Coffee Science (E-Journal)
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Modeling effectiveness analysis of momentum and heat transfer in a fixed bed silo-dryer through computational fluid-dynamics
Get PDFThe drying procedure is capable of increasing the shelf life of many products, and facilitates its transport and storage. However, in the subsequent stages of the drying, the operation can display inefficiencies. An alternative to mitigate this is the use of a silo-dryer, an equipment that allows the simultaneous drying and storage of the material. Coffee is a product of great importance in the industry, and its market value is linked to the physical and sensorial qualities of the seed. The silo-drier can ensure these qualities through intermittent drying and optimizations in the energy consumption. In this work the operation of a cylindrical silo-dryer through computational fluid-dynamics was analyzed, studying the convergence for different numerical models. The behavior of volumetric fraction, air velocity and seed temperature were qualitatively examined with hot air at the inlet. The simulations were carried out through the software FLUENT® 19.2 using three different numerical models: the Eulerian Multiphase 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. 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.
Key words: Cfd; Coffee; Drying; Eulerian; Multiphase
Physicochemical, microbiological, and sensory characterization of fermented coffee pulp beverages
Get PDFCoffee pulp is the first by-product generated from coffee processing, a contaminating residue due to its composition and production volume. So, this research presents the use of coffee pulp with honey and sugar cane juice to elaborate alcoholic beverage and infusion. The harvested coffee was washed, pulped; the pulp was distributed in 3 treatments, by duplicates, (T) coffee pulp and water, (M) coffee pulp, water and honey, (G) coffee pulp and sugar cane juice. Then, each treatment was brought to 85 °C for 15 minutes, warmed up and yeast was added to each container. Fermentation was carried out for 14 days at 15 °C. After the liquid was separated from the pulp, the liquid fraction was left to ferment another 14 days, it was clarified with bentonite, it was bottled and for 102 days mature, the degrees of alcohol was measured by simple distillation. The pulp was placed in an oven at 75 °C for 3 days, the chemical composition was analyzed by FTIR, it was packed in hermetic bags, the dry coffee pulp was used to prepare an infusion. For its use, a fermented drink and an infusion were elaborated, evaluating physicochemical, microbiological, and sensorial characteristics through three treatments. The fermented drinks presented values of alcohol degrees 7°- 6°. The treatment with honey obtained a greater acceptance followed by the treatment with sugar cane juice. The infusions were acceptable, differentiated by herbal notes, pleasant aromas, and sweet flavors. In the pulp, the following were characterized by FTIR chemical compounds and wavelengths that show their absorbencies; caffeine with ranges of 2920-2850 and 1620 cm-1, 3280 cm-1 H2O, 1740 cm-1 lipids, 1240 cm-1 chlorogenic acid, and 1015 cm-1 carbohydrates. Finally, the infusions with coffee pulp were accepted by the evaluators, especially those that went through the fermentation process with honey and sugar cane.
Keywords: Caffeine; Coffee; Chemical compounds; Fermentation; Sensory analysis
Physiological aspects and yield in coffee progenies with large beans
Get PDFGenetic coffee breeding is aimed at increasing yield associated with tolerance or resistance to biotic and abiotic factors, besides providing a better beverage quality and supplying the demand for bigger beans. The efficiency in photosynthetic activity can limit produce and diversify genotypes, mainly under adverse environmental conditions. Consequently, the importance of selection of Coffea arabica L. regarding these characteristics stands out. Therefore, the objective of this paper was to measure the physiological characterization and yield of Coffea arabica L. progenies with large beans “Big Coffee VL”. Twelve productive progenies were selected and classified according to fruit size (“small”, “medium” and “large”), which were: S14, S23, S34, S36, M4, M5, M14, M20, L10, L12, L17 and L31. Net photosynthetic rate (A), stomatal conductance (gs), transpiration rate (E), water use efficiency (WUE), internal carbon (Ci), intercellular CO2 concentration in the mesophyll were evaluated on the current external CO2 concentration (Ci/Ca), besides vapor pressure deficit (VPD), leaf temperature (Tleaf), indirect determination of the relative levels of chlorophylls a, b and total, in addition to bean yield in two crops. The Tocher grouping resulted in the formation of 4 groups, and progenies M4, L10 and S34 remained in isolated groups. Progeny L10 stood out for higher mean values of A, gs and Ci; the opposite behavior was observed in progeny S34. Progeny M4 is noteworthy as the one with the highest yield in the two years considered, in addition to presenting high photosynthetic rate and chlorophyll indexes. It is concluded that the progenies of “Big Coffee VL” show variability for physiological parameters and productivity. Progenies S14, M4 and L10 stood out, and S14 was more efficient in the use of water; M4 was the most productive and L10 stood out in terms of gas exchange.
Key words: Chlorophyll; Coffea arabica L.; Gas exchange; Genetic breeding
Resistance and effect of insecticide-treated coffee berries of different varieties to the penetration of Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae)
Get PDFABSTRATO
The control of Hypothenemus hampei, coffee berry borer (CBB) is difficult as the insects infest inside coffee berries and are thus protected from agrochemicals. Coffee varieties with an increased penetration time by H. hampei can help control this pest tends to be exposed insecticide action for long time. Therefore, this study aimed to determine the time taken by H. hampei to entirely penetrate berries of different coffee varieties and whether insecticides have any influence on the penetration time. Thus, twenty five berries of 27 coffee varieties in the green phenological stage were introduced in rubber caps, with the berry crown exposed.. From this experiment, seven varieties were selected for another bioassay, with insecticides being sprayed on the berries. Copulated female H. hampei were released on the berry, and the penetration time was assessed. Finally, a free-choice test to verify H. hampeifood preference was performed, using the same seven coffee varieties. The insects took longer to penetrate the Arara, Catuaí Vermelho IAC 144, and Guará coffee-variety berries. Moreover, all coffee varieties treated with the insecticide cyantraniliprole inhibited penetration by H. hampei. Most coffee varieties treated with insecticides showed a prolonged penetration time by H. hampei compared to the same untreated ones, except for the chlorpyrifos insecticide in the Catuaí IAC 144 and IAC 62 varieties. Additionally, H. hampei showed no feeding preference among the different tested coffee varieties.
Key words: Coffea arabica; Chemical control; Food preference
Physicochemical parameters of arabica fermented coffee in different altitudes
Get PDFThe coffee quality interacts with different processes, techniques, analyses, and concepts. This study applied six different forms of wet fermentation to coffee from different altitude ranges to understand how coffee quality interacts with the physicochemical profile and its possible relations with sensory variables. Statistical analysis was performed through combined analyses of variance of the experiments, and the means were compared by the Tukey test considering the significance level of 5%. Regression models were tested by the F-test and the parameters by the t-test, followed by Pearson correlation analysis between the sensory and physicochemical characteristics and between physicochemical variables. The results indicate a correlation between sensory and physicochemical variables for total titratable acidity and indicate that these compounds are affected by the manner of fermentation appliedas well as the edaphic and climatic conditions.
Key words: Coffea arabica; Chemical interaction; Fermentation; Processing
Tasters’ performance in a coffee quality contest in Brazil
Get PDFThe objective of this work was to evaluate the performance of coffee tasters in five annual editions of Minas Gerais Coffee Quality Contest. The repeatability coefficients of the tasters’ scores for sensory attributes were estimated, as well as the minimum numbers of tasters required for consistent sensory results, and the groups of tasters by (dis)similarity of sensory scores. For the repeatability analysis, the treatments (coffees) were tested with the repetitions, constituted by the tasters. The repeatability coefficients were estimated using the analysis of variance, principal component and structural analysis methods. The minimum number of tasters was obtained based on pre-established determination coefficients. Euclidean distance matrices between tasters were determined, which were used as a measure of dissimilarity for cluster analysis by the Tocher optimization method. The tasters’ performancein five annual editions of Minas Gerais Coffee Quality Contest is reliable using COE or SCA sensory analysis protocols. Although not fully calibrated, most tasters are grouped with similar cupping results. Unless efficient calibration prior to the contest is adopted, the number of tasters to be used in the next contest editions can not be drastically and randomly reduced, since the estimated minimum number varied over the years. Calibration activities are suggested to improve two main aspects of the Minas Gerais Coffee Quality Contest: distinguishing the best coffees and trainning tasters.
Key words: Specialty coffee; Sensory analysis; Coffee beverage; Repeatability analysis
Comparision of different application methods to biological control Hypothenemus hampei
Get PDFThere are several studies that deal with the problem of infestation by Hypothenemus hampei in Coffeea arabica. However, the ways of applying products based on entomopathogenic fungi are the same as those used for chemicals. The objective of the research was to comparison different methods of application of Beauveria bassiana against H. hampei. The experiments were developed in laboratory, with blastospores and B. bassiana airborne conidia powders were carried out. Application methods based on immersion, Potter Spray Tower and walking on treated surface. Were three experiments were carried out for each method. Bioassays’design comprised seven treatments (including the control), with five repetitions (each) and 25 beetles per repetition. Suspensions were standardized at 2.4×109, 1×109, 5×108, 1×108, 5×107 and 1×107conidia.mL-1. Conidia powder presented initial concentration of 1.14×1010and it was standardized at 1.14×109; 5.7×109; 1.14×108; 5.7×107; 1.14×107 and 5.7×106 conidia.g-1. A simultaneous test was also carried outbased to the three application methods; treatment comprised conidia powder concentration of 1x108 and the control. Data were subjected to analysis of variance, which was followed by Tukey test (P<0.05) and, CL50, in the SPSS 12.1 software. The mortality better rates of H. hampei exposed to B. bassiana IBCB66 were1×108(immersion), 1×109 (Potter Spray Tower) and 1×108(walking), where as mean LC50were 6.1×108, 4.1×108, 2.4×108conidia.mL-1for each method, respectively. The highest mortality rate was recorded in the walking tests on the conidian powder at a concentration of 1×108 conidia.g-1 for the three repetitions of the method and also in the simultaneous test.
Key words: Blastospores; Conidian powder; Mortality; Suspensions
First report of Aethalion reticulatum (Linnaeus, 1767) (Hemiptera: Aethalionidae) infesting plants of Coffea arabica (Linnaeus, 1753) (Rubiaceae)
Get PDFCoffee is of great socio-economic importance, and in this scenario Brazil stands out as the largest producer and exporter of coffee beans. However, the coffee tree is susceptible to the attack of several insect pestshe main ones being the berry borer and leaf miner. However, other insects may be present in the crop, and their identification is important for the elaboration of mitigation measures. To date, the presence of the leafhopper Aethalion reticulatum (Linnaeus, 1767) (Hemiptera: Aethalionidae) in Coffea arabica (Linnaeus, 1753) (Rubiaceae) plants has not been reported in the literature. Thus, the present study aimed to describe the occurrence of A. reticulatum in arabica coffee plants on the Campus of the Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais, Brazil.
Key words: Fruit leafhopper; Insect pest; Coffee crop; Infestation
Sensory Assessment of Gayo arabica coffee taste based on various varieties and manual brewing devices
Get PDFArabica coffee (Coffea Arabica) becomes one of the most in-demand types by the community due to its typical taste. The right method and coffee brewing device are needed to obtain this typical taste of coffee. One of the coffee brewing methods that keeps developing until now is the manual brewing method. This study aims to find the sensory characteristic of Gayo Arabica coffee taste in various varieties with manual brewing devices by using Analytical Hierarchy Process (AHP) method. Manual brewing devices used were Vietnam Drip, French Press, V60, Eva Solo, and Filter, while the chosen varieties are Tim-tim (Gayo 1), Bor-bor (Gayo 2), and P88. The study result showed that based on the preference of product acceptance by the panelists, the most chosen criteria of taste sensory were flavor (0.253), followed by aftertaste (0.222), sweetness (0204), acidity (0.165), and body (0.155). The variety chosen as the best variety with manual brewing was Tim-tim in various manual brewing devices, which are V60 (0.156), French Press (0146), and Eva Solo (0.140). The next alternatives brewing devices were Vietnam Drip (0.127) and Filter (0.109). Thus, it can be concluded that flavor is the top priority that influences Gayo Arabica coffee's taste. Tim-tim with manual brewing devices (V60, French Press, and Eva Solo) is preferred over other varieties in this study. This finding also becomes a recommendation that the variety for the best serving of Gayo Arabica coffee brew with the most preferred taste with manual brewing devices is Tim-tim.
Key words: Arabica coffee; Manual brewing; AHP method; Pairwise comparison
Functional diversity of microbial communities associated with fermentation processes in coffee (Coffea arabica L.)
Get PDFMucilage fermentation conducted to degrade and remove coffee mucilage, is an important stage to also define coffee quality, but each microorganism’s contribution to the final quality is not yet known. Therefore, tools are needed to easily identify this relationship in order to be used to enhance coffee quality. The present manuscript describes the behavior of the microbial communities present in fermentations conducted under various conditions, which produced differences in the sensory quality of the coffee as assessed by the community-level catabolic profile approach. The coffee samples camefrom six different fermentation processes that produced coffee in two quality classifications according to the Specialty Coffee Association (SCA) protocol: very good and excellent. Functional diversity of the microbial communities and substrate consumption were compared through analysis of variance. The multidimensional scaling analysis was used to identify the similarities or differences between treatments. The indices of functional diversity revealed significantdifferences and direct proportionality with the quality rating. Diversity index (H) was between 2.09 and 2.71 and Evenness was between 1.75 and 2.21. The consumption of groups of substrates was different between fermentations, especially in carbohydrates and carboxylic acids, and the greatest consumption of these was found in the excellent-quality coffee. The different fermentative processes evaluated by this technique showed a high metabolic activity related to the great diversity of substrates given to the microbial communities and microorganisms involved, causing reactions that had influence on the final quality of the product.
Key words: Catabolic profiles; Coffee quality; Diversity indices