During coffee drying, different temperatures applied to the beans with varied humidity content levels can interfere in the membranes integrity, germination, organic acid and carbohydrate content resulting in coffees with distinct flavors. The quality control of the beans will be much more effective the earlier the alterations provoked in the postharvest are detected. This work has an objective to study alternative methods for the dehydration of the coffee beans using ultra-drying followed by slow drying and its impact on the sensorial quality, chemical composition and physiology. For that purpose, coffee lots were processed by the methods, dry (natural coffee) and wet (fully washed coffee); and sun-dried and machine-dried at a constant 60°C temperature and alternating 60/40°C. The sensory quality of the samples was assessed by the Specialty Coffee Association of America (SCAA) analysis protocol. The sugar, total titratable acidity and the phenolic compound content was also analyzed. The physiological alterations of the coffee beans were analyzed by germination tests, emergence speed index, electrical conductivity and potassium leaching. The temperature of the drying air significantly altered the sensorial quality of the coffee beans. The processing way associated to drying methods causes many physiological alterations with the highest damage observed in the natural coffees. For the first time, we are showing that drying with heated air at 60/40ºC is promising for the fully washed coffee beans, which are more tolerant to dehydration than the natural coffee beans. Conversely, the natural coffee beans were much more sensitive to drying regardless the temperature, with very low performance in the physiological analyses. The drying at the constant 60ºC temperature is inappropriate for the natural coffee as well as for the fully washed coffee beans. In addition, the physiological tests used were shown effective for the early evaluation of coffee beans quality.

RESUMOA manutenção da integridade das membranas celulares, entre outros eventos, é um forte indicativo de que a qualidade do café foi preservada na pós-colheita. Objetivou-se neste trabalho, analisar o efeito de diferentes métodos de secagem na manutenção da integridade da parede celular e da membrana plasmática de café natural e café despolpado, buscando determinar as condições e o momento em que ocorrem as rupturas microscópicas. Os cafés foram submetidos a um período de pré-secagem em terreiro. Após este, uma parcela de cada tipo de café foi desidratada no terreiro e, outra, à temperatura de 40ºC e 60ºC em secadores de camada fixa, monitorando-se a temperatura e o teor de água até 11% (bu). Nesse período, grãos foram aleatoriamente amostrados e fragmentos do endosperma preparados para a microscopia eletrônica de varredura, registrandose diversas eletromicrografias, avaliando-se as alterações na membrana plasmática da célula do endosperma dos grãos de cafés em função do teor de água e tempo de secagem. O citoplasma das células a 11% (bu) de teor de água não foi comprometido na secagem em terreiro e a 40°C; na secagem a 60°C, observou-se comprometimento nas estruturas celulares nos cafés com teor de água de 20% (bu).Termos para indexação: Café, processamento, secagem, microestrutura. ABSTRACTThe maintenance of the integrity of cellular membranes, among other events, is a strong indicator that the quality of the coffee was preserved in the post-harvesting process. Therefore, this work aimed to analyze the effect of different drying methods on the maintenance of the integrity of cell walls and plasma membrane of natural and de-pulped coffee in order to determine the conditions and the moment that microscopic ruptures take place. The coffee was submitted to a pre-drying period on a concrete patio. After this, a sample of each type of coffee was dehydrated outdoors and another, with heated air at 40ºC and 60ºC in fixed-layer dryers, controlling the grain temperature and the moisture content to 11% (bu). During the drying process the coffee grains were randomly sampled and fragments of the endosperm were prepared for scanning electron microscopy and eletromicrographs were taken. Measurements of the cells were taken for evaluating changes in the plasma membrane of the endosperm cells in relation to the moisture content and drying period. The cell cytoplasm of the coffee grains with 11% moisture content was not affected when dried under sun light and at the temperature of 40°C. When dried at 60°C, changes in the cellular structures of the cytoplasm were observed for coffees with moisture content of 20%.

RESUMOObjetivando-se estudar o efeito das lâminas de água, doses de nitrogênio e sua interação sobre os rendimentos produtivo e econômico da cultura da alface americana irrigada por gotejamento, conduziu-se um experimento em casa- de-vegetação Termos para indexação:Lactuca sativa L., Irrigação por gotejamento, Análise econômica. ABSTRACTThe main objective of this experiment carried out from September to December/2004, under greenhouse at the Federal University of Lavras, in Minas Gerais, was to study the effect of water and nitrogen applications rates, and the interaction between these factors on both the yieldand economics of crisphead lettuce. A 4 x 4 factorial experimental design with randomized blocks and three replications was used. Treatments were determined by combinations of four water depths (W 1 =91.99; W 2 =142.79; W 3 =186.34; W 4 =237.14 mm) and four nitrogen levels (N 0 =0; N 1 =80; N 2 =160; N 3 =320 kg ha -1 ). Crisphead lettuce (cv. raider) was grown under daily irrigations applications computed based on the evaporation measured on a reduced pan (EVm). Treatments W 1, , W 2 , W 3 e W 4 , corresponded to, respectively, 0.35EVm, 0.70EVm, 1.0EVm, and 1.35EVm. A 0.30 m x 0.30 m plant spacing was observed and irrigation water was applied trough a drip irrigation system with 1.6 L h 1 emitters spaced 0.30 m apart. Under the cost scenario considered, water at R$ 0.44 mm -1 , nitrogen at R$ 2.09 kg -1 and crisphead lettuce at R$ 0.80 kg -1 , the maxim profit, and the maxim economical productivity, estimated at 26,960 kg ha ).

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,...

No abstract

O objetivo deste trabalho foi avaliar os perfis proteicos e o desempenho fisiológico de sementes de café submetidas a diferentes métodos de processamento e secagem. Foram avaliados os processamentos por via seca e úmida, e as secagens natural, em terreiro, e artificial a 60ºC, ou a 60ºC até 30% de umidade e 40ºC até teor final de 11% (base úmida). Após serem processadas e secadas, as sementes foram avaliadas quanto ao desempenho fisiológico e submetidas a análises bioquímicas, por meio da eletroforese de proteínas resistentes ao calor LEA ("late embryogenesis abundant") e das enzimas superóxido dismutase, catalase, peroxidase, esterase, polifenoloxidase, isocitrato desidrogenase, álcool desidrogenase e malato desidrogenase. O perfil proteico de sementes de café é afetado pelo método de processamento e de secagem. Os cafés processados por via úmida apresentam maior tolerância à secagem - revelada pela maior atividade de enzimas antioxidativas e pelo melhor desempenho fisiológico - do que os processados por via seca. A atividade de proteínas resistentes ao calor e de enzimas antioxidantes é variável promissora para diferenciar a qualidade dos cafés submetidos a diferentes manejos pós-colheita.

No abstract

The present study was carried out to analyze chemical descriptors present in the raw coffee bean and to establish an association of these descriptors with the sensorial quality of the coffee beverage, based on expressions resulting from the interactions of coffee genotype, environment, and processing. The chemical descriptors caffeine, trigonelline, sucrose, and isomers of chlorogenic acid (3-CQA, 4-CQA, and 5-CQA), were analyzed through the use of high performance liquid chromatography (HPLC). Trained and qualified cuppers, certified as judges of specialty coffees, carried out the sensorial analysis using the methodology proposed by the Specialty Coffee Association of America (SCAA). Based on the cultivation environment, altitude and the genotype, it was possible to associate the chemical composition of the raw coffee bean with the coffee beverage sensorial quality. Yellow Bourbon cultivated above 1,200 m of altitude present higher contents of trigonelline and 3-CQA in the raw beans as well as high sensorial quality in the beverage.