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Authors
Abstract(s)
O mercado do café, um dos mais proeminentes a nível mundial, é um pilar importante na economia de países exportadores como a Colômbia, Vietname e Brasil. Porém, as alterações climáticas têm resultado em graves consequências nos ecossistemas em geral e na produção de café em particular. O projeto TriCafé tem contribuído para a recuperação da floresta húmida tropical na Serra da Gorongosa (parte do Parque Nacional da Gorongosa) em Moçambique, que viu a sua biodiversidade ameaçada no passado, com impacto sócio-económico nas comunidades vizinhas. A plantação de cafeeiros, num sistema agroflorestal na Serra da Gorongosa, tem sido um dos focos desse projeto. De forma a contribuir para a avaliação da qualidade do grão produzido nesse sistema agroflorestal, este trabalho centrou-se na extração e caraterização parcial de compostos bioativos, em particular polissacáridos, a partir de grão verde de plantas Coffea arabica L., cultivadas a dois níveis de altitude, com sombreamento moderado. Os extratos obtidos por extração por micro-ondas (MAE) apresentaram, geralmente, conteúdos de biocompostos e atividade antioxidante superiores aos das frações de extração por multi-etapas (MSE). Os resultados evidenciaram redução de proteínas e da maioria dos polissacáridos no grão com o aumento da altitude de cultivo. Adicionalmente, os extratos MAE e FKOH (fração obtida por MSE) não revelaram atividade contra Escherichia coli e Staphylococcus aureus. A partir dos extratos com maior concentração de polissacáridos (MAE e FKOH) foi possível fracionar por cromatografia de exclusão molecular, polissacáridos de Mr >2000 kDa e ca. 40 kDa. Estes últimos apresentaram atividade antioxidante e foram co-eluidos com proteínas, sugerindo existência na forma livre ou complexada. Os extratos MAE e MSE analisados por HPLC-RI exibiram sacarose, glucose, frutose e arabinose, enquanto a estaquiose e maltotriose foram detetadas apenas em algumas frações MSE. Os extratos hidrolisados revelaram glucose, manose e arabinose, resultados parcialmente confirmados por cromatografia em camada fina.
The coffee market, one of the most prominent in the world, is an important pillar in the economy of exporting countries such as Colombia, Vietnam and Brazil. However, climate change has resulted in serious consequences for ecosystems in general and coffee production in particular. The TriCafé project has contributed to the recovery of the tropical rainforest in Mount Gorongosa (part of the Gorongosa National Park) in Mozambique, which saw its biodiversity threatened in the past, with a socio-economic impact on neighboring communities. Planting coffee trees, in an agroforestry system in Mount Gorongosa, has been one of the focuses of this project. To contribute to the evaluation of the quality of the grain produced in this agroforestry system, this work focused on the extraction and partial characterization of bioactive compounds, in particular polysaccharides, from green grain of Coffea arabica L. plants, cultivated at two levels high altitude, with moderate shading. The extracts obtained by microwave extraction (MAE) generally presented higher biocompound content and antioxidant activity than the multi-step extraction (MSE) fractions. The results showed a reduction in proteins and most polysaccharides in the grain with increasing cultivation altitude. Additionally, MAE and FKOH (fraction obtained by MSE) extracts did not reveal activity against Escherichia coli and Staphylococcus aureus. From the extracts with the highest concentration of polysaccharides (MAE and FKOH) it was possible to fractionate by molecular exclusion chromatography, polysaccharides with Mr >2000 kDa and ca. 40 kDa. The latter showed anti-oxidant activity and were co-eluted with proteins, suggesting their existence in free or complexed form. The MAE and MSE extracts analyzed by HPLC-RI exhibited sucrose, glucose, fructose and arabinose, while stachyose and maltotriose were detected only in some MSE fractions. The hydrolyzed extracts revealed glucose, mannose, and arabinose, results partially confirmed by thin layer chromatography.
The coffee market, one of the most prominent in the world, is an important pillar in the economy of exporting countries such as Colombia, Vietnam and Brazil. However, climate change has resulted in serious consequences for ecosystems in general and coffee production in particular. The TriCafé project has contributed to the recovery of the tropical rainforest in Mount Gorongosa (part of the Gorongosa National Park) in Mozambique, which saw its biodiversity threatened in the past, with a socio-economic impact on neighboring communities. Planting coffee trees, in an agroforestry system in Mount Gorongosa, has been one of the focuses of this project. To contribute to the evaluation of the quality of the grain produced in this agroforestry system, this work focused on the extraction and partial characterization of bioactive compounds, in particular polysaccharides, from green grain of Coffea arabica L. plants, cultivated at two levels high altitude, with moderate shading. The extracts obtained by microwave extraction (MAE) generally presented higher biocompound content and antioxidant activity than the multi-step extraction (MSE) fractions. The results showed a reduction in proteins and most polysaccharides in the grain with increasing cultivation altitude. Additionally, MAE and FKOH (fraction obtained by MSE) extracts did not reveal activity against Escherichia coli and Staphylococcus aureus. From the extracts with the highest concentration of polysaccharides (MAE and FKOH) it was possible to fractionate by molecular exclusion chromatography, polysaccharides with Mr >2000 kDa and ca. 40 kDa. The latter showed anti-oxidant activity and were co-eluted with proteins, suggesting their existence in free or complexed form. The MAE and MSE extracts analyzed by HPLC-RI exhibited sucrose, glucose, fructose and arabinose, while stachyose and maltotriose were detected only in some MSE fractions. The hydrolyzed extracts revealed glucose, mannose, and arabinose, results partially confirmed by thin layer chromatography.
Description
Trabalho final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica – Perfil de Bioprocessos
Keywords
Coffea arabica L. Compostos bioativos Cromatografia de exclusão molecular HPLC-RI Polissacáridos Coffea arabica L. Bioactive compounds Size exclusion chromatography HPLC-RI Polysaccharides
Citation
PIMENTA, Sara Roseira - Extração e caracterização de polissacáridos isolados do grão de café da Gorongosa. Lisboa: Instituto Superior de Engenharia de Lisboa, 2023. Dissertação de Mestrado.