Extração de hemicelulose e açúcares fermentáveis do bagaço, colmo e folha do sorgo sacarino
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Data
2020-10-05
Autores
Martins, Rodrigo Pagano
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Universidade Estadual Paulista (Unesp)
Resumo
O sorgo sacarino é uma alternativa viável para a produção de etanol devido a sua grande produção de caldo e bagaço. O bagaço pode ser queimado para a produção de vapor e energia elétrica, porém, estudos mostram que existem aplicações mais importantes para essa biomassa e outras frações da planta. A estrutura lignocelulósica da biomassa pode ser desestruturada para disponibilizar seus principais componentes - celulose, hemicelulose e lignina. Esses componentes também podem ser hidrolisados até suas unidades formadoras. O presente estudo usou o bagaço, o colmo e a folha de sorgo sacarino e procurou determinar a influência de diferentes pré-tratamentos na extração de hemicelulose na forma de polissacarídeo (xilana) e monossacarídeo (xilose). A extração da xilana foi realizada utilizando-se métodos alcalinos com H2O2 6 % e 10 %, NaOH 10 % e KOH 10 %. Para extração de xilose foi utilizado um pré-tratamento com H2SO4 1%. Os materiais pré-tratados foram submetidos à hidrólise enzimática para determinação do rendimento de conversão de celulose em glicose. O bagaço, colmo e folha in natura apresentaram proporção de celulose de 43,58 %, 42,23 % e 35,09 %. A proporção de hemicelulose foi de 24,51 %, 22,14 % e 20,51 %, e a de lignina de 26,22 %, 20,92 % e 19,93 %. O rendimento de xilana variou de 17,79 % no pré-tratamento do colmo com H2O2 6 % e 96,8 % no pré-tratamento do colmo com NaOH 10 %. A hidrólise enzimática do material pré-tratado apresentou porcentagem de conversão de celulose em glicose entre 20,69 % no resíduo do bagaço pré-tratado com ácido diluído e 92,58 % no resíduo da folha pré-tratada com NaOH 10 %. Todas as biomassas apresentaram alto rendimento de extração de hemicelulose empregando os pré-tratamentos com peróxido de hidrogênio 10 % e hidróxido de sódio 10 %. A hidrólise enzimática resultou em rendimento superior a 90 % para as três biomassas pré-tratadas com peróxido de hidrogênio 10 % e acima de 80 % para as biomassas pré-tratadas com hidróxido de potássio 10 %. O sorgo sacarino tem potencial para a produção macromoléculas como a xilana e glucana e para a produção de açúcares fermentáveis como a xilose e glicose.
Sweet sorghum is a viable alternative for ethanol production due to its large production of juice and bagasse. Bagasse can be burned to produce steam and electricity. However, studies shows there are more important applications for this biomass and other plant fractions. The lignocellulosic structure of the biomass can be broken down to make its main components available - cellulose, hemicellulose and lignin. These components can also be hydrolyzed to their forming units. The present study used sweet sorghum bagasse, stalks and leaves and sought to determine the influence of different pretreatments in the extraction of hemicellulose in the form of polysaccharide (xylan) and monosaccharide (xylose). Xylan extraction was performed using alkaline methods with 6% and 10% H2O2, 10% NaOH and 10% KOH. For xylose extraction, a pretreatment with 1% H2SO4 was used. The pretreated materials were subjected to enzymatic hydrolysis to determine the conversion efficiency of cellulose to glucose. Untreated bagasse, stalks and leaves of sweet sorghum presented a proportion of cellulose of 43.58%, 42.23% and 35.09%. The proportion of hemicellulose was 24.51%, 22.14% and 20.51%, and that of lignin 26.22%, 20.92% and 19.93%. The xylan yield varied from 17.79% in stalks pretreatment with 6% H2O2 and 96.8% in stalks pretreatment with 10% NaOH. The enzymatic hydrolysis of the pretreated material showed a percentage of conversion of cellulose to glucose between 20.69% in pretreated bagasse with diluted sulfuric acid and 92.58% in pretreated leaves with 10% NaOH. All biomasses presented high hemicellulose extraction yield using pretreatments with 10% H2O2 and 10% NaOH. Enzymatic hydrolysis resulted in a yield greater than 90% for the three biomasses pretreated with 10% H2O2 and above 80% for the biomasses pretreated with 10% KOH. Sweet sorghum has great potential to produce macromolecules like xylan and glucan and to produce fermentable sugars like xylose and glucose.
Sweet sorghum is a viable alternative for ethanol production due to its large production of juice and bagasse. Bagasse can be burned to produce steam and electricity. However, studies shows there are more important applications for this biomass and other plant fractions. The lignocellulosic structure of the biomass can be broken down to make its main components available - cellulose, hemicellulose and lignin. These components can also be hydrolyzed to their forming units. The present study used sweet sorghum bagasse, stalks and leaves and sought to determine the influence of different pretreatments in the extraction of hemicellulose in the form of polysaccharide (xylan) and monosaccharide (xylose). Xylan extraction was performed using alkaline methods with 6% and 10% H2O2, 10% NaOH and 10% KOH. For xylose extraction, a pretreatment with 1% H2SO4 was used. The pretreated materials were subjected to enzymatic hydrolysis to determine the conversion efficiency of cellulose to glucose. Untreated bagasse, stalks and leaves of sweet sorghum presented a proportion of cellulose of 43.58%, 42.23% and 35.09%. The proportion of hemicellulose was 24.51%, 22.14% and 20.51%, and that of lignin 26.22%, 20.92% and 19.93%. The xylan yield varied from 17.79% in stalks pretreatment with 6% H2O2 and 96.8% in stalks pretreatment with 10% NaOH. The enzymatic hydrolysis of the pretreated material showed a percentage of conversion of cellulose to glucose between 20.69% in pretreated bagasse with diluted sulfuric acid and 92.58% in pretreated leaves with 10% NaOH. All biomasses presented high hemicellulose extraction yield using pretreatments with 10% H2O2 and 10% NaOH. Enzymatic hydrolysis resulted in a yield greater than 90% for the three biomasses pretreated with 10% H2O2 and above 80% for the biomasses pretreated with 10% KOH. Sweet sorghum has great potential to produce macromolecules like xylan and glucan and to produce fermentable sugars like xylose and glucose.
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Biomassa, Xilana, Sorgo sacarino, Pré-tratamento, Hidrólise enzimática, Biomass, Xylan, Sweet sorghum, Pretreatment, Enzymatic hydrolysis, Pré-tratamento alcalino e ácido diluído, Xilose, Glicose, Diluted acid and alkaline pretreatment, Xylose, Glucose