AlteraÃÃes quÃmicas, sensoriais e microscÃpicas do cafà cereja descascado em funÃÃo da taxa de remoÃÃo de Ãgua / Chemical, sensorial and microscopic alterations of the peeled coffee cherry as related with water removal rate

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

This work was intended to evaluate the effect of different temperatures and pre-drying periods on yard on the drying time, rate of water reduction, on the chemical composition, the quality of the beverage of coffee and cell alterations in the structure of the membranes and cell walls of the endosperm of peeled cherry coffee beans. The coffee was submitted to two pre-drying times, 1 and 3 days on yard. After the pre-drying, the produce was submitted to drying in three experimental dryers with fixed layer of 13 cm in thickness, by using three average temperatures in the coffee mass 40ÂC, 50ÂC and 60ÂC with an air flow of 20m3 m-1 m-2 with four replicates in time. In the dryers, for monitoring of water loss and attainment of the drying curves, the samples were weighed every 1 hour. Drying stopped when the coffee reached the mass corresponding to 11% of moisture (bu). The temperatures of the coffee mass were measured every 30 minutes. In addition to the drying curves, curves of water reduction rates were obtained. It was observed that the drying time diminished as both temperature and the period of pre-drying increased and that the water removal rate was lesser for the temperature of 40ÂC and 3 daysâ pre-drying. For evaluation of quality, the following analyses were accomplished electrical conductivity, potassium leaching, fatty acidity, total sugars, reducing and non-reducing sugars and sensorial analyses. It was found that electrical conductivity, potassium leaching and fatty acidity increased significantly as temperature was risen. The increase in the pre-drying period caused reduction in the potassium leaching and increases in the values of reducing sugars. The 3-day pre-drying period enabled the obtaining of a beverage of superior quality in relation to one-day pre-drying.In the histochemical and ultra-structural analyses to evaluate alterations in the plasmatic membrane, it was possible to observe in the beans dried at 40ÂC, the maintenance of the compartmentalization of the oil corpuscles, which presented themselves distributed uniformly all over the internal perimeter of the membrane; the space between the plasmatic membrane and cell wall (lumen) proved empty. In contrast, in the coffee beans dried at 60ÂC, the fusion of the oil corpuscles making up large oil drops in the intercellular space with the total fulfilling the cell lumen, denoting the rupture of the plasmatic membrane and the rupture and coalescence of the cell vesicles.

ASSUNTO(S)

quality drying secagem microscopia qualidade microscopic ciencia de alimentos

ACESSO AO ARTIGO

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