Mathematical Modelling and Immediate and Latent Quality of Natural Immature Coffee Under Different Drying Conditions

Andrade, Ednilton Tavares de; Lemos, Isabella Avila; Dias, Camila de Almeida; Rios, Paula de Almeida; Borém, Flávio Meira

doi:10.1590/1809-4430-eng.agric.v39n5p630-638/2019

Cited by 5 publications

(2 citation statements)

References 18 publications

(18 reference statements)

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“…To determine the moisture content atthe hygroscopic equilibrium of immature coffee, Equation 3 was used (Andrade, 2019):…”

Section: Methodsmentioning

confidence: 99%

Origin of black-green defect in the artificial drying of immature coffees

Rios

Cardoso

Andrade

2021

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The 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 m 2 .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.

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“…To determine the moisture content atthe hygroscopic equilibrium of immature coffee, Equation 3 was used (Andrade, 2019):…”

Section: Methodsmentioning

confidence: 99%

Origin of black-green defect in the artificial drying of immature coffees

Rios

Cardoso

Andrade

2021

Self Cite

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“…Dentre os graus de maturação dos frutos do cafeeiro, os imaturos são os mais susceptíveis à danos térmicos devido a temperatura do ar de secagem (Andrade et al, 2019).…”

Section: Introductionunclassified

Secador de camada fixa: uma adaptação para melhorar a secagem de café natural no Brasil

Oliveira

Andrade

Moreira

et al. 2020

RSD

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The drying of coffee by means of fixed layer dryers has been widely used by Brazilian coffee growers. However, high gradients of water content formed in these dryers are frequently reported, as well as the presence of microorganisms. The present work was developed with the purpose of monitoring the performance of these dryers and their effect on the final quality of the product, comparing to an adaptation made in conventional fixed layer dryers. During drying, the following characteristics were monitored at various points in the drying chamber: temperature of drying air, intergranular air, exhaust air, and ambient air; relative humidity of the drying air, the ambient air, and the exhaust air and the water content of the product at different points and heights in the drying chamber (0.12; 0.36 and 0.60 m). Among the dry product evaluations, color analysis and microbiological analysis were performed. According to the results obtained, drying with inversion of the airflow resulted in a water content gradient of 0.4% (b.u.), while conventional drying caused a gradient of 8% (b.u.). Regarding the color of the product in the different drying managements, drying with airflow inversion resulted in lighter products. For the microbiological analysis, fungi of the genera Cladosporium, Fusarium, and Aspergillus were found, among others. The average incidence of these fungi was higher in conventional drying samples than in fixed layer drying with inversion of airflow.

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Comparative study of mathematical and experimental models of coffee bean drying rate in a solar dryer simulator

Sihombing,

Ambarita,

Silalahi

2024

E3S Web Conf.

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The drying process of coffee beans requires heat energy to evaporate the moisture content in the material to be dried. Arabica coffee is dried at controlled temperatures (50°C, 60°C and 70°C) and wind speeds (0.4 m/s, 0.8 m/s and 1 m/s). The initial moisture content of the coffee bean test of 70% was dried to a moisture content of 11%. The drying air temperature is important for drying at high temperatures using a solar dryer simulator, which results in rapid moisture removal and reduced drying time. Drying was carried out to obtain the rate of reduction of moisture content experimentally compared to theoretically on mathematical models of drying agricultural products (Newton, Modified Henderson and Pabis and Modified Midili). Drying parameters are related to mass loss, temperature and humidity. From the results of the calculation of the experimental water content reduction rate with 3 formulas, the closest equation is Modified Midili.

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Mathematical Modelling and Immediate and Latent Quality of Natural Immature Coffee Under Different Drying Conditions

Cited by 5 publications

References 18 publications

Origin of black-green defect in the artificial drying of immature coffees

Origin of black-green defect in the artificial drying of immature coffees

Secador de camada fixa: uma adaptação para melhorar a secagem de café natural no Brasil

Comparative study of mathematical and experimental models of coffee bean drying rate in a solar dryer simulator

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