Avaliação da extração de hemicelulose e da produção de xilooligossacarídeos a partir de um subproduto de Eucalyptus oriundo de uma empresa de celulose
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Data
2017-11-23
Autores
Mafei, Thamyres Del Torto
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Universidade Estadual Paulista (Unesp)
Resumo
A madeira de Eucalyptus é aplicada principalmente na cogeração de energia, na alimentação animal, na produção de carvão vegetal e na produção de celulose. Um subproduto de Eucalyptus gerado em fábricas de celulose é utilizado principalmente para cogeração de energia, porém o mesmo apresenta um grande potencial a ser estudado, pois tem um elevado teor de celulose e hemicelulose. Uma alternativa é a produção de xilooligossacaródeos (XOS) a partir do subproduto de Eucalyptus. Os XOS são responsáveis por diversos efeitos benéficos como a prevenção de cáries, a diminuição de níveis séricos de colesterol e o estímulo do crescimento de bifidobactérias no trato gastrointestinal. Objetivo: O presente trabalho propôs avaliar a produção de XOS via hidrólise enzimática de um subproduto de Eucalyptus oriundo de uma empresa de celulose. Métodos: A parte experimental envolveu a obtenção de um subproduto de Eucalyptus oriundo do processamento de toras de madeira. O subproduto foi moído e extraído com etanol e posteriormente pré-tratado com clorito de sódio. Os subprodutos, extraído (SE) e extraído e pré tratado (SEP), foram submetidos a um processo de extração de hemicelulose. As hemiceluloses, hemicelulose extraído do subproduto extraído-moido (HSE) e hemicelulose extraído do subproduto extraído e pré-tratado (HSEP) e os subprodutos (SE e SEP) foram caracterizados quimicamente em relação aos teores de celulose, hemicelulose e lignina. Além disso, as hemiceluloses obtidas (HSE e HSEP) e os subprodutos (SE e SEP) foram hidrolisados enzimaticamente utilizando os extratos comerciais Cellulase (Sigma), Celluclast (Novozymes) e Xilanases (Verdartis) para avaliar a produção de XOS. Resultados: O SE e o SEP apresentaram teores de celulose (45,6% e 43,6%), hemicelulose (17,7% e 16,6%) e lignina (28,5% e 14,6%), respetivamente. O SEP apresentou um teor de lignina cerca de 50% inferior ao SE, o que confirma a eficiência deste pré-tratamento no processo de deslignificação. Além disso, os dados indicaram que o pré-tratamento foi seletivo para remoção da lignina. As HSE e HSEP extraídas apresentaram teores de hemicelulose de 23,7% e 57,1%, respectivamente. A hidrólise enzimática do SE e do SEP culminaram em conversões máximas de xilana em XOS de 8,5% e 16,1%, respectivamente. O SE apresentou uma conversão limitada de xilana em XOS, enquanto o SEP mostrou uma conversão mais intensa. Entretanto, a hidrólise enzimática da HSE e da HSEP mostraram conversões máximas de xilana em XOS de 13,7% e 30,8%, respectivamente. Todavia, a concentração máxima de XOS na hidrólise enzimática da HSE e da HSEP foram de 0,56 g.L-1 e 3,39 g.L-1, respectivamente. A hidrólise enzimática de uma hemicelulose comercial de Birchwood culminou em uma conversão e concentração máxima de XOS de 30% e 3,48 g.L-1, respectivamente. Conclusão: A formação de XOS no processo de hidrólise enzimática foi mais eficiente frente à HSEP e a hemicelulose comercial de Birchwood quando comparado a HSE. Todavia, a produção de XOS a partir de HSE pode ser uma estratégia para melhor aproveitamento do subproduto em estudo.
Eucalyptus wood is mainly applied to energy cogeneration production, animal feed, charcoal production and pulp production. A byproduct of Eucalyptus generated in pulp mills is mainly used for energy cogeneration, but it has a great potential to be studied because it has a high content of cellulose and hemicellulose. An alternative is the production of XOS from the Eucalyptus byproduct. The XOS are responsible for several beneficial effects such as caries prevention, decreased serum cholesterol levels and stimulation of the growth of bifidobacteria in the gastrointestinal tract. Objective: The present work proposed to evaluate the XOS production through enzymatic hydrolysis of a by-product of Eucalyptus from a cellulose company. Methods: The experimental part involved the obtaining of a by-product of Eucalyptus from the processing of wood logs. The by-product was ground and extracted with ethanol and then pretreated with sodium chlorite. The by-products, extracted (SE) and extracted and pre-treated (SEP), were submitted to a hemicellulose extraction process. Hemicelluloses, hemicellulose extracted from the ground-extracted by-product (HSE) and hemicellulose extracted from the pre-treated by-product (HSEP) and by-products (SE and SEP) were chemically characterized in relation to the contents of cellulose, hemicellulose and lignina. In addition, the obtained hemicelluloses (HSE and HSEP) and by-products (SE and SEP) were enzymatically hydrolyzed using the commercial extracts Cellulase (Sigma), Celluclast (Novozymes) and Xilanases (Verdartis) to evaluate to evaluate the production of XOS.Results: SE and SEP presented cellulose contents (45.6% and 43.6%), hemicellulose (17.7% and 16.6%) and lignin (28.5% and 14.6%), respectively. The SEP presented a lignin content about 50% lower than the SE, which confirms the efficiency of this pretreatment in the delignification process. In addition, the data indicated that pretreatment was selective for lignin removal. The HSE and HSEP extracted had hemicellulose contents of 23.7% and 57.1%, respectively. The enzymatic hydrolysis of SE and SEP showed maximum conversions of xylan in XOS of 8.5% and 16.1%, respectively. SE showed a limited conversion of xylan to XOS, whereas SEP showed a more intense conversion. However, the enzymatic hydrolysis of HSE and HSEP showed maximum conversions of xylan in XOS of 13.7% and 30.8%, respectively. However, the maximum concentrations of XOS in the enzymatic hydrolysis of HSE and HSEP were 0.56 g.L-1 and 3.39 g.L-1, respectively. Enzymatic hydrolysis of a commercial Birchwood hemicellulose showed conversion and maximum concentration of XOS of 30% and 3.48 g.L-1, respectively. Conclusion: T The formation of XOS in the enzymatic hydrolysis process was more efficient than HSEP and the commercial hemicellulose of Birchwood when compared to HSE. However, the production of XOS from HSE may be a strategy for better utilization of the by-product under study.
Eucalyptus wood is mainly applied to energy cogeneration production, animal feed, charcoal production and pulp production. A byproduct of Eucalyptus generated in pulp mills is mainly used for energy cogeneration, but it has a great potential to be studied because it has a high content of cellulose and hemicellulose. An alternative is the production of XOS from the Eucalyptus byproduct. The XOS are responsible for several beneficial effects such as caries prevention, decreased serum cholesterol levels and stimulation of the growth of bifidobacteria in the gastrointestinal tract. Objective: The present work proposed to evaluate the XOS production through enzymatic hydrolysis of a by-product of Eucalyptus from a cellulose company. Methods: The experimental part involved the obtaining of a by-product of Eucalyptus from the processing of wood logs. The by-product was ground and extracted with ethanol and then pretreated with sodium chlorite. The by-products, extracted (SE) and extracted and pre-treated (SEP), were submitted to a hemicellulose extraction process. Hemicelluloses, hemicellulose extracted from the ground-extracted by-product (HSE) and hemicellulose extracted from the pre-treated by-product (HSEP) and by-products (SE and SEP) were chemically characterized in relation to the contents of cellulose, hemicellulose and lignina. In addition, the obtained hemicelluloses (HSE and HSEP) and by-products (SE and SEP) were enzymatically hydrolyzed using the commercial extracts Cellulase (Sigma), Celluclast (Novozymes) and Xilanases (Verdartis) to evaluate to evaluate the production of XOS.Results: SE and SEP presented cellulose contents (45.6% and 43.6%), hemicellulose (17.7% and 16.6%) and lignin (28.5% and 14.6%), respectively. The SEP presented a lignin content about 50% lower than the SE, which confirms the efficiency of this pretreatment in the delignification process. In addition, the data indicated that pretreatment was selective for lignin removal. The HSE and HSEP extracted had hemicellulose contents of 23.7% and 57.1%, respectively. The enzymatic hydrolysis of SE and SEP showed maximum conversions of xylan in XOS of 8.5% and 16.1%, respectively. SE showed a limited conversion of xylan to XOS, whereas SEP showed a more intense conversion. However, the enzymatic hydrolysis of HSE and HSEP showed maximum conversions of xylan in XOS of 13.7% and 30.8%, respectively. However, the maximum concentrations of XOS in the enzymatic hydrolysis of HSE and HSEP were 0.56 g.L-1 and 3.39 g.L-1, respectively. Enzymatic hydrolysis of a commercial Birchwood hemicellulose showed conversion and maximum concentration of XOS of 30% and 3.48 g.L-1, respectively. Conclusion: T The formation of XOS in the enzymatic hydrolysis process was more efficient than HSEP and the commercial hemicellulose of Birchwood when compared to HSE. However, the production of XOS from HSE may be a strategy for better utilization of the by-product under study.
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Palavras-chave
Subproduto de Eucalyptus, Pré-tratamento, Composição química, Hemicelulose, Hidrólise enzimática e Xilooligossacarídeos.