Journal of the Brazilian Chemical Society
URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/13322
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Item Green and roasted arabica coffees differentiated by ripeness, process and cup quality via electrospray ionization mass spectrometry fingerprinting(Sociedade Brasileira de Química, 2009) Amorim, Ana Carolina L.; Hovell, Ana Maria C.; Pinto, Angelo C.; Eberlin, Marcos N.; Arruda, Neusa P.; Pereira, Elenilda J.; Bizzo, Humberto R.; Catharino, Rodrigo R.; Morais Filho, Zenildo B.; Rezende, Claudia M.Direct infusion electrospray ionization mass spectrometry in both the negative ESI(-)-MS and positive ESI(+)-MS ion modes are investigated to differentiate green and roasted Arabica coffees with different stages of ripeness (green, ripe and overripe), post-harvesting process (dry, wet and semi-wet) and coffees with diferente cup qualities. In the ESI(-)-MS of green coffees, ions from deprotonated fatty acids and chlorogenic acids are the most important for ripeness discrimination. In the ESI(+)-MS, maturity is differentiated by ions from protonated caffeine, chlorogenic acids and K+ adducts of fatty acids. To differentiate between post-harvesting process in both ionization modes, ions from fatty acids, chlorogenic acids, sugars and carboxylic acids generated in the fermentation process are the most representative. Roasted Arabica coffees are also well discriminated: in the ESI(-)-MS, ions from chlorogenic acids and short-chain organic acids derived from sugars are important. In the ESI(+)-MS, discrimination are mainly performed by low m/z ions such as protonated pyridine and alkylpiridines formed via trigonelline degradation. Both ESI(+)-MS and ESI(-)-MS are able to differentiate cup quality for Arabica roasted coffees and the ions used to perform discrimination are the same ones described in ripeness and post-harvesting processes.Item Age and time related pheromone production in coffee leafminer Leucoptera coffeella Guérin-Méneville (Lepidoptera: Lyonetiidae)(Sociedade Brasileira de Química, 2008) Lima, Eraldo R.; Vilea, Evaldo F.; Lucia, Terezinha M. C. Della; Ataíde, Lívia M. S.This study was undertaken to access the pattern of sex pheromone production in glands of virgin females of Leucoptera coffeella as an indirect measure of the calling behavior. The major compound, 5,9-dimethylpentadecane (1) was extracted from pheromone glands of virgin females to be used in two experiments. The first one investigated the effect of the pheromone production time by females (extracts of 10 females with age of two days were carried out at 2-hour intervals). The other experiment evaluated the effect of female age on pheromone production (10 females with age ranged from 1 to 5 days after emergence class were used). Hexane extracts were made with 5 ng µL-1 of 5,9-dimethylheptadecane (2) as internal standard and analyzed by GC. Females had the highest amount of pheromone at the last four hours in the dark and the two first hours in the light period. One-day old females produced the highest amount of pheromone in the glands.Item The use of fatty acid profile as a potential marker for brazilian coffee (Coffea arabica L.) for corn adulteration(Sociedade Brasileira de Química, 2008) Jham, Gulab N.; Berhow, Mark A.; Manthey, Linda K.; Palmquist, Deborah A.; Vaughn, Steven F.Fatty acid methyl ester (FAME) composition of the coffee (Coffea arabica L.) varieties Catuai, Catucaí, Bourbom, Mundo Novo, Rubí and Topázio known to produce beverage of intermediate, excellent, excellent, intermediate, intermediate and poor quality, respectively, was determined for the first time. Average area % of the FAMEs of the six varieties was: palmitic (38.2), stearic (8.3), oleic (8.6), linoleic (38.5), linolenic (1.6) and arachidic (3.6) acids, respectively. The method was very quick with complete characterization (>99%) of the samples studied being possible in less than 6 min. While these values may provide insights for evaluating the coffee quality, no significant effect (p < 0.05) of coffee variety was found on area % of the FAMEs. In addition, FAMEs of six corn samples, six commercial coffee brands and one commercial coffee sample intentionally contaminated with three levels of corn were compared. Although the linoleic/stearic ratio was significantly different in coffee and corn FAMEs, this probe could not be used a marker to detect corn adulteration in commercial coffees.Item Comparative studies of the sample decomposition of green and roasted coffee for determination of nutrients and data exploratory analysis(Sociedade Brasileira de Química, 2007) Amorim Filho, Volnei R.; Politoa, Wagner L.; Gomes Neto, José A.The contents of some nutrients in 35 Brazilian green and roasted coffee samples were determined by flame atomic absorption spectrometry (Ca, Mg, Fe, Cu, Mn, and Zn), flame atomic emission photometry (Na and K) and Kjeldahl (N) after preparing the samples by wet digestion procedures using i) a digester heating block and ii) a conventional microwave oven system with pressure and temperature control. The accuracy of the procedures was checked using three standard reference materials (National Institute of Standards and Technology, SRM 1573a Tomato Leaves, SRM 1547 Peach Leaves, SRM 1570a Trace Elements in Spinach). Analysis of data after application of t-test showed that results obtained by microwave-assisted digestion were more accurate than those obtained by block digester at 95% confidence level. Additionally to better accuracy, Other favorable characteristics found were lower analytical blanks, lower reagent consumption, and shorter digestion time. Exploratory analysis of results using Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) showed that Na, K, Ca, Cu, Mg, and Fe were the principal elements to discriminate between green and roasted coffee samples.Item Sistematic study of benzo[a]pyrene in coffee samples(Sociedade Brasileira de Química, 2006) Badolato, Elza S. G.; Martins, Maristela S.; Aued-Pimentel, Sabria; Alaburda, Janete; Kumagai, Edna E.; Baptista, Gisleine G.; Rosenthal, AmauryA method for extracting and quantifying benzo[a]pyrene (B[a]P) was evaluated and improved for samples of green and roasted ground Arabica (Coffea arabica) and Conillon (Coffea canephora) Brazilian coffees. The influence of the roasting process in B[a]P formation was considered too. These samples were extracted with acetone, followed by saponification and cyclohexane extraction. The extracts were cleaned by chromatography on a silica-gel. The quantification was done by HPLC with reversed-phase and fluorescence detection under isocratic conditions. The detection and quantification limits were 0.03 μg kg-1 and 0.10 μg kg-1, respectively. The recovery ranged from 76 to 116% for concentrations between 1.00 and 3.00 μg kg-1. The values obtained for B[a]P concentrations were from 0.47 to 12.5 μg kg-1 for samples of ground roasted coffee. B[a]P was absent in the green coffee samples. The control of the roasting parameters is fundamental for obtaining a good quality product.Item A solid-phase microextraction method for the chromatographic determination of organophosphorus pesticides in fish, water, potatoes, guava and coffee(Sociedade Brasileira de Química, 2005) Capobiango, Helena L. V.; Cardeal, Zenilda L.This paper describes a Solid Phase Microextraction method (SPME-CG) to the determination of organophosphorus pesticides in samples of fresh-water fish, water, potatoes, guava and coffee by capillary gas chromatography with nitrogen phosphorus detector. The samples were collected from October 2002 to April 2003 in the tributaries and sub-tributaries of the Paranaiba River, which supplies the city of Patos de Minas, Minas Gerais, Brazil. The determination of the pesticides: co-ral (O,O-diethyl O-(3-chloro-4-methyl-2-oxo-2H-1-benzopyran-7-yl) phosphorothioate), DDVP (2,2-dichloroethenyl dimethylphosphate), disyston (O,O-diethyl S-[2-(ethylthio) ethyl] phosphorodithioate), ethion (O,O,O’,O’-tetraethyl S,S’-methylene bis(phosphorodithioate)), phorate (O,O-diethyl S-ethylthiomethyl phosphorodithioate), phosdrin (2-methoxycarbonyl-1-methylvinyl dimethyl phosphate), guthion (O,Odimethyl-S-[(4-oxo-1,2,3-benzotriazin-3(4H)-yl)methyl] phosphorodithioate)), malathion (diethyl (dimethoxy thiophosphorylthio succinate) and methyl-parathion (O,O-dimethyl O-4-nitrophenyl phosphorothioate) in samples of fish, water and others foods with a manual SPME-CG holder using a 100 μm PDMS microfiber, is simple, easy to handle and solvent-free. The optimised conditions for pesticides extraction by SPME-CG method were: sample agitation, absorption at room temperature for 40 min, desorption at 220°C for 10 min, and sample volume in the vial of 16.0 mL. Under these conditions, the analytical curves were linear in different ranges (depend of each pesticide) with correlation coefficients from 0.997 to 0.999 and the precision was good (RSD from 4.40 to 15.13%). The detection limit was 0.05 μg L-1 to 8.37 μg L-1 and the quantitation limit was 0.09 μg L-1 to 8.70 μg L-1. The method was employed to detect and quantify pesticides in 24 fish of three different species and also in water, potatoes, guava and coffee. The samples analyzed showed residues of six different organophosphorus pesticides.Item Boron isotope dilution in cellular ractions of coffee leaves evaluated by inductively coupled plasma mass spectrometry with direct injection nebulization (DIN-ICP-MS)(Sociedade Brasileira de Química, 2003) Bellato, Ana Cláudia S.; Menegário, Amauri A.; Giné, Maria FernandaEnriched 10B (94.14 atom %) was supplied to coffee plantlets for three months. Then boron isotope ratios were determined in the leaf cell compartments, cell wall, nuclei and chloroplast, after a sub-cellular fractionation procedure. The isotopic measurements were performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) provided with a direct injection nebulizer (DIN), introducing a sample volume of 50 µL. Isotopic ratios from 1.002 to 1.326 were determined with precision characterized by RSD lower than 1.5% for the enriched cell fractions with B concentrations ranging from 3.3 to 10.8 µg g-1. The detection limit (3σ) was 0.5 ng B mL-1. The average enrichments in 10B atom % found in the cell walls, nuclei and chloroplasts were 46.7, 44.5 and 48.8, respectively.