Extração de cafeina, trigonelina e acido clorogenico dos grãaos de cafe com CO2 supercritico
Marleny Doris Aranda Saldana
DISSERTAÇÃO
Português
T/UNICAMP Ar14e
Campinas, SP : [s.n.], 1997.
186f. : il.
Orientador: Rahoma Sadeg Mohamed.
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
Resumo: Alguns compostos químicos encontrados em plantas possuem ação sobre o organismo humano. Dentre as muitas substâncias encontradas nos grãos de café, chá mate, guaraná e cacau, a cafeína é de grande importância devido a seu efeito estimulante e diurético no organismo humano. Este alcalóide...
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Resumo: Alguns compostos químicos encontrados em plantas possuem ação sobre o organismo humano. Dentre as muitas substâncias encontradas nos grãos de café, chá mate, guaraná e cacau, a cafeína é de grande importância devido a seu efeito estimulante e diurético no organismo humano. Este alcalóide purínico em doses moderadas diminui a fadiga, enquanto que em altas concentrações atua no sistema nervoso central, podendo ser letal. Por isso, consumidores de idade avançada e pessoas sensíveis são aconselhados a evitar o consumo de café. A trigonelina, outro alcalóide encontrado nos grãos de café, também atua no sistema nervoso central. Este princípio ativo, juntamente com os produtos provenientes de sua degradação térmica, possuem importância nutricional: formação da vitamina B3 (niacina). A formação de complexos de ácido clorogênico (CGA) com a cafeína está associado a propriedades sensoriais, levando a hipóteses de que o CGA tem um papel importante na qualidade do café. Porém, uma concentração elevada de CGA no grão ocasiona um sabor amargo e adstringente; portanto, sua análise e remoção nos grãos verdes e descafeinados seriam importantes para a obtenção de um produto de interesse comercial. O mercado do café descafeinado e da cafeína é potencialmente grande e vem crescendo. A cafeína, vendida para indústrias de refrigerantes e farmacêuticas, geralmente cobra os custos do processo. A demanda de café descafeinado é grande nos países industrializados. A qualidade do café descafeinado, assim como seus efeitos no metabolismo humano, justificam seu êxito. O CO2 vem-se apresentando como o solvente mais adequado devido a sua atoxicidade, não flamabilidade, baixa temperatura crítica, não poluir o meio ambiente e de baixo custo. O presente trabalho tem por objetivo levantar subsídios experimentais e teóricos que permitam compreender e avaliar a extração supercrítica como uma tecnologia de remoção de alcalóides (cafeína e trigonelina) e ácido clorogênico explorando o uso de fluidos supercríticos na remoção e fracionamento dos grãos de café. Foram determinadas as solubilidades da cafeína pura e as quantidades de cafeína, trigonelina e ácido clorogênico nos grãos de café Robusta, espécie canephora, no CO2 supercrítico a 313, 323 e 343 K, e pressões variando de 9,5 a 23,5 MPa, utilizando um aparelho experimental a altas pressões, que permite um controle independente das variáveis termodinâmicas de temperatura e pressão. Os resultados revelam a existência de um comportamento retrógrado para a solubilidade da cafeína pura e a obtida dos grãos de café no CO2 supercrítico. Este mostra uma alta seletividade pela cafeína em comparação à trigonelina e ao ácido clorogênico. Observaram-se maiores teores de cafeína, trigonelina e ácido clorogênico com os grãos partidos e moídos quando comparados aos inteiros, mostrando a influência do tamanho e da estrutura dos grãos de café no processo de extração. As análises de cafeína, trigonelina e ácido clorogênico foram realizadas por Cromatografia Líquida de Alta Eficiência (HPLC). Um modelo termodinâmico baseado no equilíbrio sólido/fluido supercrítico, considerando a fase supercrítica como um gás comprimido e utilizando uma equação de estado de quarta ordem, apresentou bons resultados para as solubilidades da cafeína pura no CO2 supercrítico. Espera-se que este trabalho possa contribuir tanto para o desenvolvimento tecnológico, quanto para o fornecimento de subsídios que permitam um melhor controle do processo para a remoção da cafeína, trigonelina e ácido clorogênico e para o fracionamento dos materiais extraíveis com CO2 supercrítico
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Abstract: Some chemical compounds found in plant extracts have important effects in the human organism. Among the many substances found in coffee beans, tea, guaraná and cocoa, caffeine has a major importance because of its stimulant and diuretic effects in the human organism. This purinic alkaloid...
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Abstract: Some chemical compounds found in plant extracts have important effects in the human organism. Among the many substances found in coffee beans, tea, guaraná and cocoa, caffeine has a major importance because of its stimulant and diuretic effects in the human organism. This purinic alkaloid stimulates the central nervous system, acts on the circular and muscle system and has little effect on the digestive tube. While in small quantities caffeine decreases fatigue, a high concentration can affect the rins, liver and nervous system, being harmful in overdoses. Because of its stimulant effect, consumers of advanced age and sensitive people are advised to avoid coffee consumption.
Trigonelline, another alkaloid found in coffee beans, also acts on the nervous central system. This active substance together with the products of its thermal degradation have nutritional importance: formation of vitamin B3 ('niacin'). Some chlorogenic acid (CGA) isomers and caffeine complexes are associated with coffee sensorial properties, leading to the widely accepted belief that o CGA has an important role in determining the quality and price of the coffee. A high CGA concentration in the beans produce a bitter and astringent flavor. For this reason the removal of CGA in green and decaffeinated beans is an important parameter in obtaining a product of commercial quality. The market of decaffeinated coffee and caffeine is potentially big and fast growing. Caffeine sold to cola soft drinks and pharmaceutical industries normally covers the decaffeinated process costs. Demand for decaffeinated coffee comes mainly ITom industrialized countries. The quality of decaffeinated coffee and its positive effects in the human metabolism are the main reasons for its acceptance and success. Carbon dioxide is probably the most adequate solvent because of its distinct characteristics, being non toxic, inflamable, non polluent, inexpensive and having low critical temperature. The objective of this work was to obtain experimental data that can contribute to a better understanding and evaluation of supercritical extraction as a viable technology for the removal of alkaloids (caffeine and trigonelline) and chlorogenic acid. The solubilities of caffeine and extractable materials from Robusta coffee beans, type canephora, in supercritical CO2 were determined at 313, 323 and 343 K, and pressures ranging from 9,5 to 23,5 MPa, using a high pressure experimental apparatus, that allows the independent control of all thermodynamic variables of temperature and pressure. Results revealed a retrograde behavior for the solubilities of pure caffeine and that obtained ITom coffee beans in supercritical CO2. Supercritical carbon dioxide showed a high selectivity for caffeine in comparison to trigonelline and chlorogenic acid. Higher concentrations of caffeine, trigonelline and chlorogenic acid were obtained with flaked and ground beans when compared to those obtained with whole coffee beans, demonstrating the influence of size and structure of coffee beans on the extraction process. In this work, caffeine, trigonelline and chlorogenic acid were identified and quantified by high performance liquid chromatography (HPLC). A thermodynamic model for the solid/supercritical fluid equilibrium, which considers the supercritical phase a compressed gas and uses a quartic equation of state to describe the volumetric behavior of the mixture was successfully employed to correlate the solubility of pure caffeine in supercritical CO2. It is hoped that this work can contribute to the development of an alternative technology for the removal of caffeine, trigonelline and chlorogenic acid and the fractionation of extractable materials using supercritical CO2 Ver menos
Trigonelline, another alkaloid found in coffee beans, also acts on the nervous central system. This active substance together with the products of its thermal degradation have nutritional importance: formation of vitamin B3 ('niacin'). Some chlorogenic acid (CGA) isomers and caffeine complexes are associated with coffee sensorial properties, leading to the widely accepted belief that o CGA has an important role in determining the quality and price of the coffee. A high CGA concentration in the beans produce a bitter and astringent flavor. For this reason the removal of CGA in green and decaffeinated beans is an important parameter in obtaining a product of commercial quality. The market of decaffeinated coffee and caffeine is potentially big and fast growing. Caffeine sold to cola soft drinks and pharmaceutical industries normally covers the decaffeinated process costs. Demand for decaffeinated coffee comes mainly ITom industrialized countries. The quality of decaffeinated coffee and its positive effects in the human metabolism are the main reasons for its acceptance and success. Carbon dioxide is probably the most adequate solvent because of its distinct characteristics, being non toxic, inflamable, non polluent, inexpensive and having low critical temperature. The objective of this work was to obtain experimental data that can contribute to a better understanding and evaluation of supercritical extraction as a viable technology for the removal of alkaloids (caffeine and trigonelline) and chlorogenic acid. The solubilities of caffeine and extractable materials from Robusta coffee beans, type canephora, in supercritical CO2 were determined at 313, 323 and 343 K, and pressures ranging from 9,5 to 23,5 MPa, using a high pressure experimental apparatus, that allows the independent control of all thermodynamic variables of temperature and pressure. Results revealed a retrograde behavior for the solubilities of pure caffeine and that obtained ITom coffee beans in supercritical CO2. Supercritical carbon dioxide showed a high selectivity for caffeine in comparison to trigonelline and chlorogenic acid. Higher concentrations of caffeine, trigonelline and chlorogenic acid were obtained with flaked and ground beans when compared to those obtained with whole coffee beans, demonstrating the influence of size and structure of coffee beans on the extraction process. In this work, caffeine, trigonelline and chlorogenic acid were identified and quantified by high performance liquid chromatography (HPLC). A thermodynamic model for the solid/supercritical fluid equilibrium, which considers the supercritical phase a compressed gas and uses a quartic equation of state to describe the volumetric behavior of the mixture was successfully employed to correlate the solubility of pure caffeine in supercritical CO2. It is hoped that this work can contribute to the development of an alternative technology for the removal of caffeine, trigonelline and chlorogenic acid and the fractionation of extractable materials using supercritical CO2 Ver menos
Extração de cafeina, trigonelina e acido clorogenico dos grãaos de cafe com CO2 supercritico
Marleny Doris Aranda Saldana
Extração de cafeina, trigonelina e acido clorogenico dos grãaos de cafe com CO2 supercritico
Marleny Doris Aranda Saldana
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