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Master's Dissertation
DOI
https://doi.org/10.11606/D.11.2020.tde-24032020-094916
Document
Author
Full name
Gabriela Maria Rodrigues do Nascimento de Alcantara
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2019
Supervisor
Committee
Mattos, Wanessa Melchert (President)
Rocha, Fabio Rodrigo Piovezani
Sato, Mariana Roberto Gama
Souza, Rodrigo Aparecido Moraes de
Title in Portuguese
Comparação das espécies químicas não voláteis entre cafés especiais e tradicionais
Keywords in Portuguese
Cafés
Cafés especiais
Compostos não voláteis
Perfil cromatográfico
Abstract in Portuguese
O café é uma das bebidas mais consumidas no mundo e de alto valor econômico. As duas espécies mais comercializadas são Coffea arabica e Coffea canephora, sendo que a primeira tem maior valor comercial e qualidade sensorial. O segmento de mercado para cafés vem se expandido. Os cafés especiais referem-se aos cafés de mais alta qualidade que apresentam, após a torra, atributos especiais na prova da xícara e altas pontuações. O grão de café apresenta na constituição diferentes compostos voláteis e não voláteis que são os responsáveis pelos atributos de sabor e aroma; o consumo da bebida também está associado a uma série de benefícios para saúde, como a atividade antioxidante. O objetivo do trabalho foi avaliar a composição química das espécies não voláteis de cafés especiais e tradicionais e correlacionar a qualidade da bebida com os parâmetros sensoriais. Foram analisadas 17 amostras, sendo 8 de cafés especiais da região Alta Mogiana da espécie Coffea arabica e 9 de cafés tradicionais adquiridos no comércio local. Determinação da atividade antioxidante para as amostras foram realizadas pelos métodos DPPH e ABTS e os compostos fenólicos totais foram determinados pelo método de Folin-Ciocalteau. A composição química dos compostos não voláteis foi avaliada por Cromatografia Líquida de Alta Eficiência. Os compostos identificados foram cafeína, ácido clorogênico, ácido cafeico e ácido nicotínico para as amostras de cafés especiais e tradicionais e o composto 5-hidroximetilfurfural identificado somente para cafés especiais. Os cafés especiais apresentaram níveis maiores para ácido clorogênico, ácido cafeico e 5-hidroximetilfurfural, sendo compostos associados aos atributos de aroma e sabor do café, contribuindo para as características únicas de cada amostra assim classificada. A ausência dos compostos 5-hidroximetilfurfural e os baixos teores de ácido clorogênico e ácido cafeico nos cafés tradicionais sugerem que esses cafés sofreram torrefação acentuada, o que contribuiu para a degradação dos compostos e também para a perda de características sensoriais. O alto teor de cafeína para esses cafés indica formulação de blends em maior parte constituída por café robusta, espécie essa de menor qualidade em relação à arábica. Com as análises dos componentes principais foi possível estabelecer relação entre os teores dos compostos quantificados com a classificação em especial e tradicional, com as notas sensoriais para o café especial e a relação entre a atividade antioxidante e as concentrações dos compostos fenólicos.
Title in English
Comparison of non-volatile chemical species between special and traditional coffees
Keywords in English
Chromatographic profile
Coffees
Non-volatile compounds
Special coffees
Abstract in English
Coffee is one of the most consumed drinks in the world, besides having a high economic value. The most sold species are Coffea arabica and Coffea canephora, and the former has a higher commercial value and sensory quality. The market segment for coffees is expanding. The special coffees concern products that present a higher quality after roasting, special attributes when tasting, and high scores. The coffee bean presents different volatile and non-volatile compounds in its formation, which are responsible for flavor and aroma attributes, and its consumption is also associated with a lot of health benefits, such as antioxidant activity. The aim of this study was to evaluate the chemical composition of non-volatile species of special and traditional coffees and correlate their quality according to sensorial parameters. 17 samples were analyzed: 8 special coffees from the region of Alta Mogiana, the Coffea arabica species, and 9 traditional coffees acquired at the local market. Determinations of the antioxidant activity were carried out through the DPPH and ABTS methods and total phenolic compounds were determined through the Folin-Ciocalteau method. The chemical composition of the non-volatile compounds was studied by high performance liquid chromatography. The identified compounds were caffeine, chlorogenic acid, caffeic acid and nicotinic acid for special and traditional coffee samples, and the 5-hydroxymethylfurfural compound was identified only in special coffees. The special coffees presented higher levels of chlorogenic acid, caffeic acid, and 5-hydroxymethylfurfural, which are associated with coffee flavor and aroma attributes contributing for unique characteristics of each classified sample. The absence of 5-hydroxymethylfurfural compounds and the low level of chlorogenic acid and caffeic acid in traditional coffees suggest that these coffees went through steep roasting, which contributes for the compounds degradation and also for the loss of sensorial characteristics. The high level of caffeine for these coffees indicates formulation of blends and, mostly, it is formed by the robust coffee, which is a species that shows lower quality compared to the arabic one. By analyzing the main compounds, it was possible to correlate the levels of the quantified compounds and classification as special or traditional; a link between the levels of the quantified species and sensorial notes for the special coffee; and a link between the antioxidant activity and the concentrations of phenolic compounds.
 
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Publishing Date
2020-04-29
 
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