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- Métodos de fraccionamento de biomassa para as biorrefinariasPublication . Carvalheiro, Florbela; Duarte, Luís C.; Lukasik, Rafal M.; Moniz, PatriciaO desenvolvimento de processos que permitam o fraccionamento eficiente da biomassa (tradicionalmente designados por pré-tratamentos) constitui uma parte muito significativa do esforço científico que tem sido feito para a transformação das biorrefinarias numa realidade industrial. Este artigo apresenta uma breve revisão dos processos de fraccionamento, sendo dada particular atenção a processos emergentes, discutindo também as suas possíveis vantagens e limitações.
- Deconstruction of the hemicellulose fraction from lignocellulosic materials into simple sugarsPublication . Gírio, Francisco; Carvalheiro, Florbela; Duarte, Luís C.; Lukasik, Rafal M.Hemicelluloses hold a great promise for the production of added-value compounds in the biorefinery framework. Specifically, the xylan-rich hemicelluloses from hardwoods and agro-industrial residues present themselves as effective feedstock choices for the biotechnological production of xylitol. This paper reviews the various hemicellulose structures present in such materials and critically evaluates the available processing options to produce xylose-rich fermentable hydrolysates. Currently, acid-based processes still present the best trade-off between operation easiness and xylose yield and recovery. Nevertheless, concerns regarding the impact of the fractionation processes on the overall upgradability of all biomass fractions (namely, cellulose and specially lignin) may turn the route to other strategies. Specifically, the combined/sequential use of processes targeting hemicellulose dissolution and hydrolysis might hold great promise for the economical production of pentoses.
- Industry-based biorefineriesPublication . Cabrita, Isabel; Carvalheiro, Florbela; Duarte, Luís C.; Gírio, Francisco; Lukasik, Rafal M.
- Nanofiltration and reverse osmosis as a platform for production of natural botanic extracts: the case study of carob by-productsPublication . Almanasrah, Mohammad; Brazinha, Carla; Kallioinen, Mari; Duarte, Luís C.; Roseiro, Luisa B.; Lukasik, Rafal M.; Carvalheiro, Florbela; Manttari, Mika; Crespo, JoãoCarob kibbles are a low-cost and renewable source of economically relevant phenolic compounds (high value catechin and its derivatives and gallic acid) and abundant in small sugars. This work aims at producing two distinct natural extracts from carob kibbles, one extract enriched in catechin and its derivatives for the nutraceuticals market and an extract enriched in sugars for the food industry. This valorisation strategy involves an integrated process based on membrane technology that fulfils the zero discharge principle and may be applied to other agro-industrial by-products. Different aqueous extraction schemes were considered (a one-step process and a two-steps approach). The aqueous extracts obtained were fractionated by diananofiltration and the fractions obtained were evaluated in terms of their content in target products. An integrated scheme for production of fractionated extracts is proposed based on the experimental work developed assuring, simultaneously, a minimal use of resources and emission of waste.
- Selective recovery of phenolic compounds and carbohydrates from carob kibbles using water-based extractionPublication . Almanasrah, Mohammad; Roseiro, Luisa B.; Lukasik, Rafal M.; Carvalheiro, Florbela; Brazinha, Carla; Crespo, João; Kallioinen, Mari; Manttari, Mika; Duarte, Luís C.Carob kibbles are an important renewable source of valuable compounds, such as fermentable sugars and phenolic compounds. However, the selective recovery of these compounds is not a trivial task. In this work, a strategy was developed to enable the recovery of both classes of compounds by means of awater-based extraction.One-step extraction recovered only approximately 20% of the phenolic compounds, corresponding to an extraction yield of 0.6 g Gallic acid equivalents (GAE)/100 g dry mass of carob kibbles. The obtained extract contained a significant amount of carbohydrates (110 g/L). The alternative two-step extraction developed enabled higher compound selectivity together with an increase in the yield of the phenolic compounds to about 70%, corresponding to 1.9 gGAE/100 g carob dry matter.The two-step extraction was easily scaled-up and is an effective method to obtain significantly sepa-rated carbohydrates and polyphenol-rich streams that can be further processed, e.g., in biorefineries orfood industries, respectively.
- Produção de xilitol: uma via alternativa de valorização do bagaço de azeitona extratadoPublication . Duarte, Luís C.; Carvalheiro, Florbela; Torrado, Ivone; Guerra, Vera; Morais, Ana Rita C.; Ferreira, Cátia; Roseiro, Luisa B.; C. Fernandes, M.; Neves, Luísa A.; Brás, Teresa; Lourenço, Pedro; Lukasik, Rafal M.; Pinto, Filomena
- Pre-treatment of lignocellulosic biomass using ionic liquids: wheat straw fractionationPublication . Lopes, André; João, Karen; Rubik, Djonatam; Bogel-Lukasik, Ewa; Duarte, Luís C.; Andreaus, Jurgen; Lukasik, Rafal M.This work is devoted to study pre-treatment methodologies of wheat straw with 1-ethyl-3-methylimidazolium acetate ([emim][CH3COO]) and subsequent fractionation to cellulose, hemicellulose and lignin. The method developed and described here allows the separation into high purity carbohydrate and lignin fractions and permits an efficient IL recovery. A versatility of the established method was confirmed by the IL reuse. The fractionation of completely dissolved biomass led to cellulose-rich and hemicellulose-rich fractions. A high purity lignin was also achieved. To verify the potential further applicability of the obtained carbohydrate-rich fractions, and to evaluate the pre-treatment efficiency, the cellulose fraction resulting from the treatment with [emim][CH3COO] was subjected to enzymatic hydrolysis. Results showed a very high digestibility of the cellulose samples and confirmed a high glucose yield for the optimized pre-treatment methodology.
- Desenvolvimento de processos de pré-tratamento da biomassa para a separação eficiente das correntes de lenhina e de açúcaresPublication . Carvalheiro, Florbela; Lukasik, Rafal M.; Duarte, Luís C.; Roseiro, Luisa B.; Ribeiro, Belina; Marques, Susana; Bernardo, Joana; Van-Dúnem, Vanmira; Pires, Filipa; Costa, Diogo; Sanfins, Luís; Gírio, FranciscoRESUMO: O fracionamento da biomassa é um dos principais pontos críticos no desenvolvimento das biorrefinarias. Neste trabalho, são apresentadas três estratégias inovadoras com vista à separação seletiva das frações de celulose, hemicelulose e lenhina, utilizando compostos orgânicos, geralmente em solução aquosa: i) utilização de líquidos iónicos (ILs) em particular [emim][OAc] e [emim][HSO4]); ii) processos organosolv baseados na utilização de misturas etanol:água (50:50); e iii) um processo não aquoso baseado em imidazole. Os processos com ILs permitiram um fracionamento diferencial e, em geral, uma redução da cristalinidade da celulose. Os processos organosolv permitiram modular a distribuição de produtos derivados da hemicelulose e da lenhina entre as fases sólida e líquida. A utilização de imidazole, permitiu a separação das duas frações de polissacáridos e contribuiu para despolimerização da lenhina.