Advisor(s)
Abstract(s)
Resumo
O presente estudo avalia a composição química
detalhada do engaço da uva de modo a encontrar novas formas
para a sua valorização. O engaço da uva é um subproduto
vinícola de origem lenhocelulósica, com 30-31% de celulose,
21% de hemicelulose, 17-18% de lenhina, 15-16% de taninos
e cerca de 6,0% de proteínas. A análise dos monossacarídeos
mostrou que, a seguir à celulose, a xilana é o segundo
polissacarídeo mais abundante no engaço (ca. 12%). A
celulose foi isolada pelo método Kürscher e Hoffer e foi
caracterizada por difração de raios-X (DRX). Esta análise
revelou a existência de uma célula unitária típica de celulose I
com um elevado grau de cristalinidade (ca. 75%). Também foi
possível verificar uma elevada abundância de compostos
extratáveis em água (ca. 24%), atribuídos principalmente a
sais inorgânicos solúveis, taninos hidrolisáveis e pectinas. A
lenhina Klason foi caracterizada por espectroscopia de
infravermelho e espectroscopia de ressonância magnética tendo-se verificado tratar-se de uma lenhina do tipo HGS, com
predominância de unidades guaiacilo.
Abstract The present study evaluates the detailed chemical composition of grape stalks to find new forms of recovery. Grape stalk is a by-product from winemaking process of lignocellulosic source with 30-31% cellulose, 21% hemicellulose, 17-18% lignin, 15-16% tannin and about 6.0% protein. Analysis of monosaccharides showed that, after cellulose, the xylan is the second most abundant polysaccharide in stalks (ca. 12%). Cellulose was isolated by the Kürscher and Hoffer method and was characterized by X-ray diffraction (XRD). This analysis revealed the existence of a typical unit cell of cellulose I with a high degree of crystallinity (ca. 75%). It was also observed a high abundance of water extractable compounds (ca. 24%), attributed to mainly soluble inorganic salts, hydrolysable tannins and pectins. Klason Lignin was characterized by infrared spectroscopy and magnetic resonance spectroscopy and it was found that this is a HGS lignin-type, predominantly with guaiacyl units.
Abstract The present study evaluates the detailed chemical composition of grape stalks to find new forms of recovery. Grape stalk is a by-product from winemaking process of lignocellulosic source with 30-31% cellulose, 21% hemicellulose, 17-18% lignin, 15-16% tannin and about 6.0% protein. Analysis of monosaccharides showed that, after cellulose, the xylan is the second most abundant polysaccharide in stalks (ca. 12%). Cellulose was isolated by the Kürscher and Hoffer method and was characterized by X-ray diffraction (XRD). This analysis revealed the existence of a typical unit cell of cellulose I with a high degree of crystallinity (ca. 75%). It was also observed a high abundance of water extractable compounds (ca. 24%), attributed to mainly soluble inorganic salts, hydrolysable tannins and pectins. Klason Lignin was characterized by infrared spectroscopy and magnetic resonance spectroscopy and it was found that this is a HGS lignin-type, predominantly with guaiacyl units.
Description
Keywords
Engaço da uva Celulose Lenhina Xilanas Grape stalks Xylan Cellulose Lignin
Citation
Prozil, Sónia; Mendes, Joana; Evtuguin, Dmitry & Lopes, Luísa P. Cruz (2013). Caracterização do Engaço da Uva e Avaliação do seu Potencial como Matéria‐Prima Lenhocelulósica. Millenium, 44 (janeiro/junho). Pp. 23‐40