Coffee Science
URI permanente desta comunidadehttps://thoth.dti.ufv.br/handle/123456789/3355
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Item Modeling effectiveness analysis of momentum and heat transfer in a fixed bed silo-dryer through computational fluid-dynamics(Editora UFLA, 2021) Mateus, Felipe Leonardo Barcelos; Petri Júnior, IrineuThe drying procedure is of great use in the industry, being capable of increasing the shelf life of many products, in addition to facilitate its transport and storage. The operation is essential for coffee beans to remove their excessive moisture content. The silo-drier has potential to ensure sensorial qualities through the intermittent drying, as well as with optimizations in the energy consumption. The objective of this work was to study the optimization of the numeric representation of a silo-dryer system, comparing the results of three different models available in the software FLUENT® 19.2: Eulerian Multi phase Model for Granular flow with packed bed configuration disabled, the same model but with the packed bed configuration enabled, and the porous zone single-phase modelling. The convergence efficiency of these models was also analyzed through the results of the numeric residue, and the influence of the relaxation factor in the simulation results. The behavior of solid volumetric fraction, air velocity and bed temperature were qualitatively examined with hot air at the inlet. It was found that the momentum relaxation factor influenced the results. Moderately lower factors allowed for faster convergence without significant particle behavior change. Monitoring the mass residue, the enabled packed bed modelling presented lower residuals, while the porous zone modelling presented higher residuals. The packed bed and porous zone modelling reported lower air velocities in comparison to the disabled packed bed modelling, and presented satisfactory heat transfer through the temperature profiles.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 The influence of natrural fermentation on coffee drink quality(Editora UFLA, 2020) Pereira, Leandro Ferreira Bernardes; Franco Junior, Kleso Silva; Barbosa, Camila Karen ReisCoffee quality refers to various methods used in farming, selective harvesting that assist in quality preservation and drying methods to be performed. Some drying methods that are being performed fermentation procedures have helped in obtaining specialty coffees. The objective of the research was to evaluate the effects of controlled natural fermentation of coffee through the temperature and time and its influence on the quality of coffee, according to the prescribed attributes in SCAA methodology, the type of coffee drink and time for drying grain. The research was carried out at Lavrinha farm, located at Poço Fundo (south of Minas Gerais), with coffee fruits of Catuaí Vermelho IAC 144 cultivar and selective and manual harvesting. The treatments with temperature-controlled fermentation of 30 and 40 °C (1, 2, 3, 6 and 12 hours) and the control treatment were used with three replications in a randomized block system (DBC) in a factorial scheme. After fermentation, the batches were dried to 11.5% humidity and evaluated according to the SCAA (2015) methodology. The natural fermentation induced by temperature (°C) and time (hours) directly influenced the drink quality, resulting in a coffee with a score of 82 to 84 points, with attribute aggregation and special classification. Natural fermentation with temperature up to 40 °C and time control of 3 ,1 and 24 hours resulted in an improvement in coffee quality by 84 points.