Química Nova
URI permanente para esta coleção${dspace.url}/handle/123456789/13323
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Item Perfil volátil do Coffea arabica e Coffea canephora var. Conilon por SHS-GC-MS e quimiometria(Sociedade Brasileira de Química, 2023-11-20) Lyrio, Marcos Valério Vieira; Cunha, Pedro Henrique Pereira da; Debona, Danieli Grancieri; Agnoletti, Bárbara Zani; Frinhani, Roberta Quintino; Oliveira, Emanuele Catarina da Silva; Filgueiras, Paulo Roberto; Pereira, Lucas Louzada; Castro, Eustáquio Vinicius Ribeiro deThe volatile composition of coffee exerts a substantial influence on its quality, as it defines the characteristics of the beverage. However, these compounds are influenced by factors within the coffee production chain, such as botanical origin, geography, processing methods, and roasting. Consequently, the identification of such compounds becomes a vital tool for characterizing coffees to these factors. In this context, gas chromatography with headspace extraction is widely used for aroma analysis, providing a composition closer to consumer perception. Headspace extraction offers speed, simplicity, minimal sample preparation, and no need for solvents. In this study, static headspace extraction (SHS) coupled with gas chromatography-mass spectrometry (SHS-GC-MS) was employed to establish the chemical profile of volatile compounds in Coffea arabica and Coffea canephora var. conilon and determine discriminants between the species. A total of 97 compounds, belonging to 17 chemical classes, were identified. The chemometric analysis highlighted furans, phenols, and carboxylic acids as key differentiating classes. Notably, furfuryl alcohol, acetic acid, 4-vinylguaiacol, N-acetyl-4(H)-pyridine, and N-furfurylpyrrole emerged as crucial volatile compounds. The variable selection using Fisher weight applied directly in the chromatograms, produced models consistent with relative area data, with furfuryl alcohol and 4-vinylguaiacol regions being particularly influential in differentiation.Item Infravermelho portátil na região do próximo (NIR) aplicado no controle de qualidade de cafés adulterado por borra(Sociedade Brasileira de Química, 2021-12-02) Correia, Radigya M.; Cunha, Pedro H.; Agnoletti, Bárbara Z.; Pereira, Lucas L.; Partelli, Fábio L.; Filgueiras, Paulo R.; Lacerda Jr, Valdemar; Romão, WandersonThe objective of this work was to control the purity level of canephora coffees (Conilon coffee) from the state of Espírito Santo (Brazil), as a function of the addition of grounds produced by the coffees themselves using a portable microspectrometer in the infrared region. (microNIR), associated with chemometric tools. The PCA model grouped the coffees according to the level of adulterant in the samples and showed that the presence of moisture and polysaccharides is important for the discrimination between pure and adulterated samples. PLS-DA and SIMCA classification models were built with commercial samples and resulted in the discrimination of authentic and non-authentic samples with accuracy values above 90% and 82% for PLS-DA and SIMCA, respectively. The quantification results presented by the PLS model were satisfactory for all models, reaching the best results at 75 °C with RMSEP values of 6.13 wt%, R2p = 0.9917; and LOD in the range of 5.6-8.9 wt%; LOQ = 17-26.8 wt%, according to IUPAC; relative standard deviation for repeatability of 1.0 and 1.7 wt%; and intermediate precision of 3.4 and 1.1 wt% for low (<10 wt%) and high (≈ 90 wt%) levels of adulterants, respectively. Therefore, this work represents the first exploratory study to analyze adulterations with coffee grounds by portable NIR, demonstrating the potential of the equipment against this type of adulteration.