Conferences 2024

Eduardo Duque-Dussán

Students Conference: Faculty of Tropical AgriSciences, Czech University of Life Sciences October 2023, Prague, Czech Republic.

Abstract

Due to the extended drying time open-sun and solar drying of coffee procedures undergo, the development of microorganisms, mycotoxins and molds threaten the product. Alternatives such as mechanical dryers are available, nevertheless, their running costs and setups are usually expensive and unaffordable for small-scale coffee growers. Therefore, this research aimed to design, build and evaluate a hybrid solar dryer which mixes solar and mechanical drying principles. It uses a traditional solar tunnel-type dryer as a base featuring a biomass burner which uses coffee trunks left from the yearly crop renovation as biofuel. A heat exchanger heats the drying air, afterwards blown into a plenum chamber that homogenizes the air's static pressure before crossing the coffee bed, ensuring an even moisture removal. Also, the hybrid unit includes a photovoltaic system to obtain a fully self-sufficient drying unit. The newly developed dryer was tested under three different configurations: Solar and mechanical day and night (C1), solar during the day and mechanical during the night (C2) and fully solar with non-mechanical aid (C3). The results displayed a notable drying time reduction in the three evaluated configurations: C1 reduced the drying time by 70.47%, C2 by 45.75% and C3 by 21.5%. Also, the predictive model for different plenum chamber heights was obtained through computational fluid dynamics simulations, where the ideal height was 0.25 m. A biomass consumption of 1.9 kg h−1 was registered. Also improved temperature and relative humidity profiles were achieved. Its design easily adapts to the existing tunnel and parabolic-type solar dryers. 

Keywords: Biomass; Coffee; Coffee drying; Hybrid dryer; Tunnel dryer; Mechanical drying.

Eduardo Duque-Dussán, Jan Banout

4th International Multidisciplinary Conference for Young Researchers (MCYR) October 2023, Prague, Czech Republic.

Abstract

Background: Selective harvesting of coffee has always been a challenge to those coffee growers who live in mountainous regions; the access of harvesting cars and tools to the plots is expensive and complicated. The labour is also scarce and intensive. Therefore, designing an apparatus that helps harvest the ripe fruits without damaging the tree is necessary. Methods: Following the theory of natural frequency and modal analysis, the critical vibration frequencies of coffee at different ripening stages were calculated; afterwards, an air-pressurized nozzle was designed to deliver air shots at the desired frequency collapsing the peduncle of the fruits, harvesting those od interest while reducing all type of mechanical damage. Results: Although all the experiments were performed in the laboratory, the fruit was successfully removed, and its vibration profiles were also characterized. Conclusions: The obtained information allows to design of different vibration-based devices that could ease the selective harvesting of coffee.

Keywords: Coffee; Frequency; Modal Analysis; Selective Harvesting; Vibration.

Paula A. Figueroa-Varela, Eduardo Duque-Dussán

4th International Multidisciplinary Conference for Young Researchers (MCYR) October 2023, Prague, Czech Republic.

Abstract

Background: When wet-processed coffee reaches its equilibrium moisture content (10-12% (wb)), remoisturizing of the seed can happen, mainly when using natural convection drying methods. Considering that in Colombia, around 96% of the coffee growers are smallholders and their use of solar drying technologies is high due to their easy and cheap operation, it is compulsory to develop techniques to avoid coffee remoisturizing applicable to solar drying apparatuses. Methods: Dry coffee (10% (wb)) was laid on solar drying in different configurations: Piled, covered with a geomembrane, packed in fibre bags, and flattened. Overnight, the moisture regain was evaluated. Results: Although all the configurations displayed moisture regain, the piled-covered coffee gained less from all the evaluated methods. Conclusions: The piled-covered method is an easy in-farm applicable method; therefore, the coffee growers can easily apply it and reduce the risk of developing microorganisms, fungi and mycotoxins due to moisture regain in their product.

Keywords: Coffee Drying; Equilibrium Moisture Content; Moisture Content; Remoisturizing; Solar Drying.

Eduardo Duque-Dussán, Jan Banout, Juan R. Sanz-Uribe

Tropentag Conference September 2023, Berlin, Germany.

Abstract

Open-sun and solar drying of coffee are used worldwide to lower the moisture content of the beans. Their easy setups and low running costs attract coffee growers; however, these processes are difficult to control and predict due to their dependence on climate conditions. Due to the extended drying time these procedures undergo, the development of microorganisms, mycotoxins and moulds threaten the product. Alternatives such as mechanical dryers are available, allowing to dry large amounts of coffee in shorter times; nevertheless, their running costs and setup are usually expensive and unaffordable for small-scale coffee growers. Therefore, this research aimed to design, build and evaluate a hybrid solar tunnel dryer which mixes solar and mechanical drying principles. It uses a traditional solar tunnel-type dryer as a base featuring a biomass burner which uses coffee trunks left from the yearly crop renovation as biofuel. A heat exchanger heats the drying air, afterwards blown into a plenum chamber that homogenizes the air's static pressure before crossing the coffee bed, ensuring an even moisture removal. Also, the hybrid unit includes a photovoltaic system to obtain a fully self-sufficient drying unit. The newly developed dryer was tested under three different configurations: Solar and mechanical day and night (C1), solar during the day and mechanical during the night (C2) and fully solar with non-mechanical aid (C3). The results displayed a notable drying time reduction in the three evaluated configurations, low biomass consumption and improved temperature and relative humidity profiles. Its design easily adapts to the existing tunnel and parabolic-type solar dryers.

Keywords: Biomass; coffee; coffee drying; hybrid dryer; tunnel dryer.

Eduardo Duque-Dussán

Scientific Seminars, National Coffee Research Center of Colombia (Cenicafé). April 2023, Manizales, Colombia.

Abstract

La calidad final del café se ve afectada por el proceso de secado, el cual depende de las propiedades termofísicas del grano de café y del aire de secado. Cenicafé ha desarrollado las variedades de café Cenicafé 1 y Castillo® altamente productivas y resistentes a enfermedades, pero aún no se han investigado sus propiedades termofísicas específicas.

Este estudio se enfocó en determinar las propiedades termofísicas del café pergamino de estas variedades en cinco diferentes niveles de humedad (53%, 42%, 32%, 22% y 11%), utilizando técnicas y métodos optimizados para garantizar alta precisión y exactitud.

Se encontró que estas variedades tienen granos más grandes, pesados y densos, además su conductividad térmica y calor específico a granel son más altos que en otras variedades. A medida que se eliminó la humedad, la densidad aparente, la densidad del grano, la masa, el calor específico del volumen y la conductividad térmica total disminuyeron.

Conocer estas propiedades permitirá a los productores y las instalaciones de procesamiento de café mejorar los procesos de secado y tostado para producir un mejor producto final. También pueden actualizarse los modelos matemáticos desarrollados para estimar los tiempos de secado del café y mejorar la precisión de las predicciones.

Zuzana Rázkova,  Adéla Čermáková, Eduardo Duque-Dussán

ELLS Conference. September 2022. Prague, Czech Republic.

Abstract

When coffee is processed with the wet method, the seed shrinks during the drying phase as thegrain loses water. As a result, when shrinking takes place an air chamber is generated betweenthe parchment layer of the coffee and the seed; seeing that the air is not a particularly efficientheat conductor, this generated volume will act as a resistance to the heat being supplied by thedrying air. Moreover, the heat conductivity of the system seed-air-parchment will be reduced,resulting in a low capacity drying process that may lead to further mycotoxin andmicroorganism development. An image analysis of 100 cross-section pictures in five differentplanes of parchment coffee (Coffea arabica L.) was performed to determine the largest distance(A) between the parchment and the seed. Then, a heat transfer analysis employing finiteelement methods (FEM) was conducted to model the heat loss through the considered layersin the most critical point (A) and then it was extrapolated to a 3D analysis also using FEM toobtain a more accurate study employing real 3D scanned coffee beans. While the linear studyshowed a loss of approximately 6°C, the 3D study calculated that 7.5°C would be retained bythe air chamber.

Keywords: Drying; Image Analysis; Moisture; Parchment Coffee.

Eduardo Duque-Dussán, Jan Staš, Jan Banout.

Tropentag Conference September 2022. Prague, Czech Republic.

Abstract

One of the most important physical properties of the coffee grain to consider when drying is the surface area, seeing that the moisture diffusion is a function of the size of the grain. Also, the coffee bed represents a porous volume throughout which the drying air circulates, such porosity is also given by the seed’s dimensions and void spaces within the grain layer. When the coffee bean is dried, a volumetric shrinkage occurs, and even though its change can be easily measured in terms of length, width and depth, the surface area variations must be approximated since the bean’s shape is irregular. Contemplating this, three wet coffee grains (Coffea arabica) were 3D scanned and digitised, upon which a transient mass diffusion finite element method (FEM) simulation was performed from an initial moisture content of 55 % (w.b) until reaching the required moisture content of 10 % (w.b). The superficial area of the three grains was evaluated at different moisture content stages during the drying simulation process, so the ongoing shrinkage could be recorded. Afterwards, real coffee grains at 55 % (w.b) were laboratory-dried, keeping the same parameters as the simulation (air temperature, relative humidity, airflow, and direction); samples were removed at different moisture content levels and their parchment was withdrawn and spread on a cover glass; their image was taken and subsequently processed to obtain the actual surface area. Both the FEM simulation and the image processing results were compared, finding a level of similarity of 96.5 %, where an average 7.3 % volumetric shrinkage was observed. At the same time, the drying time was compared, displaying that both results shared an accurate and high similarity. 

Keywords: Coffea arabica; coffee drying; image processing; mass diffusion; seed shrinkage.

Carlos I. Cardona, Héctor A. Tinoco, Luis Perdomo-Hurtado, Eduardo Duque-Dussán, Jan Banout

International Conference on Electrical, Computer and Energy. July 2022, Prague, Czech Republic.

Abstract

This study deals with the design of a pneumatic air-jet nozzle for coffee fruits harvesting purposes. In steady-state conditions, a CFD finite element model was implemented to validate the nozzle design. We studied variations in the cavity length and outlet diameter of the nozzle under 5 bar of pressure and 140 Lt/min of caudal flow. Using additive manufacturing, three prototypes of the nozzles were created in onyx material. In addition, a pneumatic assembly was built by integrating a nozzle with a solenoid electro valve that allowed air to be discharged from a compressor. Using a high-speed video camera, we conducted an experiment to understand the air jet morphometry of each nozzle. The electro valve was operated at 42 Hz and the operating conditions were chosen based on simulations. CFD-derived velocity was compared with the filmed jets from the experiments to illustrate its turbulence. The results were analyzed in terms of their capacity to produce punctual impacts on coffee fruits Coffea Arabica L. var Castillo. The results of this study suggest that future studies could be conducted to investigate the impact capacity of pneumatic air-jet nozzles on coffee fruit excitation in terms of vibrational measurements.

Keywords: Nozzle, CFD, air jet, pneumatic, solenoid electro- valve, morphometry, high speed camera

Eduardo Duque Dussán, Zuzana Rázková,  Jan Banout.

International Scientific and Advanced Conference: “PROSPECTS OF BIOENERGY CROPS FEEDSTOCK PRODUCTION ON RECLAIMED MINE LANDS” June 2022, Dnipro, Ukraine.

Abstract

  When coffee is wet-processed, it produces large amounts of wastewater containing high levels of BOD, COD, total and suspended solids, NTk, phosphorus, and other pollutants. There are several processes developed by the National Coffee Research Center (Cenicafé) to treat the effluent produced. Acidogenic/hydrolytic reactors, followed by methanogenic reactors, are among the most efficient ones. It has been demonstrated that the process can correct the outlet stream by 78.67%, but only if all variables are controlled. Consequently, a triple-pass vetiver grass wetland was proposed in this study to be located after the methanogenic reactor, allowing even higher remediation levels without considering the characteristics of the incoming stream. A sequential modular approach was used to simulate the process, and the final discharge flow showed a remediation efficiency of 97.75%. The methanogenic reactor can produce biogas that can be cleaned and used for a range of applications, including drying coffee and household purposes.

Eduardo Duque-Dussán, Jan Banout.

CASEE Conference “Sustainable agriculture in the context of climate change and digitalization” June 2022, Prague, Czech Republic.

Abstract

Cacao producers usually face a complex situation when drying their product using open sun drying processes, considering that this dryingmethod is highly affected by the weather conditions. Achieving a final bean moisture content between 6 and 8% (w.b) will lower the possibilitiesof bacteria, fungi and other microorganisms growth along with a high storage and bean quality. However, because of the approximate initialbean moisture of 70% (w.b), and due to the method's dependence on the variating tropical climate, it can take up to ten days in the best case,threatening the product's integrity. This is why different solar drying units and technologies have been developed, seeking to reduce the bean'sdrying time and quality preservation; one of the most important technologies is the so-called hybrid solar dryer, which uses a collector to heatthe ambient air which is afterwards travelling across the dryer's domain. The connection between the collector and the drying chamber is usuallylaterally arranged at the collector's inclination; however, a new system was designed with an air inlet at the bottom of the unit, vertically arranged to compare the drying air behaviour and velocity and distribution both dryers. After performing a Computational Fluid Dynamics (CFD)simulation, it was seen that the new proposal allows the air to distribute homogeneously and keep a high velocity, facts that will impact thedrying process positively. Based on these results, the process was also simulated numerically, obtaining both units theoretical drying time, wherethe new proposal displayed a significant time decrease. The drying performance was improved, being translated as a potential upgrade of theprocess, directly impacting its efficiency and production outputs.

Keywords: Cacao beans; Drying; Moisture removal

Jan Staš, Eduardo Duque-Dussán, Andrés Villada, Jan Banout.

2nd MULTIDISCIPLINARY CONFERENCE "Sustainable Development Trends and Challenges under COVID-19" November 2021, Sumy, Ukraine.

Abstract

Background: Meat is one of the most valuable livestock products. It serves as the primary source of protein for many people, especially in developing countries, where the demand for meat is still rising. Poor equipment and knowledge about meat preservation highlight the importance of feasible 

alternatives for rural populations. Drying or dehydration is one of the oldest and still most popular methods for meat preservation. Drying the product directly in the sun, which is still used in rural areas of Vietnam, is associated with many difficulties, such as the possibility of contamination by 

microorganisms, pests, or molds. Moreover, it changes the organoleptic properties of the product. Therefore, this study focuses on the sensory analysis of beef and buffalo jerky dried in different conditions, concretely in the laboratory oven (LD) and active solar dryer (ASD). Methods: Beef and buffalo raw meat samples were prepared, and two different types of pre-treatments were applied: marinating the samples in traditional Vietnamese marinade and frying the samples in oil before drying. Prior to drying, the physicochemical characteristics of the raw meat were determined, such as dry matter content (%), Warner-Bratzler shear force (N), and color. The aim was to find a correlation between the dryers and the sensory properties of the meat and the relationship between the different 

types of pre-treatments applied. The sensory panel also aimed to investigate if different pre-treatments (curing and frying) and different kinds of meat (beef and buffalo) can influence the results of sensory profile analysis. Moreover, these samples were also compared with dried beef meat obtained from the local market. Results: Organoleptic properties of five samples were assessed by a trained 13-member degustation panel. The best-scored sample was beef meat from the local market, followed by beef meat dried in ASD and buffalo meat dried in ASD. Frying the samples before drying did not affect final organoleptic properties significantly.

Keywords: Solar drying; meat drying; meat jerky; renewable energy; organoleptic properties; sensory 

analysis.

Eduardo Duque-Dussán, Andrés Villada, Jan Staš, Jan Banout.

2nd MULTIDISCIPLINARY CONFERENCE "Sustainable Development Trends and Challenges under COVID-19" November 2021, Sumy, Ukraine.

Abstract

Background: When processing coffee through the wet method, it is required to reduce the grain’s moisture content to levels that inhibit the growth of microorganisms, mycotoxins, bacteria, or molds, allowing the production of a high-quality product meeting the proper commercialization and storage standards. Therefore, the different drying technologies face a complex task considering that they must ensure an acceptable final seed moisture content. Achieving this is especially difficult for those drying processes that use natural convection or open solar drying as the main source of energy to remove the water within the seed, seeing that these processes depend on climate factors that can change rapidly over time. These methods can be considered as stochastic, meaning that their predictive behaviour is challenging to attain. On the other hand, the machine drying of coffee is a deterministic process that is predictable if the initial conditions are known. However, no record in the literature illustrates the drying phenomenon of a single seed under these two different methods so as to determine the moisture distribution within the grain’s inner domain. This research aimed to perform a Finite Element Analysis (FEA) study, simulating the drying process of a single coffee bean. Being defined as a transient mass diffusion model under the machine and natural convection conditions so the drying behaviour of both case scenarios can be predicted and controlled depending on the process conditions. Methods: A wet grain ±53% (w.b) was 3D scanned and digitized as the FEA simulation geometry. The diffusion of the water between the grain and the atmosphere was further defined by a diffusion coefficient, subject to the temperature and humidity. Three cases were studied: drying of the grain under machine drying at 3 different temperatures (50, 45 and 40°C) with their corresponding relative humidity and air velocity, natural convection drying at environment conditions (wet and dry season), and natural convection (wet and dry season) including the day and night temperature and relative humidity variation. Results: The results agreed with the experimental data found in the literature defining the coffee as a grain bed in both machine and sun drying. However, the graphical distribution of the moisture, predictive drying curves, diffusion coefficients and isotherms were obtained for all phenomena. Conclusions: A predictive Finite Element Model (FEM) was designed to obtain relevant data of the drying performance of both machine and natural convection drying under certain conditions.

Keywords: Coffee Drying; Finite Element Model; Seed; Moisture Diffusion.

Zuzana Rázková, Eduardo Duque-Dussán, Jan Staš, Jan Banout.

Green (r)evolution: from molecules to ecosystems. ELLS Conference. November 2021, Warsaw, Poland.

Abstract

Meat might be the most valuable livestock product, it serves as the primary source of protein in human diet. Rising meat demand in developing countries along with inadequate equipment and process knowledge highlight the importance of feasible alternatives for rural populations for meat preservation.

Open-sun drying is one of the oldest and still very popular method for food preservation in many rural areas in Vietnam. However, it is often associated with several drawbacks for example contamination by microorganisms, pests, fungi, or moulds which are a constant threat to the product itself because of its perishable nature, but also for the human health. Hence, this research focuses on implementing a solar drying unit to process traditional Vietnamese beef and buffalo jerky as an alternative to open-sun drying and laboratory-type dryers (electric ovens).

Beef and buffalo meat samples were prepared under two different pre-treatments, marinated in the Vietnamese traditional marinade and pan-fried in oil before drying. The drying was conducted in the Active Solar Dryer (ASD) and in the Laboratory Dryer (LD). The main goal was to find a correlation between dryer type and drying speed, and to verify if a relationship with the applied pre-treatment exists. It was noted, that both drying efficiencies (ASD and LD) were similar, it was also found that depending on the pre-treatment applied, the marinating influence the process, slowing the drying activity in both drying units, nevertheless it was not statistically significant. The same effect occured when frying the samples before drying, however, the drying time increment in the LD was statistically significant (p<0.05). There was no significant difference in the organoleptic and physical properties of the beef and buffalo meat.

Keywords: Beef jerky; Solar drying; Meat drying; Renewable energy; Organoleptic properties 

Zuzana Rázková, Yamen Homaidan Shmeit, Eduardo Duque-Dussán, Eloy

Fernández-Cusimamani

IX COLAPLAMED Latin American Congress of Medicinal Plants. October 2021, Quito, Ecuador.

Abstract

The Lamiaceae family contains more than 6000 species and most of them hold healing properties by a high content of essential oils used against

nausea, anxiety, cancer, and other health issues. To increase the quality and quantity of plant secondary metabolites, many breeding techniques were developed, and one of them is polyploidization. The aim of this study was to perform a review of polyploidy induction in vitro and in vivo on medicinal species from the Lamiaceae family. Data was collected from scientific databases: Web of Science, Scopus and Science Direct, between

1996-2021. 

The obtained data was evaluated quantitatively and qualitatively according to:

• Part of the plant used.

• Antimitotic agent (type, exposure time and concentration).

• Polyploidization method used.

The common biochemical changes were also described, defining their benefits on the pharmaceutical use of the plant.

Eduardo Duque-Dussán, Jan Banout 

Tropentag Conference. September 2021, Hohenheim, Germany. 

Abstract

Considering that the coffee harvest peaks in Colombia coincide with the rainy seasons, the coffee growers face many complications when attempting to sun dry their coffee due to the high cloudiness and low direct sun radiation; deriving in post-harvest processes delays or incomplete grain dryness, risking the quality, innocuousness and safety of the product. That is why local workshops started to fabricate low capacity mechanical dryers simulating the industrial coffee drying equipment’s working principles. One of the most commercialised units is a triple tray rectangular-shaped convective dryer with a net drying capacity of 31.25 kg of dry parchment coffee per 21-hour batch, providing an acceptable solution to the drying concerns. However, the process seemed improvable, focusing mainly on the dryer’s geometry, air inlet and coffee bed thickness, seeking to enhance the airflow inside the unit, and reducing the product’s drying time. Hence, a new dryer design was proposed displaying a circular shape, a lower grain bed thickness and a vertical air inlet accompanied by a diffusive tray. Based on the Thompson and Michigan State University mathematical models for grain drying, both units were simulated to obtain their theoretical drying time. A computational fluid dynamics simulation was also conducted to observe the drying air’s behaviour inside the units; the circular drying unit presented a notable theoretical reduction in the drying time. It also displayed a more homogeneous and uniform air distribution, optimising the dryer’s performance, deriving into improving the grower’s profitability, dynamising the post-harvest processes to avoid product spoilage and reducing the electrical and gas consumption.

Keywords: CFD Simulation; Coffee drying; Parchment coffee; Porous bed.