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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Avalia??o do efeito das vari?veis de processo na descafeiniza??o da erva-mate por extra??o com fluido supercr?tico / Evaluation of the effect of process variables in decaffeination of yerba mate by extraction with supercritical fluid

Franceschini, Gustavo do Nascimento 30 March 2017 (has links)
Submitted by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-06-29T13:46:52Z No. of bitstreams: 1 DIS_GUSTAVO_DO_NASCIMENTO_FRANCESCHINI_COMPLETO.pdf: 1349176 bytes, checksum: 447176549ff68fd480d9db42406285d0 (MD5) / Made available in DSpace on 2017-06-29T13:46:52Z (GMT). No. of bitstreams: 1 DIS_GUSTAVO_DO_NASCIMENTO_FRANCESCHINI_COMPLETO.pdf: 1349176 bytes, checksum: 447176549ff68fd480d9db42406285d0 (MD5) Previous issue date: 2017-03-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq / The caffeine extraction process of yerba mate presents itself as an economically attractive activity, capable of generating two products with high market value, decaffeinated yerba mate, a differentiated product and natural caffeine, a compound with a growing demand in the current market. The purpose of this study was to evaluate the effect of the properties of plant material and the effect of process operating conditions in the caffeine removal from mate through supercritical extraction. To this objective, supercritical carbon dioxide extraction technology was used. The studied characteristics of the plant material were particle size, density and moisture content. After the optimum parameters were defined, the effect of the processing to which yerba mate is submitted was also evaluated, in three different stages: harvesting, zapecado and cancheamento. As for the operating conditions, it was assessed the influence of the porosity and the cosolvent content (ethanol) during the extraction process, with the pressure and operating temperature were set at optimum values for the removal of caffeine. Still, the effect of the mass ratio plant / solvent weight used was also studied. The extracts were analyzed by highperformance liquid chromatography. It was observed that increasing water content present in plant favored removal of caffeine, reaching a final concentration of 0.30% of caffeine (g / 100g), while the use of ethanol as cosolvent during the extraction process yielded in a final concentration of 0.03% (g / 100g) caffeine. For the processing, the zapecada sample presented the best results overall, both in yield of extract obtained and caffeine removal. Regarding the biological activity of the decaffeinated product, it was verified that the infusions of yerba mate decreased the cell viability of different cell lines of esophageal cancer and that this effect was independent of the concentration of caffeine present in the plant. Finally, the mathematical modeling of the extraction curve was performed in order to correlate the variables of the process with the experimental data. / O processo de extra??o de cafe?na da erva-mate apresenta-se como uma atividade economicamente atrativa, capaz de gerar dois produtos com alto valor de mercado, a erva-mate descafeinada, um produto diferenciado e a cafe?na natural, composto com uma crescente demanda no mercado atual. A proposta deste trabalho foi avaliar o efeito das propriedades do material vegetal e das condi??es operacionais de processo de extra??o na remo??o da cafe?na da erva-mate. Para isto, utilizou-se a tecnologia de extra??o supercr?tica. As propriedades do material vegetal estudadas foram granulometria, densidade e teor de umidade. Ap?s definirem-se os par?metros ?timos, avaliou-se o efeito do processamento da ervamate em tr?s diferentes etapas na melhor condi??o: fresca, sapecada e cancheada. Quanto ?s condi??es de opera??o, avaliou-se a influ?ncia da porosidade e do teor de cossolvente (etanol) durante o processo de extra??o, com a press?o e a temperatura de opera??o sendo fixadas em valores ?timos para a remo??o de cafe?na. Ainda, verificou-se o efeito da raz?o massa de planta/massa de solvente utilizado. Os extratos foram analisados por cromatografia l?quida de alta efici?ncia. Como resultado deste estudo observou-se que o aumento do teor de umidade presente na planta favoreceu a remo??o de cafe?na, atingindo uma concentra??o final de 0,30% de cafe?na (g/100g), enquanto que a utiliza??o de etanol como cossolvente durante o processo de extra??o resultou em uma concentra??o final de 0,03% (g/100g) de cafe?na. Para o processamento, a amostra sapecada apresentou os melhores resultados, tanto em rela??o ao rendimento de extrato obtido como em rela??o ? remo??o de cafe?na. Quanto ? atividade biol?gica do produto descafeinado, verificou-se que as infus?es de erva-mate diminuem a viabilidade celular de diferentes linhagens celulares de c?ncer de es?fago e que este efeito ? independente da concentra??o de cafe?na na planta. Por fim, procedeu-se a modelagem matem?tica da curva de extra??o a fim de correlacionar as vari?veis de processo com os dados experimentais.
2

Projeto de engenharia do processo de extra??o supercr?tica de cafe?na da erva mate / Process study of caffeine supercritical extraction from yerba mate

Petersen, Helena de Souza 27 March 2017 (has links)
Submitted by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-06-30T17:34:35Z No. of bitstreams: 1 DIS_HELENA_DE_SOUZA_PETERSEN_COMPLETO.pdf: 655908 bytes, checksum: 7c6cf0da861a822fa2beba34ea724e4b (MD5) / Made available in DSpace on 2017-06-30T17:34:35Z (GMT). No. of bitstreams: 1 DIS_HELENA_DE_SOUZA_PETERSEN_COMPLETO.pdf: 655908 bytes, checksum: 7c6cf0da861a822fa2beba34ea724e4b (MD5) Previous issue date: 2017-03-27 / The supercritical extraction emerged at the last decades as a green technology and as an alternative process to produce natural products and food. The process of supercritical extraction, using CO2 as a solvent, has been extensively studied, but there are fewer works about scale-up. Therefore, this work proposes to study the industrial supercritical fluid extraction of caffeine from yerba mate to produce decaffeinated yerba mate, an innovative product in the market, and caffeine, a product that has equal or even more value in the market than the main product. Design basis of this work are the experimental results of supercritical extraction in pilot scale and the appliance of a scale-up method based on the maintenance of the solvent mass flow and the raw-material mass flow proportion. Thus, process data sheet of main equipment were generated: extraction vessel, heat exchanger and high pressure pump. The maximum daily caffeine extraction capacity was estimated at two tons and the solvent mass flow rate of 22 t/h was obtained from the equation residence time of the solvent, maintaining constant the porosity of the 0.79 bed obtained in scale pilot. In addition, a process flow diagram was proposed for an industrial scale plant supercritical extraction of caffeine from yerba mate. / A extra??o supercr?tica emergiu nas ?ltimas d?cadas como uma tecnologia verde promissora e uma alternativa para o processamento de alimentos e produtos naturais. O processo de extra??o supercr?tica, utilizando CO2 como solvente, vem sendo extensivamente estudado, mas poucos ainda s?o os trabalhos que visam o escalonamento do processo. Logo, este trabalho prop?e estudar o processo industrial de extra??o supercr?tica de cafe?na a partir da erva-mate, que tem como meta produzir erva-mate descafe?nada, produto inovador no mercado, e cafe?na, um subproduto t?o ou mais valorizado que o produto principal. A base de c?lculo s?o os experimentos realizados em escala piloto e a utiliza??o de m?todo de aumento de escala que prop?e a manuten??o de propor??o de massa de solvente e massa de mat?ria-prima. Sendo assim, foram geradas folhas de dados de processo para os principais equipamentos: vaso extrator, trocadores de calor e bomba de alta press?o. A capacidade di?ria m?xima de extra??o de cafe?na foi prevista em duas toneladas e a vaz?o m?ssica de solvente de 22 toneladas/hora foi obtida a partir do equacionamento de tempo de resid?ncia do solvente, mantendo constante a porosidade do leito de 0,79 obtida em escala piloto. Al?m disto, foi proposto um fluxograma para uma planta em escala industrial de extra??o supercr?tica da cafe?na a partir da erva mate.

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