Avaliação de diferentes métodos de secagem do café (coffea arabica l.) cereja descascado

• Autor(a) principal: Ampessan, Fernando
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3555
• topic: Café; Secagem; Pós-colheita; Coffee; Drying; Post-harvest; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA

Drying is one of the operations of pre‐processing that may influence the maintenance of coffee quality. Consists of the removal of water excess in coffee, till a safe value for storage (10 a 12% b.u.). The artificial drying in terraces is the main process used in Brazil, but the use of mechanical dryers is increasing due to new techniques of drying and more economic and rentable dryers. Therefore, in this work the objective was to analyze and compare different techniques of drying considering the quality, specific energy consumption and operational costs. In the drying in terraces analysis were evaluated different materials of pavements, asphalt, concrete and suspended terrace; taking into consideration the weather, global solar radiation, reflected, the speed of wind, the temperatures of the berries, surface of the terrace covered by the berries and exposed to solar radiation. The level of water was monitored daily, at 9am, 12pm and 3pm. In the mechanical drying were analyzed two systems: a) combined drying (pre‐drying in terrace of concrete and additional drying in hybrid dryer) and; b) complete drying in hybrid dryer. The temperatures in different points of the berries and in the dryer plenum were monitored, besides the local weather conditions. The level of water was monitored each hour and the berries were revolved in intervals of two hours. Samples of dried coffee were sent to the Laboratory of Mycology and Pathology of Seeds of the Department of Plant Pathology at Federal University of Viçosa for the detection and identification of fungus. Samples were also sent to the company Corretora Três Irmãos Ltda, located at Viçosa, for classification. The drying time in terrace of asphalt were in 13 days, in the suspended terrace 14 days, and in the terrace of concrete was 15 days. The complete drying in hybrid dryer was carried out in 66 hours, and the completion of combined drying, in the hybrid dryer, was carried out in 36 hours, and the initial level of water was 32,4% (b.u.). The final level varied between 11,9 e 11,7 % (b.u.), respectively. The specific energy consumption for the terrace of asphalt was 9,4640 MJ.kg‐1 of evaporated water; for terrace of concrete was 10,6462 MJ.kg‐1. In the complete drying in hybrid dryer and in the combined system was, respectively, 7,5478 e 9,3384 MJ.kg‐1 of evaporated water. It was observed that the coffee was contaminated, in field, by microorganisms. The minor level of contamination was observed in the product dried in hybrid dryer. The operational costs for drying, per bag of 60kg, were R$11,12 for dried in terrace of asphalt; R$14,13 for terrace of concrete; R$20,21 for combined system; and R$11,09 for complete drying. It was concluded that the drying in asphalt terrace is faster than in concrete terrace. For the same level of water, it was observed less time of the process when the coffee was completed dried in the hybrid dryer, compared to the combined system. The drying in terrace of asphalt was more efficient in terms of energy than in the terrace of concrete, for the same experimental conditions. The complete drying in hybrid dryer was more efficient in terms of energy than the combined drying and drying in terraces, independently if it is made by concrete or asphalt. Fixed bed‐ dryers provide reduction in infection by some species of fungi, both in green coffee as parchment. The hybrid dryer has the minor operational cost. About the components of costs of drying, the cost of labor force represent greater proportion of the total cost to the drying terrace. In the complete drying in hybrid dryer a better quality drink is gotten. There was no influence of the terrace on the quality of coffee beverage.