Evaluation of cocoa beans profiles and derivatives obtained by HS-SPME and comprehensive two-dimensional gas chromatography using chemometric tools

Orientador: Fabio AugustoTese (doutorado) - Universidade Estadual de Campinas, Instituto de QuímicaResumo: O chocolate é um dos alimentos que mais agradam os consumidores do mundo e seu sabor reside principalmente na fração volátil. O chocolate é produzido utilizando-se as sementes do cacau e para produção do chocolate, as mesmas passam por diversas etapas para desenvolver os compostos responsáveis pelo aroma do chocolate. No desenvolvimento deste trabalho, amostras de sementes de cacau e seus derivados foram estudados utilizando-se como técnica de extração a microextração em fase sólida através do headspace (HS- SPME) e os compostos voláteis foram analisados por GC×GC. Primeiramente foi realizada a otimização das condições de extração utilizando-se um planejamento experimental, além da otimização das condições de separação em GC×GC. Com as condições já otimizadas, quatro diferentes estudos foram conduzidos. No primeiro deles avaliou-se os perfis cromatográficos por meio da MPCA (análise de componentes principais multi-modo) de chocolates de mesmas variedades, produzidos com cacau de duas safras diferentes. Na segunda etapa, os perfis de amostras de cacau em três diferentes estágios foram estudadas: nibs fermentadas, liquor e chocolate . A avaliação das diferenças na composição de acordo com a etapa de produção foram avaliadas por PCA (análise de componentes principais) em função da área dos compostos identificados. A terceira etapa consistiu na avaliação de perfis de nibs fermentadas e não torradas de origens geográficas diferentes, advindas de três estados brasileiros (Pará, Bahia e Rondônia) e da Costa do Marfim, avaliando-se as diferenças de acordo com a região de origem utilizando-se razão de Fisher e PCA. Na última etapa, os perfis cromatográficos de amostras de chocolate amargo comerciais foram estudados, juntamente com o desenvolvimento da análise sensorial destas amostras, onde o PLS (regressão por mínimos quadrados parciais) foi utilizado para correlacionar os perfis com as respostas sensoriais. Desta forma, um estudo dos perfis cromatográficos completos foi desenvolvido para diversas abordagens utilizando-se ferramentas quimiométricasAbstract: Chocolate is one of the foods that please consumers in the world and its flavor are mainly in the volatile fraction. The chocolate is produced by using cocoa beans and in chocolate production, they pass through several steps to develop compounds responsible by chocolate aroma. In this work, cocoa beans samples and its derivatives were studied using as extraction technique the solid phase microextraction through the headspace (HS-SPME) and volatile compounds were analyzed by GC×GC. Optimization of the extraction conditions using an experimental design was carried out, to optimizing separation conditions in GC×GC. With optimized conditions, four different studies were conducted. In the first, the chromatographic fingerprints of chocolates belonging to the same variety obtained in two different harvest were evalueted and the differences were assessed by MPCA (Multi-mode principal component analysis). In the second stage, cocoa samples profiles in three different stages of manufacturing were studied: fermented nibs, liquor and chocolate and the differences in the composition according to the production stage were evaluated by PCA (principal component analysis), using the areas of identified compounds. The third step was the study of fermented and unroasted nibs profiles of different geographical origins, arising from three Brazilian states (Pará, Bahia and Rondônia) and the Ivory Coast, where the evaluation of differences according to region of origin were realized using Fisher ratio and PCA. In the last step, the chromatographic profiles of commercial dark chocolate samples were studied, along with the development of sensory analysis in these samples. PLS (partial least squares regression) was used to correlate the GC×GC profiles with sensory profiles responses. Thus a complete study of the chromatographic profiles was developed using various approaches using chemometric toolsDoutoradoQuimica AnaliticaDoutora em Ciências142221/2012-0CNP

Off-flavors determination in pork meat and fat by GCxGC combined with SPME

Orientador: Fabio AugustoDissertação ( mestrado) - Universidade Estadual de Campinas, Instituto de QuímicaResumo: A carne de porco é a proteina mais consumida no mundo. Para ser consumida a carne necessita de um padrão de qualidade e um dos problemas que afeta esta qualidade é o surgimento de odores desagradáveis. Estes odores, conhecidos como boar taint, são causados principalmente pela presença de androstenona e escatol em níveis maiores que 1,00 mg g e 0,25 mg g, respectivamente, em gordura suína. Os métodos existentes para determinação destes compostos são dispendiosos e não geram resultados em tempos satisfatórios para análise de rotina. Neste trabalho foi proposto um novo método para determinação de androstenona e escatol em gordura suína que se baseia na utilização de microextração em fase sólida (SPME) e cromatografia gasosa bidimensional abrangente (GC xGC). Para isso foi realizada uma otimização univariada do tipo de fibra e agente saponificante e posteriormente uma otimização multivariada, envolvendo concentração de saponificante, tempo de saponificação, temperatura e tempo de extração. O método otimizado foi validado sob os parâmetros de limites de detecção e quantificação, linearidade, precisão e exatidão. Para o escatol é possível a quantificação de amostras com quantidades menores que as detectadas sensorialmente (0,25 mg g), com precisão e exatidão, mas para a androstenona, é possível apenas detectar a presença ou não deste analito. Após todo o desenvolvimento e validação do método, este foi aplicado em sete amostras de toucinho cedidas pelo ITALAbstract: Pork is the must consumed protein the world. For consumpted, the meat needs a quality standard and one of the problems concerning the quality of pork meat are off-flavours. These off-flavores, called boar taint are caused by the presence of two compounds, skatole and androstenone, in levels superior to 1.00 and 0.25 mg g, respectively in pig fat. In order to determine these flavors is necessary to know the concentrations of androstenone and skatole in pig fat. There are specific methods to analyse these compounds, but they spend a lot of time and require a great number of clean-up steps process. In this work, a faster and cleaner method was proposed to determine the presence of androstenone and skatole in pig fat, based in the solid phase microextraction (SPME) and comprehensive bidimensional gas chromatography (GC xGC). A univariate optimization considering the kind of fibre coating and hydrolysis agent was performed. Later a multivariate optimization was developed to determine the concentration of hydrolysis agent, time of saponification and temperature and time of extraction. The best conditions found for the method were used for its validation. The quantification and detection limits, linearity, accuracy and precision were determined. For skatole it is possible to quantify samples at smaller quantities than those found sensorially (0.25 mg g), with precision and accuracy, but for androstenone the method only detects its presence or absence in the analyte. After all the development and validation of the method, it was implemented with seven samples of pig fat, courtesy of ITAL (Instituto de Tecnologia de Alimentos)MestradoQuimica AnaliticaMestra em Químic

Harvest influence in volatile composition of chocolates produced with hybrid varieties of Bahia's cocoa was investigated using GC GC-QMS and chemometrics

Cocoa varieties are important in Brazil due to their resistance to "witch's broom" disease. In this work, the chromatographic profiles of chocolates produced from eleven cocoa varieties harvested from two different harvests were analyzed. A total of 22 samples were analyzed by comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GCxGC-MS), using headspace solid phase microextration (HS-SPME). Multiway principal component analysis (MPCA) were conducted to study the differences between the two harvests. Two principal components were responsible for the separation of the profiles between the harvests and their respective loadings were evaluated. Hydrocarbons were the principal group responsible for this separation. as some pyrazines and aldehydes.624162

Solid-phase Microextraction Combined With Comprehensive Two-dimensional Gas Chromatography For Fatty Acid Profiling Of Cell Wall Phospholipids.

The combination of solid-phase microextraction (SPME) with comprehensive two-dimensional gas chromatography is evaluated here for fatty acid (FA) profiling of the glycerophospholipid fraction from human buccal mucosal cells. A base-catalyzed derivatization reaction selective for polar lipids such as glycerophospholipid was adopted. SPME is compared to a miniaturized liquid-liquid extraction procedure for the isolation of FA methyl esters produced in the derivatization step. The limits of detection and limits of quantitation were calculated for each sample preparation method. Because of its lower values of limits of detection and quantitation, SPME was adopted. The extracted analytes were separated, detected, and quantified by comprehensive two-dimensional gas chromatography with flame ionization detection (FID). The combination of SPME and comprehensive two-dimensional gas chromatography with FID, using a selective derivatization reaction in the preliminary steps, proved to be a simple and fast procedure for FA profiling, and was successfully applied to the analysis of adult human buccal mucosal cells.352438-4

Solid-phase microextraction combined with comprehensive two-dimensional gas chromatography for fatty acid profiling of cell wall phospholipids

The combination of solid-phase microextraction (SPME) with comprehensive two-dimensional gas chromatography is evaluated here for fatty acid (FA) profiling of the glycerophospholipid fraction from human buccal mucosal cells. A base-catalyzed derivatization reaction selective for polar lipids such as glycerophospholipid was adopted. SPME is compared to a miniaturized liquidliquid extraction procedure for the isolation of FA methyl esters produced in the derivatization step. The limits of detection and limits of quantitation were calculated for each sample preparation method. Because of its lower values of limits of detection and quantitation, SPME was adopted. The extracted analytes were separated, detected, and quantified by comprehensive two-dimensional gas chromatography with flame ionization detection (FID). The combination of SPME and comprehensive two-dimensional gas chromatography with FID, using a selective derivatization reaction in the preliminary steps, proved to be a simple and fast procedure for FA profiling, and was successfully applied to the analysis of adult human buccal mucosal cells.351824382444Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade de São Paulo (USP

Solid-phase microextraction combined with comprehensive two-dimensional gas chromatography for fatty acid profiling of cell wall phospholipids

The combination of solid-phase microextraction (SPME) with comprehensive two-dimensional gas chromatography is evaluated here for fatty acid (FA) profiling of the glycerophospholipid fraction from human buccal mucosal cells. A base-catalyzed derivatization reaction selective for polar lipids such as glycerophospholipid was adopted. SPME is compared to a miniaturized liquidliquid extraction procedure for the isolation of FA methyl esters produced in the derivatization step. The limits of detection and limits of quantitation were calculated for each sample preparation method. Because of its lower values of limits of detection and quantitation, SPME was adopted. The extracted analytes were separated, detected, and quantified by comprehensive two-dimensional gas chromatography with flame ionization detection (FID). The combination of SPME and comprehensive two-dimensional gas chromatography with FID, using a selective derivatization reaction in the preliminary steps, proved to be a simple and fast procedure for FA profiling, and was successfully applied to the analysis of adult human buccal mucosal cells.CAPES (Brazilian Ministry of Education Agency for Improvement of Graduate Personnel)CAPES (Brazilian Ministry of Education Agency for Improvement of Graduate Personnel)FAPESP (Foundation for Research of the State of Sao Paulo)FAPESP (Foundation for Research of the State of Sao Paulo)ProReitoria of the University of Sao PauloProReitoria of the University of Sao Paul

Solid‐phase microextraction combined with comprehensive two‐dimensional gas chromatography for fatty acid profiling of cell wall phospholipids

The combination of solid‐phase microextraction (SPME) with comprehensive two‐dimensional gas chromatography is evaluated here for fatty acid (FA) profiling of the glycerophospholipid fraction from human buccal mucosal cells. A base‐catalyzed derivatization reaction selective for polar lipids such as glycerophospholipid was adopted. SPME is compared to a miniaturized liquid–liquid extraction procedure for the isolation of FA methyl esters produced in the derivatization step. The limits of detection and limits of quantitation were calculated for each sample preparation method. Because of its lower values of limits of detection and quantitation, SPME was adopted. The extracted analytes were separated, detected, and quantified by comprehensive two‐dimensional gas chromatography with flame ionization detection (FID). The combination of SPME and comprehensive two‐dimensional gas chromatography with FID, using a selective derivatization reaction in the preliminary steps, proved to be a simple and fast procedure for FA profiling, and was successfully applied to the analysis of adult human buccal mucosal cells351824382444COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPSem informaçãoSem informaçã