Variações na área das células do endosperma durante a secagem de cafés (Coffea arabica L.) naturais e despolpados
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Data
2007
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Resumo
A 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. Cafés despolpados e cafés em sua forma natural foram submetidos ao processo de secagem em terreiro e secagem com ar aquecido a 40 e 60ºC. Durante a secagem, grãos foram aleatoriamente amostrados e fragmentos do endosperma preparados para a microscopia eletrônica de varredura, no aparelho LEO EVO 40 XVP. Foram geradas e registradas digitalmente diversas imagens para cada amostra. Nas eletromicrografias geradas, foram feitas medições nas células, avaliando-se as alterações na membrana plasmática bem como as variações da área celular em função do teor de água e do tempo de secagem. A partir dos resultados obtidos pode-se concluir que a variação na área das células do endosperma do café depende do tipo de processamento usado e das condições de secagem, entretanto, o fenômeno da contração e expansão diferenciou-se na intensidade e momento de ocorrência. Essas oscilações podem estar relacionadas com o comprometimento da integridade da membrana plasmática. A maior taxa de variação do citoplasma foi observada na secagem à temperatura de 60ºC, na fase intermediária, na qual o teor de água encontrou-se entre 30% e 20% (b.u.).
The maintenance of the integrity of the cellular membranes, among other events, is a strong indicator that the quality of the coffee was preserved after harvesting. Therefore, this work aimed to analyze the effect of different drying methods in the maintenance of the integrity of the 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. De-pulped and natural coffees were submitted to the drying process under sun light and with heated air at 40 and 60ºC. During drying coffee grains were randomly sampled and fragments of the endosperm were prepared for scanning electronic microscopy using the equipment LEO EVO 40 XVP. For each sample images were generated and registered digitally. In the electromicrographs generated were performed measurements in the cells, evaluating changes in the plasma membrane as well as variations in the cellular area in function of the water content and period of drying. From the results obtained we concluded that the variation in the cellular area of the coffee endosperm depends on the type of processing method and the drying conditions used, albeit the phenomenon of cell contraction and expansion differed in intensity and moment of occurrence. Those changes can be related to the changes in plasma membrane integrity. The largest rate of variation of the cytoplasm was observed when the grains were dried the temperature of 60ºC, in the intermediate phase, with water content of 30% and 20%.
The maintenance of the integrity of the cellular membranes, among other events, is a strong indicator that the quality of the coffee was preserved after harvesting. Therefore, this work aimed to analyze the effect of different drying methods in the maintenance of the integrity of the 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. De-pulped and natural coffees were submitted to the drying process under sun light and with heated air at 40 and 60ºC. During drying coffee grains were randomly sampled and fragments of the endosperm were prepared for scanning electronic microscopy using the equipment LEO EVO 40 XVP. For each sample images were generated and registered digitally. In the electromicrographs generated were performed measurements in the cells, evaluating changes in the plasma membrane as well as variations in the cellular area in function of the water content and period of drying. From the results obtained we concluded that the variation in the cellular area of the coffee endosperm depends on the type of processing method and the drying conditions used, albeit the phenomenon of cell contraction and expansion differed in intensity and moment of occurrence. Those changes can be related to the changes in plasma membrane integrity. The largest rate of variation of the cytoplasm was observed when the grains were dried the temperature of 60ºC, in the intermediate phase, with water content of 30% and 20%.
Descrição
Trabalho apresentado no Simpósio de Pesquisa dos Cafés do Brasil (5. : 2007 : Águas de Lindóia, SP). Anais. Brasília, D.F. : Embrapa Café, 2007.
Palavras-chave
Contração celular Membrana celular Microscopia de varredura, Cellular contraction Cellular membrane Scanning microscopy
Citação
Borém, Flávio Meira; Saath, Reni; Alves, Eduardo; Taveira, José Henrique. Variações na área das células do endosperma durante a secagem de cafés (Coffea arabica L.) naturais e despolpados. In: Simpósio de Pesquisa dos Cafés do Brasil (5. : Águas de Lindóia, SP : 2007). Anais. Brasília, D.F. : Embrapa - Café, 2007. (1 CD-ROM), 5p.