Vany Ferraz

A preliminary study on the feasibility of using the composition of coffee roasting exhaust gas for the determination of the degree of roast

Variations in the chemical composition profile of the gas evolved during roasting of coffee were qualitatively monitored with the aim of further establishing a chemical criterion for determination of the degree of roast. Simultaneously, the variations in the beans physical properties, such as volume, weight loss, and moisture content, were also monitored. Three hundred grams of coffee were roasted in a lab-scale roaster and the optimum degree of roast was reached in 9 min. The gas evolved during roasting was collected for gas chromatographic analysis. The chromatograms representing the evolution of the gas composition profile showed that a group of compounds will first appear close to the optimum degree of roast time. This indicated the feasibility of using such compounds as chemical descriptors when establishing a scientific criterion for determination of the degree of roast.

Analysis of free fatty acids and fatty acid phenacyl esters in vegetable oils and margarine by capillary electrochromatography

Capillary electrochromatography (CEC) has been utilized to analyze free fatty acids (FFAs) and fatty acid phenacyl esters (FAPEs) originating from vegetable oils and margarine. The analyses were performed on capillaries 25 and 40 cm long, 100 μm ID, and packed with 3 μm Hypersil ODS. Isocratic elution was achieved with the mobile phase acetonitrile/50 mM 2‐(N‐morpholino)ethane sulfonic acid (MES), pH 6, at a ratio of 9:1. For quantitative analysis, the formation of FAPE derivatives is preferred. Moreover, the number of double bonds in the FAPEs can be elucidated by measuring the UV absorbance ratio of 240:210 nm. For the determination of the oleate/elaidate ratio in margarines, the FFAs are analyzed because of overlap of elaidate/palmitate in FAPE analysis. Data obtained with CEC and micro liquid chromatography (LC) were compared and CEC was found to be far superior in terms of efficiency and speed of analysis. Important selectivity differences were noted between micro LC on highly endcapped ODS and CEC on the silanol‐rich Hypersil ODS.

Improved high-performance liquid chromatographic method for GABA and glutamate determination in regions of the rodent brain

A C18 reversed-phase column and isocratic fluorescence HPLC method for the simultaneous detection of glutamate and gamma-aminobutyric acid (GABA) is described. In this article a fast and more efficient method for the extraction of these neurotransmitters in rat brain tissue is also presented. The supernatant was derivatized with o-phthalaldehyde (OPA) and analyzed by HPLC with fluorescence detection. Intraday reproducibility was 97.0% and 96.7% and interday reproducibility was 97.1% and 93.7% for GABA and glutamate, respectively. Recovery assays indicate that the accuracy of the method for GABA is 99.6+/-2.3% and for glutamate is 101.9+/-1.8%. In addition, the time consumed to run a sample is lower than that described by other authors. Mean elution time was 3.10 min and 8.22 min for glutamate and GABA, respectively. Thus, in a total runtime of less than 9 min both neurotransmitters were detected. Moreover, when compared to the current methods, the extraction solution used here allowed a high drawing out of the neurotransmitters, glutamate and GABA, from the hippocampus, thalamus and prefrontal cortex of the rat brain.

Thiamine deficiency decreases glutamate uptake in the prefrontal cortex and impairs spatial memory performance in a water maze test.

Using an animal model of Wernicke-Korsakoff syndrome, in which rats were submitted to a chronic ethanol treatment with or without a thiamine deficiency episode, the glutamate uptake in the prefrontal cortex and spatial memory aspects were studied. It was found that (i) thiamine deficiency, but not chronic ethanol consumption, induced a significant decrease of glutamate uptake; (ii) thiamine-deficient subjects showed an impaired performance in the water maze spatial memory test though these animals were able to learn the task during the acquisition. In spite of the fact that thiamine deficiency affects both glutamate uptake and spatial reference memory, there was no significant correlation between these two data. The present results show that, although prefrontal cortex is considered by some authors a not vulnerable area to lesions caused by thiamine deficiency, this vitamin deficiency does cause a neurochemistry dysfunction in that region.

FTIR Analysis for Quantification of Fatty Acid Methyl Esters in Biodiesel Produced by Microwave-Assisted Transesterification

Biodiesel was produced by microwave-assisted transesterification of soybean oil with methanol as esterifying agent and sodium methoxide as catalyst. Fourier transform infrared spectroscopy was employed as a fast and reliable analytical technique for the quantification of fatty acid methyl ester content in the produced biodiesel. The quantification was done with the use of a partial least squares model developed based on the infrared spectra obtained. It was shown that microwave irradiation is capable of reducing the reaction time when compared to conventional mechanically stirred reactors used for biodiesel production. In addition, quantification of fatty acid methyl ester content in biodiesel by Fourier transform infrared spectroscopy coupled to multivariate statistics was demonstrated feasible.

Metabolism of benzonitrile by Cryptococcus sp. UFMG‐Y28

The yeast Cryptococcus sp. UFMG‐Y28 can utilize benzonitrile as a nitrogen and possible additional carbon source. The kinetics of growth on Yeast Carbon Base (YCB) added of benzonitrile as sole nitrogen source showed that benzonitrile was metabolized to benzoic acid and ammonia. Liquid chromatography analysis indicated that Cryptococccus sp. UFMG‐Y28 metabolized 12 mM benzonitrile to 10 mM benzoic acid. Resting cells cultivated on YCB‐propionitrile medium showed nitrilase activity against benzonitrile. This strain appears to be promising for bioconversion of nitriles to high value acids and for bioremediation of sites contaminated with aliphatic and aromatic nitriles.

Chemical characterization and antiherpes activity of sulfated polysaccharides from Lithothamnion muelleri

We report herein the chemical characterization and antiherpes activity of polysaccharides from the red alga Lithothamnion muelleri (Hapalidiaceae). The polysaccharide-rich fractions B1 and B2 were obtained by extraction with Na2CO3 and were purified by size exclusion chromatography to afford Fra-B1 and Fra-B2. The polysaccharides were characterized by FT-IR and chemical analysis (total contents of carbohydrates, proteins, sulfate and uronic acid), whereas their average molecular weights were estimated by high performance gel permeation chromatography. The monosaccharide analysis detected galactose, glucose, xylose, mannose, rhamnose and arabinose in the four polysaccharide samples. Antiherpetic in vitro assays showed that B1 and B2 inhibited Herpes Simplex Virus types 1 and 2 (HSV-1 and HSV-2) when added simultaneously to viral infection affording selectivity indices (SI=CC50/EC50) higher than 20. Investigation of the mechanism of action indicated that B1 and B2 act on the initial steps of HSV replication, mainly inhibiting viral adsorption but also viral penetration into the cells.

Double use of microwaves in fatty acid preparation for elaidic acid determination as phenacyl ester using high-performance liquid chromatography in Brazilian fat products.

Brazilian samples of fat products like margarines, butters and chocolates were prepared to reversed-phase high-performance liquid chromatography analysis, using a domestic microwave oven for fat hydrolysis and derivatization with phenacyl chloride. The total reaction time was 6 min, recoveries were above 94%. Total reproducibility for whole procedure were 3.5% R.S.D. for elaidic acid (n=3), the total chromatography analysis was 25 min.

Avaliação do potencial de cinco cultivares de videiras americanas para sucos de uva no sul de Minas Gerais

Objetivou-se, no presente trabalho realizar uma caracterizacao dos sucos de uva de cinco cultivares de videira americana Vitis labrusca (Folha de Figo, Alwood, Concord, BRS-Rubea e Isabel) segundo suas caracteristicas visuais, olfativas e gustativas, utilizando um metodo descritivo por um painel de degustadores da Embrapa Uva e Vinho (EMBRAPA/CNPUV) de Bento Goncalves e da Associacao Brasileira de Enologia (ABE), constituido por doze degustadores. De acordo com os resultados, os sucos das cultivares Isabel e Folha de Figo foram superiores aos demais, segundo a analise de componentes principais (ACP), principalmente pelas variaveis limpidez, equilibrio olfativo, intensidade e corpo gustativo, persistencia olfato-gustativa e julgamento geral (notas). O suco Folha de Figo foi superior ao Isabel quanto a tonalidade, sendo o primeiro caracterizado como vermelho-violaceo. A cultivar Folha de Figo e a mais utilizada na regiao para a producao de suco, podendo os produtores utilizarem tambem a cultivar Isabel, que mostrou potencial nas condicoes edafo-climaticas do sul de Minas Gerais.

Analysis of fatty acids released by crotoxin in rat brain synaptosomes

Crotoxin, the main toxin of Crotalus durissus terrificus venom, exerts its lethal effect by blocking neurotransmission at the neuromuscular junction level through a triphasic mechanism. This effect seems to depend on its phospholipasic activity, suggesting that the mechanism of neurotransmission blockage may be related to fatty acids release in specific sites of the nervous terminal. In this work, we purified the fatty acids released by crotoxins activity and this outline was compared with other phospholipases A(2), including CB, a subunit of crotoxin. Our results show a higher release of palmitate and arachidonate by crotoxin when compared to other phospholipases A(2). Since palmitate has a role in protein acylation processes and arachidonate participates in signal transduction events, these mechanisms may be related to the neurotoxic actions of crotoxin.