Biblioteca do Café
URI permanente desta comunidadehttps://thoth.dti.ufv.br/handle/123456789/1
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Resultados da Pesquisa
Item Evaluation of the behavior of coffee stored in cooled and natural environments(Universidade Federal de Lavras, 2023-01-11) Andrade, Ednilton Tavares de; Rezende, Renan Pereira; Borém, Flávio Meira; Rosa, Sttela Dellyzete Veiga Franco da; Rios, Paula de Almeida; Oliveira, Filipe da Silva deThe market value of coffee is strongly influenced by loss of quality, which makes storage one of the main steps in the entire production chain. The finite element method (FEM) and computational fluid dynamics (CFD) are numerical and computational techniques that facilitate the simulation of agricultural product storage systems. Computational modeling satisfactorily represents real experimentation, simplifies decision-making, and reduces costs. This study aimed to analyze mocha coffee storage for 6 months in a cooled environment with temperatures between 15 and 18 °C and in a natural environment. The water content, bulk density, specific heat, thermal conductivity, and thermal diffusivity were determined and colorimetry and sensory analysis were applied to compare initial and final samples of the product after storage. It was found that the water content and specific heat were the only properties that presented significant changes. Through sensory analysis, it was observed that the quality of the coffee was the same for both systems. A computational model was developed to simulate the heat transfer process during storage. The comparison of the simulation results with the experimental results for the temperature distribution in the grain mass showed overall mean relative errors of 2.34% for the natural environment and 5.74% for the cooled environment.Item Origin of black-green defect in the artificial drying of immature coffees(Editora UFLA, 2021) Rios, Paula de Almeida; Andrade, Ednilton Tavares de; Cardoso, Danilo BarbosaThe inequality of coffee maturation leads to a large portion of green berries in the harvest. Post-harvest management techniques seek to minimize defects during the drying process, such as black-green defects in harvested immature berries. The present study aimed to investigate the minimum occurrence of black-green defects in the drying of immature coffee berries subjected to different temperature conditions and relative humidity values. In addition to fitting mathematical models to the experimental data, the effective diffusion coefficient and the water reduction rate (WRR) were determined. Nine coffee crops (Coffea arabica L.) of the Topázio Amarelo variety were harvested manually and selectively during the green maturation stage, with an initial water content of 2.106 ± 0.05 kg.kg-1 (dry basis, d.b.). After drying, the coffee was subjected to a drying treatment in a fixed-layer dryer with combined dry bulb temperatures (Dbt) of 35, 40 and 45 °C and dew point temperatures (Dpt) of 2.6, 10.8 and 16.2 °C until a final water content of 0.124 ± 0.05 kg.kg-1 (db) was reached. After drying, black-green defects were quantified as percentages. In addition to the drying kinetics, the WRR and effective diffusivity were evaluated. The lowest percentage of black-green defects occurred at a temperature of 35 °C and a Dpt of 2.6 °C (11.00%), which is the most suitable treatment for drying natural green coffees. The highest percentage of defects occurred when a Dbt of 35 °C was combined with a Dpt of 16.2 °C (14.17%). This combination showed the lowest effective diffusion coefficient of 0.551 x 10-11 m2.s-1. The Midilli model had the best fit to the experimental data for all drying combinations. The lowest WRR was 0.063 kg.kg-1.h-1 and was observed when a Dbt of 35 °C was combined with a Dpt of 16.2 °C.Item Mathematical modeling of dehydration resistance of pericarp tissues and endosperm in fruits of arabic coffee(Editora UFLA, 2020) Dias, Camila de Almeida; Andrade, Ednilton Tavares de; Lemos, Isabella Àvila; Borém, Flávio Meira; Westerich, Diogo Nogueira; Silva, Ana Claudia Almeida daCoffee represents an important source of income for producers and for the Brazilian economy, being the second product in the country’s agricultural exports. Unlike other agricultural products, freshly harvested coffee has a high fruit water content, approximately 60% (dry base). It is fundamental to optimize the drying process for cost reduction and quality maintenance, making it necessary to understand the interdependence relation of the tissues of the pericarp and the coffee endosperm during the dehydration of the fruit. The objective of this work was to elaborate a drying model for the constituent parts of coffee fruits evaluating the resistance of each of the pericarp tissues and endosperm. The experiment was set up in a 4x6 factorial scheme (4 relative humidity of the drying air and natural, pulped natural coffee, pericarp tissues and endosperm: 1 - natural coffee and 2 – pulped natural coffee, 3 - exocarp + a portion of mesocarp, 4 - mesocarp, 5 - endocarp, 6 - endosperm]) in a completely randomized design with four replicates. The results were analyzed through analysis of variance and regression, using the statistical software STATISTICA 5.0®. The resistance to water outflow, regardless of the processing or the fruit part of the coffee, is greater when the coffee is dried with the lowest relative humidity. The natural coffee was the treatment that presented greater resistance, while the lower resistance was presented by the exocarp + a portion of mesocarp.Item Determination of thermal properties of coffee beans at different degrees of roasting(Editora UFLA, 2018-10) Cardoso, Danilo Barbosa; Andrade, Ednilton Tavares de; Calderón, Renso Alfredo Aragón; Rabelo, Mariane Helena Sanches; Dias, Camila de Almeida; Lemos, Isabela ÁvilaThe aim in this study was to determine the main thermal properties of the granular mass of coffee (specific heat, thermal conductivity, and thermal diffusivity) for different degrees of roasting, as well as to model and simulate thermal conductivity at different degrees of roasting. For determination of specific heat, the mixing method was used, and for thermal conductivity, the theoretically infinite cylinder method with a central heating source. Thermal diffusivity was simulated algebraically using the results of the properties cited above and of the apparent specific mass of the product. Thermal conductivity was also simulated and optimized through finite element analysis software. As results, at darker roasting there was an increase in specific heat and a reduction in thermal conductivity and thermal diffusivity. Comparing thermal conductivity determined in relation to simulated and optimized conductivity, the mean relative error was 1.02%, on average.Item Simulation of coffee fruit drying using computational fluid dynamics(Editora UFLA, 2018-10) Amaral, Rudney; Andrade, Ednilton Tavares de; Gomes, Francisco Carlos; Borém, Flávio Meira; Lemos, Isabela Avila; Dias, Camila de AlmeidaDrying is a fundamental step in post-harvest handling of coffee because moisture content at the end of drying affects several important aspects, such as sensory quality, storability, and color of the fruit coffee. Within this context, the aim of this study is to determine water distribution within the natural coffee fruit during and at the end of the drying process. For that purpose, simulations were made through finite elements using computational fluid dynamics. Experimental data on moisture content of coffee fruit in the “cherry” stage were collected during drying, which was carried out at a temperature of 40°C and relative humidity of 25% to 0.18 decimal l(dry basis – d.b.) to compare the results of the experiment with the results of the simulations. Ten mathematical models of the drying process were developed for the collected data. The two-term exponential model best fit the data. The results of the simulations in computational fluid dynamics were compared to the results from experimental drying, and a satisfactory fit was obtained. The effective diffusivity coefficient (D eff ) was developed for the model proposed, obtaining the value of 2.87 x 10 ‐11 m 2 s -1 . At the end of drying, the model exhibited 57.1% of the projection area of the coffee fruit with moisture content below 0.18 decimal (d.b.). Thus, the model can be used for other applications.Item Efeito do impacto mecânico induzido sobre a integridade dos grãos e a qualidade do café(2003) Afonso, Paulo César; Corrêa, Paulo César; Andrade, Ednilton Tavares de; Consórcio Brasileiro de Pesquisa e Desenvolvimento do CaféEste trabalho foi desenvolvido com o objetivo de avaliar os efeitos do dano mecânico provocado por um único impacto em diferentes velocidades e em posição aleatória, e de danos mecânicos provocados por impactos múltiplos, sobre a integridade dos grãos e qualidade do café de diferentes cultivares armazenados pelo período de seis meses. Para todos os tratamentos e a cada dois meses foram realizadas, como indicativos da qualidade do produto, avaliações de condutividade elétrica da solução de embebição e da cor dos grãos beneficiados de café. Com base nos resultados obtidos dos testes experimentais concluiu-se que o impacto mecânico nos grãos de café favoreceu a redução da qualidade do produto, tanto do cultivar Catuaí quanto do cultivar Conilon; e ainda, que os grãos de café levam consigo algum efeito latente da danificação por impactos mecânicos sobre a qualidade destes. O efeito de danificação sobre o café pode sofrer uma redução, diminuindo-se a velocidade e o número de impactos nos grãos, para que se retarde o início do processo degenerativo do produto e, por fim, que os fatores que causam redução da qualidade do café aparecem com maior amplitude nos grãos submetidos a inúmeros impactos e a velocidades mais elevadas.Item Composição química de grãos de cafés (Coffea arabica L.), submetidos a diferentes tipos de pré processamento(2001) Pereira, Rosemary Gualberto Fonseca Alvarenga; Villela, Tulio Carvalho; Andrade, Ednilton Tavares de; Consórcio Brasileiro de Pesquisa e Desenvolvimento do CaféO presente trabalho teve por objetivo investigar a existência de diferenças na composição química de cafés submetidos a diferentes etapas de processamento no município de Espírito Santo do Pinhal. Cafés da cultivar Mundo Novo cultivadas sob as mesmas condições de campo foram submetidos a cinco tipos de processamentos: 1-cereja descascado desmucilado, 2-café cereja, 3-café bóia, 4-semi-desmucilado e 5-cereja descascado. Os tratamentos foram analisados e comparados pelo teste de Tukey a 5% de probabilidade. Foram feitas as seguintes análises químicas: avaliação dos teores de açúcares totais, redutores e não-redutores, sólidos solúveis totais e condutividade elétrica. As análises químicas foram realizadas no Laboratório de Grãos e Cereais do Departamento de Ciência dos Alimentos da Universidade Federal de Lavras. Diferenças significativas foram constatadas para as variáveis açúcares redutores, condutividade elétrica dos grãos e sólidos solúveis. Não houve diferença significativa entre os tratamentos para as variáveis açúcares totais e não-redutores. O café cereja apresentou a maior concentração de açúcares redutores e o café descascado desmucilado, o menor valor. O café cereja descascado apresentou valor estatisticamente superior ao dos demais tratamentos, que não diferiram entre si. A condutividade elétrica variou significativamente entre os tipos de pré-processamento, destacando-se o café cereja e o café bóia, com os maiores e menores valores, respectivamente.Item Efeito de diferentes graus de maturação do café (Coffea arabica L.) e diferentes temperaturas de secagem na qualidade(2001) Oliveira, Gilvana Aparecida de; Vilela, Evódio Ribeiro; Borém, Flávio Meira; Pereira, Rosemary Gualberto Fonseca Alvarenga; Andrade, Ednilton Tavares de; Consórcio Brasileiro de Pesquisa e Desenvolvimento do CaféOs objetivos desta pesquisa foram estudar, física e quimicamente, a qualidade do café com diferentes graus de maturação e secos em diferentes temperaturas. O trabalho foi realizado nos Departamentos de Ciência dos Alimentos e de Agricultura da Universidade Federal de Lavras e na Empresa de Pesquisa Agropecuária de Minas Gerais (EPAMIG). Foram utilizados cafés cereja, bóia/seco e mistura (derriça no pano) como matéria-prima para secagem e armazenamento. A secagem foi feita em terreiro e em secador experimental de camada fixa, utilizando temperaturas, na massa de café, de 45° C, 50° C e 55° C para cada estádio de maturação. O café foi armazenado em sacos de aniagem por seis meses, em condições ambientais, com monitoramento das condições de temperatura e umidade relativa do ar. As análises (classificação por tipo e bebida, umidade, índice de coloração e atividade enzimática da polifenoloxidase) foram realizadas nos meses de setembro/1999, novembro/1999, janeiro/2000 e março/2000. Pelos resultados obtidos, concluímos que a prova de xícara é um pouco subjetiva, pois todas as amostras se classificaram como bebida dura. Todas as análises feitas tiveram diferenças significativas entre as amostras de café bóia, cereja e mistura, com melhores resultados, de modo geral, para a secagem em terreiro, para a secagem em secador utilizando temperaturas de 45°C e 50° C e para o café cereja.