Coffee Science
URI permanente desta comunidadehttps://thoth.dti.ufv.br/handle/123456789/3355
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Item Quality of natural coffee dried under different temperatures and drying rates(Editora UFLA, 2018-04) Borém, Flávio Meira; Isquierdo, Eder Pedroza; Alves, Guilherme Euripedes; Ribeiro, Diego Egídio; Siqueira, Valdiney Cambuy; Taveira, Jose Henrique da SilvaThe final quality of coffees depends on the preservation of the cell membranes of the coffee beans, which can be damaged during the drying. Thus, the aim of this study was to assess the immediate and latent effects of the air temperature and drying rate on the sensorial quality of natural coffees, as well as its relationship with the chemical e physiological characteristics of the coffee beans. Mature fruits of arabica coffee were harvested and sundried to moisture content of approximately 35% (wb) and then moved into a mechanical drier under different conditions of drying. This process involved the combination of three dry bulb temperatures – DBT (35°C, 40°C, and 45°C) and two dew point temperatures – DPT (2.6°C and 16.2°C). Thus, the relative humidity of the air used for drying was a dependent variable of DTB and DPT, and as consequences, different drying rates were achieved for each DBT. The increase in the drying rate for the temperatures 35°C and 40°C has a negative effect on the final quality of natural coffee beans. However, for the temperature of 45°C, the effects of the drying rate on the coffee beans are overlaid by the thermal damages that are caused at this level of heating. Higher sensory scores for coffee are linked to lower values of electrical conductivity and potassium leaching of the exudate of the coffee beans, as well as lower values of fatty acids. It is emphasized that while the temperature of 35o C is recommended for the production of specialty coffees the temperature of 45o C is not.Item Drying kinetics of processed natural coffee with high moisture content(Editora UFLA, 2017-07) Siqueira, Valdiney Cambuy; Borém, Flávio Meira; Alves, Guilherme Eurípedes; Isquierdo, Eder Pedroza; Pinto, Afonso Celso Ferreira; Ribeiro, Diego Egídio; Ribeiro, Fabiana CarmaniniThe present study proposes a new processing and drying method and evaluates the behavior of grains subjected to this process through the water reduction rate and the adjustment of different mathematical models. Mature beans were divided into three batches. The first batch was continuously dried at 40±1 °C. The second batch consisted of natural coffee dried to moisture contents of 0.56±0.02, 0.41±0.02, 0,28±0.02 and 0.20±0.02 decimal (dry basis, d.b.), followed by processing and continuous drying at 35±1 oC and 40±1 oC. For all parcels, the drying process was ended when the coffee beans reached the moisture content level of 0.12±0.05 (d.b.). The third batch corresponded to the continuous drying of hulled and demucilated coffee at 40±1 °C. The experimental data were adjusted to ten mathematical models used to represent the drying of agricultural products. The grain water reduction rate was also evaluated. We concluded that the water reduction rate was highest for the drying temperature of 40±1 °C, especially at higher moisture contents. The total drying time for processed coffee with high moisture content was significantly reduced compared with the total drying time of natural coffee. The Midilli model satisfactorily describes the drying kinetics of processed coffee.