia. Bosque (Valdivia), 2016, vol.37, no.3, p.549-555. ISSN 0717-9200.
The aim of this research was to quantify and identify the types of lignin and characterize its functionalization based on apparent physical resistance in each seed coat layers of Araucaria angustifolia. Each seed layer (exotesta, mesotesta and endotesta) was milled, homogenized and pre-extracted with solvents: cyclohexane, ethyl acetate and methanol for quantification of lignin. Pre-treatment with NaOH 1% was also performed in each layer of the seed for lignin quantification and for infrared spectroscopy. The lignin content obtained in the testa was 32.43 % for the three layers. After alkaline treatment, the lignin content was 31.52 % in exotesta, 16.88 % in mesotesta and 15.48 % in endotesta. Dioxane lignin was isolated from the seed coat and reduced with NaHB4. Infrared spectra (FTIR) were obtained from the dioxane lignin, reduced dioxane lignin and alkaline-treated Klason lignin of each layer. Microscopic analyses of the in natura exotesta and mesotesta layers from the seed coat were performed through histochemical test (Wiesner) and fluorescence microscopy. Infrared analyses made possible observation of aldehyde terminations in dioxane lignin and propose the structural profile of Klason lignin in different layers. Fluorescence microscopic analyses allowed identification of highly lignified macrosclereids in exotesta.
Keywords: lignin; nut; infrared; lignina; piñón; infrarrojo; testa.
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