Relação entre qualidade, rastreabilidade e compostos voláteis de grãos de café arábica torrados de diversas regiões brasileiras
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Data
2018-02-20
Autores
Toledo, Paulo Roberto Aparecido Bueno de [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A qualidade do café e sua peculiaridade é intrinsicamente dependente de diversos fatores, dentre eles espécies/cultivares, origem geográfica, tipos dos grãos, colheita, processamento pós-colheita, torrefação e armazenamento. No presente trabalho revela-se a complexidade da relação entre a qualidade e composição aromática do café. Muitos aspectos abordados continuam sem ser totalmente elucidados, dentre eles, origem geográfica e processamento pós-colheita, enquanto outros, podem ser melhor compreendidos, tais como influência de espécies, qualidade de grãos e condições de armazenamento. No presente estudo alguns aspectos tais como origem geográfica, tipos dos grãos e torrefação foram avaliados e correlacionados através da composição volátil utilizando-se ferramentas de análise multivariada. Em todos os casos foram analisadas a composição volátil dos grãos de café através da técnica de Headspace-SPME. A correlação entre compostos voláteis e os fatores analisados foi constatada e, permitindo-se assim a elaboração de modelos discriminantes para a diferenciação de amostras de diferentes origens geográficas, grau de torrefação e selos de qualidade (tipos de grãos). Identificou-se também compostos voláteis marcadores de origem geográfica (macrorregiões e microrregiões), grau de torração e qualidade dos grãos. Dentre os marcadores voláteis encontrados no estudo o 2-metilbutanal é o marcador mais versátil, por ser considerado importante em todos os testes de discriminação geográfica, compostos como a 2-etilpirazina e 2,5-dimetilpirazina são importantes marcadores para ambas as avaliações de origem geográfica e de grau de torrefação. Do ponto de vista sensorial, estes dois compostos estão ligados a notas sensoriais de amendoim e avelã torrada. Os modelos propostos foram validados através de validação cruzada e testes de permutação. Os modelos propostos são de grande importância para o controle de qualidade e rastreabilidade de cafés torrados e, contribuem como alternativas não subjetivas de controle de qualidade de amostras de café. Também foi realizada uma revisão da literatura utilizando a técnica de extração supercrítica aplicada em diversas etapas do processamento do café, além disso, foi realizada também a otimização de parâmetros experimentais de SFE focado na obtenção de extratos ricos em compostos aromáticos, as melhores condições para maximizar a extração de óleos aromáticos foram 180 bar / 80 °C / 0% de etanol, que levaram a perfis aromáticos ricos de uma gama variada de classes químicas nomeadamente aldeídos, fenóis, cetonas e dicetonas, piridinas, pirazinas, ácidos carboxílicos, ciclopentenos, furanos, pirróis, álcoois e ésteres. Consequentemente, os parâmetros de processos específicos encontrado neste estudo (temperatura de 80 ° C e pressão de 180 bar) podem então ser aplicados para produção em escala industrial visando a produção de extratos de café ricos em compostos aromáticos. Desta forma, podemos afirmar que o presente trabalho, além de fornecer ferramentas matemáticas baseadas em Análise discriminante (DA) com o objetivo de controlar a qualidade do café em diferentes aspectos, também inova na consideração de múltiplos fatores de qualidade.
The quality of the coffee is dependent on several factors, among them species / cultivars, geographical origin, types of beans, harvesting, post-harvest processing, roasting and storage. In the present work the complexity of the relationship between the quality and aroma composition of the coffee was revealed. Many aspects remain to be fully elucidated, including geographic origin and post-harvest processing, while others may be better understood, such as species influence, grain quality, and storage conditions. In the present study, some aspects such as geographic origin, grain types and roasting were evaluated and correlated through the volatile composition using multivariate analysis tools. In all cases, the volatile composition of the coffee bean was analyzed using the Headspace-SPME technique. The correlation between volatile compounds and the mentioned factors was verified, allowing the elaboration of discriminant models for the differentiation between samples of different geographic origins, degree of roasting and quality seals (beans types). Volatile compounds were identified from geographic origin (macro-regions and micro-regions), degree of roasting and grain quality. Among the volatile markers suggested in the study, 2-methylbutanal is the most versatile marker found, because it is considered important in all geographical discrimination tests, compounds such as 2-ethylpyrazine and 2,5-dimethylpyrazine are important markers for both geographical origin and degree of roasting. From the sensory point of view, the two compounds are linked to sensory notes of peanut and toasted hazelnut. The proposed models were validated through cross validation and permutation tests. The proposed models are of great importance for the quality control and traceability of roasted coffee as non - subjective alternatives for quality control of coffee samples. A literature review was also carried out using the supercritical extraction technique applied in several stages of coffee processing. The optimization of the experimental parameters of SFE was also performed, and the best conditions to maximize the extraction of aromatic oils were 180 bar / 80 ° C / 0% ethanol, which led to rich aromatic profiles of a range of chemical classes, namely aldehydes, phenols, ketones and diketones, pyridines, pyrazines, carboxylic acids, cyclopentenes, furans, pyrroles, alcohols and esters. Consequently, specific process parameters found in this study (temperature of 80 ° C and pressure of 180 bar) can then be applied for industrial scale production for the production of coffee extracts rich in aromatic compounds. In this way, we can say that the present work, besides providing mathematical tools based on discriminant analisys (DA) with the objective of controlling the quality of coffee in different aspects, also innovates in the consideration of multiple factors of quality.
The quality of the coffee is dependent on several factors, among them species / cultivars, geographical origin, types of beans, harvesting, post-harvest processing, roasting and storage. In the present work the complexity of the relationship between the quality and aroma composition of the coffee was revealed. Many aspects remain to be fully elucidated, including geographic origin and post-harvest processing, while others may be better understood, such as species influence, grain quality, and storage conditions. In the present study, some aspects such as geographic origin, grain types and roasting were evaluated and correlated through the volatile composition using multivariate analysis tools. In all cases, the volatile composition of the coffee bean was analyzed using the Headspace-SPME technique. The correlation between volatile compounds and the mentioned factors was verified, allowing the elaboration of discriminant models for the differentiation between samples of different geographic origins, degree of roasting and quality seals (beans types). Volatile compounds were identified from geographic origin (macro-regions and micro-regions), degree of roasting and grain quality. Among the volatile markers suggested in the study, 2-methylbutanal is the most versatile marker found, because it is considered important in all geographical discrimination tests, compounds such as 2-ethylpyrazine and 2,5-dimethylpyrazine are important markers for both geographical origin and degree of roasting. From the sensory point of view, the two compounds are linked to sensory notes of peanut and toasted hazelnut. The proposed models were validated through cross validation and permutation tests. The proposed models are of great importance for the quality control and traceability of roasted coffee as non - subjective alternatives for quality control of coffee samples. A literature review was also carried out using the supercritical extraction technique applied in several stages of coffee processing. The optimization of the experimental parameters of SFE was also performed, and the best conditions to maximize the extraction of aromatic oils were 180 bar / 80 ° C / 0% ethanol, which led to rich aromatic profiles of a range of chemical classes, namely aldehydes, phenols, ketones and diketones, pyridines, pyrazines, carboxylic acids, cyclopentenes, furans, pyrroles, alcohols and esters. Consequently, specific process parameters found in this study (temperature of 80 ° C and pressure of 180 bar) can then be applied for industrial scale production for the production of coffee extracts rich in aromatic compounds. In this way, we can say that the present work, besides providing mathematical tools based on discriminant analisys (DA) with the objective of controlling the quality of coffee in different aspects, also innovates in the consideration of multiple factors of quality.
Descrição
Palavras-chave
Café - Cultivo, Aroma, Café - Torrefação, Controle de qualidade, Geografia regional