Identificação de cultivares de café por meio da avaliação multivariada da composição química dos grãos torrados. II - Distância de Mahalanobis e distância quadrática
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2007
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Resumo
O objetivo deste trabalho foi utilizar a composição química de grãos torrados de 16 cultivares de cultivares de Coffea arabica L, para identificar semelhanças entre esses materiais genéticos. Os frutos foram colhidos na Fazenda Experimental de Varginha, do PROCAFÉ/MAPA, localizado na região Sul de Minas Gerais, na safra 2002/2003. As amostras foram preparadas no Pólo de Tecnologia em Pós-Colheita do Café da UFLA, sendo lavados, descascados e secados em terreiro de concreto. Após o beneficiamento, os grãos foram acondicionados em latas de alumínio e armazenados à 15 oC. Para as avaliações os cafés foram torrados em torra clara e em seguida foram moídos. Avaliaram-se 13 parâmetros físico-químicos nos grãos torrados e os dados foram submetidos ao software SAS para calcular a Distância de Mahalanobis como medida da similaridade e a partir desta, um dendograma foi construído usando o método da distância do vizinho mais próximo. Não houve separação das cultivares pela distância de Mahalanobis, o que pode ser uma conseqüência do efeito da torração sobre as variáveis estudadas. Avaliou-se também a distância quadrática entre as amostras, que permite observar se a distância que as separa é significativa ou não. Pela avaliação da distância quadrática, observou-se que a cultivar Canário foi a que mais divergiu do grupo, sendo encontradas distâncias significativas entre ela e outras 10 cultivares. Ambas as medidas de similaridades utilizadas nesse trabalho, não foram efetivas para promover a separação das cultivares, podendo considerar que os grãos de café das 16 cultivares avaliadas, quando torrados apresentam uma grande semelhança na composição química.
The objective of this work was to use the chemical composition of roasted grains of 16 cultivars of Coffea arabica L., to identify similarities among those genetic materials. The fruits were picked in experimental Farm of Varginha, of PROCAFÉ / MAPA, located in the South of Minas Gerais, in the harvest 2002/2003. The samples were prepared in the Postharvest Technology Center of Universidade Federal de Lavras, were they washed, peeled and dried at concrete yard. After the improvement, the grains were conditioned in cans of aluminum and stored to 15 oC. For the evaluations the coffees were toasted in it roasts egg white and soon afterwards they were ground. Thirteen physiochemical parameters were evaluated in the toasted grains and the data were submitted to the SAS software to calculate the Distance of Mahalanobis as measure of the similarity and starting from this, a dendograma was built using the method of the closest neighbor's distance. There was not separation of the cultivars for the distance of Mahalanobis, what can be a consequence of the effect of the roasted on the studied variables. It was also evaluated the quadratic distance among the samples, that it allows to observe the distance that separates is them significant or not. For the evaluation of the quadratic distance, it was observed that was what more diverged of the group to cultivar Canario, being found significant distances among her and other 10 cultivar. Both measures of similarities used in that work, they didn't go effective to promote the separation of the cultivar, could consider that the coffee beans of the 16 cultivars appraised, when roasted present a great similarity in the chemical composition.
The objective of this work was to use the chemical composition of roasted grains of 16 cultivars of Coffea arabica L., to identify similarities among those genetic materials. The fruits were picked in experimental Farm of Varginha, of PROCAFÉ / MAPA, located in the South of Minas Gerais, in the harvest 2002/2003. The samples were prepared in the Postharvest Technology Center of Universidade Federal de Lavras, were they washed, peeled and dried at concrete yard. After the improvement, the grains were conditioned in cans of aluminum and stored to 15 oC. For the evaluations the coffees were toasted in it roasts egg white and soon afterwards they were ground. Thirteen physiochemical parameters were evaluated in the toasted grains and the data were submitted to the SAS software to calculate the Distance of Mahalanobis as measure of the similarity and starting from this, a dendograma was built using the method of the closest neighbor's distance. There was not separation of the cultivars for the distance of Mahalanobis, what can be a consequence of the effect of the roasted on the studied variables. It was also evaluated the quadratic distance among the samples, that it allows to observe the distance that separates is them significant or not. For the evaluation of the quadratic distance, it was observed that was what more diverged of the group to cultivar Canario, being found significant distances among her and other 10 cultivar. Both measures of similarities used in that work, they didn't go effective to promote the separation of the cultivar, could consider that the coffee beans of the 16 cultivars appraised, when roasted present a great similarity in the chemical composition.
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
Café torrado Composição química Qualidade Cultivares, Roasted coffee Chemical composition Quality Cultivars
Citação
Mendonça, Luciana Maria Vieira Lopes; Pereira, Rosemary Gualberto Fonseca Alvarenga; Borém, Flávio Meira; Ferreira, Daniel Furtado; Mendonça, José Marcos Angélico de. Identificação de cultivares de café por meio da avaliação multivariada da composição química dos grãos torrados. II - Distância de Mahalanobis e distância quadrática. 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.