Uso de perfis cromatográficos de voláteis de cafés arábicas torrados para a diferenciação das amostras segundo o sabor, o aroma e a qualidade global da bebida

Abstract

. In this work, the volatile chromatographic profiles of roasted Arabica coffees, previously analyzed for their sensorial attributes, were explored by principal component analysis. The volatile extraction technique used was the solid phase microextraction. The correlation optimized warping algorithm was used to align the gas chromatographic profiles. Fifty four compounds were found to be related to the sensorial attributes investigated. The volatiles pyrrole, 1-methyl-pyrrole, cyclopentanone, dihydro-2-methyl-3-furanone, furfural, 2-ethyl-5-methyl-pyrazine, 2-etenyl-n-methyl-pyrazine, 5-methyl-2-propionyl-furan compounds were important for the differentiation of coffee beverage according to the flavour, cleanliness and overall quality. Two figures of merit, sensitivity and specificity (or selectivity), were used to interpret the sensory attributes studied.Keywords: solid phase microextraction (SPME); coffee flavor; figures of merit. INTRODUÇÃOO aroma do café torrado é constituído por uma mistura complexa de compostos com poderes odoríferos distintos presentes em diferentes concentrações.1 De acordo com De Maria et al., 2 uma mesma substância volátil pode causar uma sensação odorífica agradável ou desagradável, dependendo de sua concentração no meio e das interações com outros compostos.Atualmente, a qualidade final da bebida do café é determinada pela "prova de xícara", realizada por provadores experientes. Dentre os atributos avaliados por estes profissionais encontram-se a qualidade global, o aroma e o sabor (bebida). Na "prova de xícara", considera-se o atributo "aroma" como a percepção olfativa dos gases liberados da infusão de café torrado e moído, enquanto o "sabor ou bebida" é considerado a combinação de sensações causadas pelos compostos químicos da bebida quando introduzida na boca. O atributo "qualidade global", por sua vez, é a percepção conjunta do sabor, do aroma e de outros atributos avaliados durante a análise.3 Estas definições acrescidas de resultados disponíveis na literatura indicam a elevada relação entre esses três atributos sensoriais da bebida. 4 Embora as pesquisas enfatizem que o aroma do café torrado tem um papel fundamental na qualidade da bebida, sendo considerado por muitos como sua impressão digital, são recentes os trabalhos que visam estabelecer essa relação. [4][5][6][7] Além disso, apenas alguns estudos são baseados na análise quimiométrica de dados cromatográficos com o propósito de tratar conjuntamente os constituintes voláteis do café e os resultados da "prova de xícara". 4,5,8 Os métodos quimiométricos são especialmente indicados para a aná-lise de cromatogramas de matrizes complexas, envolvendo centenas de compostos, da mesma forma que outros sinais instrumentais. A vantagem em se usar os perfís cromatográficos diretamente, ao invés de suas áreas de picos, é a possibilidade da extração de informações adicionais que não são computadas quando apenas as áreas são utilizadas como resposta analítica. Entretanto, para a aplicação das técnicas quimiométricas, os cromatogramas deve...

Relationship Between the Different Aspects Related to Coffee Quality and Their Volatile Compounds

“…Compounds from a wide variety of chemical classes, such as aldehydes (2‐butenal, 2‐methylpropanal*, 3‐methylbutanal, and 2‐methylbutanal*), acetic acid, ethers (1‐methoxy‐3‐methylbenzene and 2,4,6‐trichloroanisole), alcohols (dimethyl‐3‐octenol, 2‐methylisobutanol, 2‐methyl‐1‐propanol, 3‐methyl‐1‐butanol, 1‐octen‐3‐ol, 2‐nonanol, hexan‐1‐ol, 4,8a‐dimethyl‐decahydronaphthalen‐4a‐ol (geosmin), and 1,2,7,7‐tetramethylbicyclo[2.2.1]heptan‐2‐ol (2‐methylisoborneol), pyrazines (3‐isopropyl‐2‐methoxypyrazine* and 3‐isobutyl‐2‐methoxypyrazine*), ketones (1‐octan‐3‐one*, pentadecan‐2‐one), phenols (3‐methyl‐1‐methoxyphenol), thiols (dimethyl disulfide, and 2‐furfurylthiol*), hydrocarbons (methylbenzene, 1,3‐bis‐1,1‐dimethylethylbenzene, 7‐methyl‐3‐methylene‐1,6‐octadiene), and an ester (2,6‐bis‐(1,1‐dimethylethyl)‐4‐acetate) have been identified as responsible for negative notes in coffee. However, none of compounds mentioned has been associated with characteristic defects listed in the Official Brazilian Classification (COB), related to the type of drink or to microbial development in the seeds (Guyot and others ; Spadone and others ; Borjesson ; Cantergiani and others ; Morais and others ; Ribeiro and others ; Iamanaka and others ; Jackels and others ).…”

“…Ribeiro and others () evaluated the aromatic composition of different drink types (strictly soft, soft, rioy, and rio). The compounds 3‐methylbutanal, 2,3‐pentanedione*, and 4‐vinylguaiacol* were identified as volatile markers of high‐quality drinks (strictly soft and soft).…”

Exploratory and discriminative studies of commercial processed Brazilian coffees with different degrees of roasting and decaffeinated

“…The volatile compounds obtained from the roasted coffee headspaces, extracted with the two SPME fibres, were detected by GC-MS analysis and identified by comparing their fragmentations with the NIST data bank and some recently published papers (RIBEIRO et al, 2009(RIBEIRO et al, , 2010. This procedure was capable of extracting and detecting a large number of volatile compounds.…”

“…In the past, most chemometric analyses were performed on reduced data sets, only using the areas of selected peaks detected on the chromatograms. Currently this limitation can be overcome by using the entire chromatographic profiles via chemometric analyses (RIBEIRO et al, 2009(RIBEIRO et al, , 2010(RIBEIRO et al, , 2012.…”

Brazilian Coffee Blends: A Simple and Fast Method by Near‐Infrared Spectroscopy for the Determination of the Sensory Attributes Elicited in Professional Coffee Cupping

“…A number of studies, some of which involved a limited analysis of sensory attributes of coffees, were conducted to investigate the relationship between the sensory perception given by a cup of coffee (Lazim, & Suriani, 2009;Mendes, Menezes, Aparecida, & Silva, 2001;Monteiro, Minim, Silva, Chaves, & Cardello, 2005;Ribeiro et al, 2014;Ribeiro, Augusto, & Ferreira, 2010). However, this number is limited and does not involve a complete analysis of all sensory attributes recommended by SCAA in the "cupping test.…”