Preparação e caracterização de carvão ativado produzido a partir de resíduos do beneficiamento do café

Coffee fruit processing is one of the most polluting activities in agriculture due to the large amount of waste generated in the process. In this work, coffee parchment was employed as precursor for the production of carbons activated with ZnCl2 (CAP). The material was characterized using N2 adsorption/desorption at 77 K, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The material showed a surface area of 521.6 m²g-1 and microporous structure. CAP was applied as adsorbent for the removal of methylene blue dye in aqueous medium. The adsorption capacity was found to be about 188.7 mg g-1.

Preparação de carvão ativado em baixas temperaturas de carbonização a partir de rejeitos de café: utilização de FeCl3 como agente ativante

Ferric chloride as a new activating agent was used to obtain activated carbons from agroindustrial waste. This material was prepared at three temperatures of pyrolysis, 200, 280 and 400 ºC. The carbonaceous materials obtained after the activation processes showed high specific surface areas (BET), with values higher than 900 m² g-1. The materials showed different behaviors in the adsorption of methylene blue dye and reactive red textile dye in water solutions. An important fact in the use of FeCl3 as an activating agent is that the activation temperature is at 280 ºC, well below of those commonly employed in chemical or physical activations described in the literature.

Materiais à base de óxido de ferro para oxidação de compostos presentes no efluente da despolpa do café

Materials based on pure iron oxide and impregnated with niobia (Nb2O5) were prepared. Their catalytic activities were tested on the oxidation of compounds present in the wastewater from the processing of coffee berries. Particularly caffeine and catechol were tested. The oxidation reactions were carried out with the following systems (i) UV/H2O2, (ii) photo-Fenton and (iii) heterogeneous Fenton. All materials were characterized with X-ray diffraction, Mössbauer and infrared spectroscopy. Iron was mainly in the forms of goethite and maghemite. The oxidation kinetics were monitored by UV-vis and the oxidation products were monitored by mass spectrometry. The photo-Fenton reaction presented highest oxidation efficiency, removing 98% of all caffeine and catechol contents.

Composição volátil dos defeitos intrínsecos do café por CG/EM-headspace

About 20% of Brazilian raw coffee production is considered inappropriate for exportation. Consequently, these beans are incorporated to good quality beans in the Brazilian market. This by-product of coffee industry is called PVA due to the presence of black (P), green (V) and sour (A) defective beans which are known to contribute considerably for cup quality decrease. Data on the volatile composition of Brazilian defective coffee beans are scarce. In this study, we evaluated the volatile composition of immature, black-immature, black defective beans and PVA compared to good quality beans. Potential defective beans markers were identified.

Compostos bioativos e atividade antioxidante do café conilon submetido a diferentes graus de torra

The bioactive compounds and antioxidant activity presented by Conilon coffee (C. Canephora) variety, produced in the Espírito Santo State, Brazil, were quantified. The light roast coffee showed the highest level of total phenols, trigonelline, caffeic and chlorogenic acids. The proanthocyanidin level was the highest for dark roast coffee, while caffeine level didn't show significative changes for the light and middle roast coffees. All the Conilon coffee extracts showed antioxidant activity depending on bioactive compounds concentration and roasting degree. The coffee samples submitted to a light roasting degree showed the highest antioxidant activity.

Produção e caracterização de carvão ativado produzido a partir do defeito preto, verde, ardido (PVA) do café

The black, green and sour coffee defect (PVA) contributes with 20% of the total coffee production. It should be separate from the normal coffee grains in order to improve the final quality of the beverage. In this way, the present work has the objective to use the PVA reject for the production of activated carbon. The activated carbon (CA) was prepared from PVA defect using zinc chloride as activating agent. The prepared material (CA PVA) was characterized and the adsorption tests were carried out using as organic models methylene blue (AM) and reactive red (VR). The CA PVA revealed to be more efficient in the removal of the organic contaminants compared to a commercial activated carbon.

Benefícios do café na saúde: mito ou realidade?

Coffee is widely consumed and appreciated all over the world, both for their stimulating effect and organoleptic characteristics. Due to its complex chemical composition and the factors involving brews preparation, the consumer is exposed to a wide range of chemical compounds. Several investigations aimed to clarify and understand coffee health effects. There is no evidence that moderate consumption could be harmful. On the contrary, some benefits and possible protective effects against several pathologies have been suggested. This review compiles the main conclusions related with the "coffee and health" topic, reporting, when possible, the chemicals involved.

Compostos bioativos do café: atividade antioxidante in vitro do café verde e torrado antes e após a descafeinação

This study aimed to evaluate the effect of coffee decaffeination with dichloromethane on the in vitro antioxidant activity of this matrix. It were determined the content of total phenolics, chlorogenic acid and caffeine of the coffee samples. The assessment of the antioxidant potential was investigated by DPPH radical scavenging method, reducer power and Fe2+chelation activity. The process of decaffeination and roasting caused changes in the levels of the compounds investigated. The results show that the decaffeination by the dichloromethane method reduces the in vitro antioxidant potential of coffee.

Determinação simultânea de precursores de serotonina - triptofano e 5-hidroxitriptofano - em café

Epidemiological studies attributed positive effects in the central nervous system (CNS) to coffee. Among possible active constituents, serotonin, a neurotransmitter in the CNS, is present; but dietary sources do not cross the blood-brain barrier. Tryptophan and 5-hidroxytryptophan (5-HTP) are serotonin precursors and can affect brain concentrations. An ion-pair-HPLC, post-column derivatization with o-phthalaldehyde and fluorimetric detection before and after hydrolysis with NaOH and extraction with methanol:water was developed for the simultaneous determination of these compounds. It was selective, sensitive (LOD = 0.3 and 0.2 μg/mL), precise (91.3 and 94.2% recovery for tryptophan and 5-HTP, respectively), and linear from 0.3 to 40 μg/mL for both compounds. It was applied to green and roasted arabica and robusta coffees.

Método para determinação de carboidratos empregado na triagem de adulterações em café

The objective in this work was to validate a chromatography method for the determination of total carbohydrates in soluble coffee, using a HPLC-UV-VIS with postcolumn derivatization system, in order to verify adulterant additions. The validated method was accurate and robust. Adulteration could be observed by increasing xylose and glucose levels in samples with addition of coffee husks and starchy products while decreasing of galactose and mannose characteristic carbohydrates presenting in high concentration in soluble coffees produced by arabica and robusta coffee beans.

Espectroscopia no infravermelho médio e análise sensorial aplicada à detecção de adulteração de café torrado por adição de cascas de café

Mid-infrared spectroscopy and chemometrics were used to identify adulteration in roasted and ground coffee by addition of coffee husks. Consumers' sensory perception of the adulteration was evaluated by a triangular test of the coffee beverages. Samples containing above 0.5% of coffee husks from pure coffees were discriminated by principal component analysis of the infrared spectra. A partial least-squares regression estimated the husk content in samples and presented a root-mean-square error for prediction of 2.0%. The triangular test indicated that were than 10% of coffee husks are required to cause alterations in consumer perception about adulterated beverages.

Correlação entre precursores e voláteis em café arábica brasileiro processado pelas vias seca, semiúmida e úmida e discriminação através da análise por componentes principais

The influence of pre-processing of arabica coffee beans on the composition of volatile precursors including sugars, chlorogenic acids, phenolics, proteins, aminoacids, trigonelline and fatty acids was assessed and correlated with volatiles formed during roasting. Reducing sugars and free aminoacids were highest for natural coffees whereas total sugars, chlorogenic acids and trigonelline were highest for washed coffees. The highest correlation was observed for total phenolics and volatile phenolics (R= 0.999). Experimental data were evaluated by Principal Components Analysis and results showed that washed coffees formed a distinct group in relation to semi-washed and natural coffees.

Fungicidas aplicados via água de irrigação no controle do mofo-branco no feijoeiro e incidência do patógeno na semente

Foi instalado um experimento em Viçosa, MG, em 11 de abril, em área infestada por escleródios de Sclerotinia sclerotiorum, com o objetivo de testar a eficiência de quatro fungicidas aplicados via água de irrigação por aspersão no controle do mofo-branco do feijoeiro (Phaseolus vulgaris). Os seguintes fungicidas e doses do ingrediente ativo por hectare foram testados: benomyl (1 kg), iprodione (0,75 kg), procimidone (0,5 kg) e fluazinam (0,5 l). As aplicações foram simuladas com regadores (35.000 l/ha). A primeira aplicação foi feita aos 39 dias após a emergência (DAE); a segunda, 13 dias depois. Nesses mesmos dias, o fluazinam também foi aplicado com pulverizador (667 l/ha) ou com regador (35.000 l/ha) entre as fileiras de feijão e rente ao solo. Este último tratamento teve por objetivo verificar se o fluazinam aplicado apenas no solo tem efeito no controle da doença. Ademais, foi utilizada uma testemunha que não recebeu fungicida. Após a colheita, avaliou-se a incidência do fungo nas sementes. Os fungicidas fluazinam (aplicado com pulverizador ou via água de irrigação sobre as plantas), benomyl e procimidone foram os mais eficientes no controle do mofo-branco e, dentre eles, apenas o procimidone não proporcionou rendimento maior que o da testemunha. O fluazinam aplicado apenas no solo reduziu a incidência da doença e a quantidade de escleródios produzidos. Os rendimentos variaram de 1.406 (testemunha) a 2.054 kg/ha (fluazinam, pulverização). Não houve influência dos tratamentos na incidência do fungo nas sementes, a qual variou de 0,25% (procimidone) a 1,08% (fluazinam aplicado no solo).

Manejo do solo e da irrigação como nova tática de controle de Meloidogyne incognita em feijoeiro

A população de Meloidogyne incognita e sua infetividade foram estudadas em parcelas amostradas a zero, dois e 14 dias após o revolvimento do solo com ou sem irrigação, irrigadas sem revolvimento e testemunha. Na amostragem aos dois dias após a instalação do ensaio, ocorreu maior redução (P<0,01) de juvenis do segundo estádio ( J2) no solo apenas revolvido seguido pelo revolvido e irrigado. A infetividade do inóculo do solo, contudo, foi menor (P<0,01) quando se revolveu e irrigou o solo comparado com aquele apenas revolvido. Aos 14 dias, a menor (P<0,01) população de J2 foi observada no solo revolvido e irrigado, seguido do revolvido, e elevada naquele apenas irrigado e na testemunha. A infetividade do inóculo do solo aos 14 dias continuou mais baixa no solo revolvido e irrigado. Aos 45 dias após a semeadura, a população de J2 continuou mais baixa (P<0,01) onde o solo foi revolvido e irrigado. O número de ovos por feijoeiro (Phaseolus vulgaris) no campo aos 90 dias também foi mais baixo (P<0,01) no solo revolvido e irrigado. Maior (P<0,01) peso das raízes e da parte aérea dos feijoeiros no campo foi observado em plantas crescidas em solo apenas revolvido, e no revolvido e irrigado A produção de feijão no solo revolvido e irrigado posteriormente foi quatro vezes maior que a testemunha, porém todos os tratamentos diferiram-se entre si. A irrigação como prática agrícola para aumentar a eficácia do alqueive no controle de fitonematóides tem sido postulada por alguns pesquisadores, mas nunca provada experimentalmente, o que agora foi realizada.

Intensidade do mofo-branco do feijoeiro em plantio convencional e direto sob diferentes lâminas d'água

Utilizando-se de um gradiente de lâminas d'água obtidas com o sistema de irrigação por aspersão em linha "line source" e duas cultivares de feijoeiro (Phaseolus vulgaris), sob os sistemas de plantio direto e convencional, verificou-se aumento da intensidade do mofo-branco causado por Sclerotinia sclerotiorum e da produção de escleródios com o incremento da lâmina d'água. Com inóculo inicial de 0,2 escleródio/kg de solo a porcentagem de plantas infetadas variou de 0 a 100% em 1998 e de 0 a 12% em 1999. Maior severidade e incidência do mofo-branco ocorreram na cultivar de porte prostrado, em cultivo convencional. Em ambos os anos, a intensidade da doença, a produção de escleródios e a formação de apotécios foram menores no sistema de plantio direto do que no convencional. Finalmente, em ambos os experimentos foi detectado cerca de quatro vezes mais escleródios no resíduo da trilhadora no plantio convencional que no plantio direto, mostrando que a produção de inóculo para as safras subseqüentes no plantio convencional é muito maior que no direto. Este é um fato relevante, considerando-se a importância do inóculo inicial para as doenças monocíclicas, como é o caso do mofo-branco do feijoeiro, e tem implicações diretas na sustentabilidade do sistema de produção irrigado de inverno.