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Contributo para o estudo da qualidade do grão de café da Gorongosa
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Resumo(s)
O estudo da qualidade do café é de extrema importância dado que constitui uma das bebidas mais consumidas no mundo. Esta dissertação teve assim, como objetivo, o estudo de três parâmetros de qualidade do café: teor de cafeina, potencial antioxidante e contaminação por ocratoxina A, em amostras de café arábica verde e torrado. Este trabalho envolveu uma revisão bibliográfica sobre os trabalhos publicados neste domínio, a nível mundial, na última década.
Os estudos analisados revelaram uma variação dos teores de cafeína em café verde e torrado, entre 0,8 – 38,5 g/kg e 1,3 – 9,9 g/kg, respetivamente, apresentando, no geral uma boa estabilidade térmica. Contudo, esta pode ser afetada pela torra. A concentração de cafeína pode ainda depender das condições em que o cafeeiro se desenvolve, o que poderá explicar a grande variabilidade de teores encontrados.
Quanto à atividade antioxidante, registaram-se grandes variações (62,2 – 71,3%) em grãos verdes provenientes de diferentes origens geográficas, o que evidencia a importância da origem do café. Quanto aos compostos fenólicos totais, estes geralmente diminuem com a torra, variando na gama de concentrações 5,2 – 220,0 g de ácido gálico equivalentes (GAE)/kg e 7,9 – 151,4 g GAE/kg para o café verde e torrado, respetivamente. Contrariamente a esta tendência, registaram-se aumentos da atividade antioxidante em graus de torra reduzidos, provavelmente atribuídos à formação de melanoidinas, com capacidade antioxidante.
Relativamente à contaminação de café por OTA, foram registados valores entre 5,8 e 247,0 μg/kg para café verde e 1,99 e 115,0 μg/kg para café torrado, nas regiões da América e Ásia. O café verde apresentou valores mais elevados de OTA em comparação com o café torrado confirmando-se a redução dos teores de OTA pelo processo de torra.
De entre os grãos defeituosos, os grãos com defeito “preto” da região da América foram os que registaram maior contaminação de OTA (25,7 μg/kg).
The study of coffee quality is extremely important since it is one of the most consumed beverages in the world. The objective of this dissertation was to study three parameters of coffee quality: caffeine content, antioxidant potential and ochratoxin A contamination in green and roasted Arabica coffee samples. This work involved a literature review on the works published in this field worldwide in the last decade. The analysed studies revealed a variation in caffeine content in green and roasted coffee, between 0.8 – 38.5 g/kg and 1.3 – 9.9 g/kg, respectively, generally presenting good thermal stability. However, this may be affected by roasting. The caffeine concentration may also depend on the conditions in which coffee develops, which may explain the great variability of levels found. Regarding antioxidant activity, there were large variations (62.2 - 71.3%) green beans from different geographical origins, which highlights the importance of the origin of coffee. As for total phenolic compounds, these generally decrease with roasting, ranging in range of concentrations 5.2 – 220.0 g of equivalent cholic acid (GAE)/kg and 7.9 – 151.4 g GAE/kg for green and roasted coffee, respectively. Contrary to this trend, there were increases in antioxidant activity in reduced degrees of roasting, probably attributed to the formation of melanoidins, with antioxidant capacity. Regarding coffee contamination by OTA, values between 5.8 and 247.0 μg/kg for green coffee and 1.99 and 115.0 μg/kg for roasted coffee in the regions of America and Asia were recorded. Green coffee showed higher OTA values compared to roasted coffee confirming the reduction of OTA contents by roasting process. Among the defective grains, the "black" defective grains of the Region of America were the ones with the highest OTA contamination (25.7 μg/kg).
The study of coffee quality is extremely important since it is one of the most consumed beverages in the world. The objective of this dissertation was to study three parameters of coffee quality: caffeine content, antioxidant potential and ochratoxin A contamination in green and roasted Arabica coffee samples. This work involved a literature review on the works published in this field worldwide in the last decade. The analysed studies revealed a variation in caffeine content in green and roasted coffee, between 0.8 – 38.5 g/kg and 1.3 – 9.9 g/kg, respectively, generally presenting good thermal stability. However, this may be affected by roasting. The caffeine concentration may also depend on the conditions in which coffee develops, which may explain the great variability of levels found. Regarding antioxidant activity, there were large variations (62.2 - 71.3%) green beans from different geographical origins, which highlights the importance of the origin of coffee. As for total phenolic compounds, these generally decrease with roasting, ranging in range of concentrations 5.2 – 220.0 g of equivalent cholic acid (GAE)/kg and 7.9 – 151.4 g GAE/kg for green and roasted coffee, respectively. Contrary to this trend, there were increases in antioxidant activity in reduced degrees of roasting, probably attributed to the formation of melanoidins, with antioxidant capacity. Regarding coffee contamination by OTA, values between 5.8 and 247.0 μg/kg for green coffee and 1.99 and 115.0 μg/kg for roasted coffee in the regions of America and Asia were recorded. Green coffee showed higher OTA values compared to roasted coffee confirming the reduction of OTA contents by roasting process. Among the defective grains, the "black" defective grains of the Region of America were the ones with the highest OTA contamination (25.7 μg/kg).
Descrição
Mestrado em Engenharia Alimentar. Universidade de Lisboa, Instituto Superior de Agronomia
Palavras-chave
café arábica torra cafeína potencial antioxidante ocratoxina A arabica coffee roasting caffeine antioxidant potential ochratoxin A
Contexto Educativo
Citação
Silva, J.M.D. Contributo para o estudo da qualidade do grão de café da Gorongosa. Lisboa: ISA-Universidade de Lisboa, 2021. Dissertação de Mestrado
Editora
Instituto Superior de Agronomia, Universidade de Lisboa