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

Abstract

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.

Eficiência térmica do coletor solar plano durante a secagem do café (Coffea arabica L.) sob diferentes condições climáticas

“…Pesquisas foram desenvolvidas em forno com circulação de ar forçada a 40 oC (BOTELHO et al, 2016) e 45 ± 2 oC (MUSEMBI et al, 2016), fornalha de fogo indireto com variação entre 10 a 50 oC (OLIVEIRA et al, 2020) e secador de camada fixa nas temperaturas de 35, 40 e 45 oC (ISQUIERDO et al, 2013). A temperatura do ar de secagem influencia na taxa de secagem e, por consequência, na qualidade sensorial do café despolpado.…”

“…Dentre as etapas de pós-colheita do grão, o processo de secagem pode ser considerado com um dos mais importantes por afetar diretamente a qualidade de bebida e, consequentemente competitividade no mercado (OLIVEIRA et al, 2020;MOREIRA et al, 2019;SILVIA et al, 2019). Normalmente, a secagem do café é feita por meio do processo natural em terreiros a céu aberto ou secadores mecânicos.…”

“…Normalmente, a secagem do café é feita por meio do processo natural em terreiros a céu aberto ou secadores mecânicos. No entanto, devido a desvantagens como riscos de contaminação por agentes físicos e biológicos, paralisação do processo em período de chuvas, longos períodos de secagem em terreiros, elevado custo e demanda energética de combustíveis fósseis, que acarretam em risco ao ambiente e a saúde dos trabalhadores e dependência energética em secadores mecânicos, pesquisas vem sendo desenvolvidas a fim de se obter técnicas eficientes com resultado final na qualidade de bebida (OLIVEIRA et al, 2020;MOREIRA et al, 2019). Ainda, tem-se a necessidade de estudos sobre a secagem do café processado de diferentes formas, pois o café processado via seca é mais sensível à secagem mecânica com ar aquecido do que o processado via úmida (ALVES et al, 2017).…”

Physicochemical and Sensory Properties of Arabica Coffee Beans of Arara cv. Dried Using Different Methods

“…Combinations of these methods can also be used, where the coffee is initially exposed to the sun and then subjected to mechanical drying, typically at temperatures below 40 °C. This is because various studies have shown that higher temperatures can damage the quality of the coffee [ 10 , 11 ]. Drying at temperatures above 40 °C can lead to physical and chemical damage to the coffee beans, resulting in loss of aroma and flavor, weight loss, and deterioration of the quality of the final product [ 12 ].…”