Quality of Natural Coffee Dried Under Different Temperatures and Drying Rates

Abstract

ABSTRACT:The 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.Index terms: Sensory analysis, specialty coffees, relative humidity, dew point temperature. QUALIDADE DO CAFÉ NATURAL SUBMETIDO A DIFERENTES TEMPERATURAS E TAXAS DE SECAGEM RESUMO:A qualidade do café depende da preservação das membranas celulares dos grãos, que podem ser afetadas durante a secagem. Assim, este estudo foi realizado com o objetivo de avaliar os efeitos imediatos e latentes da temperatura do ar e da taxa de secagem na qualidade sensorial do café natural e sua relação com as características químicas e fisiológicas dos grãos. Frutos maduros de café arábica foram colhidos e secos ao sol até atingirem a umidade de aproximadamente 35% (b.u.) e então transferidos para um secador mecânico, onde foram submetidos a diferentes condições de secagem, obtidas pela combinação entre três temperaturas de bulbo seco (TBS), 35°C, 40°C e 45°C e duas temperaturas de ponto de orvalho (TPO), 2,6°Ce16,2°C. Assim, a umidade relativa do ar de secagem constituiu-se como uma variável dependente da TBS e da TPO e como consequência da umidade relativa obtiveram-se diferentes taxas de secagem para cada TBS. A análise dos dados indicou que, o aumento na taxa de secagem para as temperaturas de 35°C e 40°C tem efeito negativo na qualidade do café natural. Já para a temperatura de 45ºC, os efeitos da taxa de secagem na qualidade do café natural são sobrepostos pelos danos térmicos que predominam nessa temperatura. Notas sensoriais mais elevadas para o café estão associadas com valores mais baixos de condutividade elétrica,...

Colour variation in immature coffee dried under different dry bulb and dew point temperature conditions

“…°C is the recommended maximum air temperature for ripe coffee berries, and 45 °C exceeds the recommended temperature for drying quality coffee (Borém et al, 2018).…”

Qualidade sensorial do café submetido a secagem a baixa temperatura e a frio com emprego de um sistema baseado em tecnologia de bomba de calor

“…Diferente de outros produtos agrícolas, o preço do café é determinado pela sua qualidade sensorial (Zaidan et al, 2017;Borém et al, 2018). Desta forma, há uma oportunidade para aumentar o valor do produto em função do aumento ou manutenção da Development, v. 9, n. 11, e59791110302, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.10302 qualidade da bebida, possibilitando novos investimentos em tecnologias nesta área (Donovan et al, 2019).…”

Designing An Automatic Microcontroller-based Drying Machine of Coffee Beans

“…The deficiency is that the humidity and temperature sensors experienced more errors when the received temperature exceeds the room temperature that, in general, reaches 45°C. The final quality of coffee depends on the curing of the cell membrane of coffee beans, which might get deteriorated during the drying process [10] . For the drying temperature set at 35°C, the increasing drying rate caused the degradation of the coffee's natural sensory quality.…”

“…For the drying temperature set at 35°C, the increasing drying rate caused the degradation of the coffee's natural sensory quality. For the drying temperature set at 45°C, the drying rate's degradation is described by thermal decay and the effect of unclear drying rate [10] . The farmers will no longer have to use the traditional method if they use this coffee bean drying machine.…”