Capacidade redutora de bebidas de café preparadas com amostras comercializadas em Belo Horizonte-MG

• Ano de defesa: 2013
• Autor(a) principal: Azula Narayama Malacco Ferreira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Capacidade redutora; Folin-Ciocalteu; Café; Cafe; Analise colorimetrica; Colorimetria; Espectrofotometria; Antioxidantes
• Link de acesso: http://hdl.handle.net/1843/BUOS-9QTK4C

Coffee is one of the most consumed beverages worldwide and commonly present on Brazilian tables. It is known for its benefits for health, mainly because of its antioxidant compounds. Because of a lack of standardized analytical methods to evaluate these compounds in coffee, the variety of products sold, as well as the influence of the form of preparation of the beverage upon the content of the antioxidants, this work is intended to evaluate the reducing capacity of beverages prepared with samples of roasted and ground coffee sold in Belo Horizonte MG, as well as the influence of the preparation, employing the Folin Ciocalteu spectrophotometric method. After the optimization and validation of the method, the reducing capacity in commercial coffee beverages was evaluated as well as the influence of different ways of preparation, including infusion and decoction. The colorimetric analyses were made and the correlation between color parameters and reducing capacity in the samples was evaluated. Then, infrared analyses were done with the aim of finding the correlation between the reducing capacity results and the medium spectra obtained. The coffee samples presented different values in the reducing capacity. From the colorimetric analysis, the absence of colorimetric parameters correlation and the reducing capacity in commercial samples is seen. In contrast, when analyzing samples of 100% Arabica coffee roasted in specific conditions, a correlation was found among the colorimetric values, degree of roasting and reducing capacity. In this context, it can be concluded that the lack of standardization in the roasting processes of commercial coffee, as well as the influence of the composition of the blends in response to the roasting process, result in the absence of correlation between the colorimetric parameter and reducing capacity. Considering the 100% Arabica coffee samples roasted in the laboratory, the increase of the roasting degree was followed by an increase in the reducing capacity of the coffee probably because of a major formation of the reducing compounds during the roasting process. This trend was not found in commercial coffee. Finally, in the infrared analyses a qualitative correlation was found between the reducing capacity values and the normalized medium spectra and in bands between 2300 and 1800cm-1 and 1800 and 1640cm-1 obtained from the 100% Arabica coffee samples roasted under specific conditions. The great variability of the results in the reducing capacity and colorimetry obtained in the commercial coffee can be explained by the variety of coffee used in the blends production, the same was with the different roasting techniques of each variety. Besides, the preparation technique influences the final reducing capacity necessitating more studies of different preparation techniques, and more knowledge about consumer habits and preferences.