Processamento de frutos de abacaxizeiro cv smooth cayenne: perfil de açúcares e ácidos dos sucos e composição nutricional da farinha de cascas

O desenvolvimento de tecnologias que permitam o aproveitamento integral dos frutos é de grande importância para as indústrias. Uma possibilidade de valorização da cultura do abacaxi seria o estímulo ao processamento do fruto para a obtenção do suco associado ao aproveitamento das cascas para a elaboração de farinha, produto de mercado crescente. Um dos fatores de grande importância para a aceitação do suco é o sabor, que se encontra diretamente relacionado ao perfil de ácidos e açúcares presentes. Nesta linha, este trabalho visou a processar frutos de abacaxi cv Smooth Cayenne colhidos em dois estádios de maturação para a obtenção e a caracterização do suco e da farinha de cascas. Os sucos obtidos foram analisados em HPLC para o perfil de açúcares e ácidos orgânicos. As farinhas de casca foram analisadas para rendimento, umidade, cinzas, fibras solúvel e insolúvel, lipídeos, proteína e carboidratos totais. Os resultados obtidos mostraram que frutos em estádio mais avançado de maturação produzem sucos com maior teor de açúcares e menor teor de ácidos, sendo o principal ácido o cítrico, e os açúcares frutose, glicose e sacarose. As farinhas de abacaxi apresentam-se como fontes de fibras insolúveis.

Determinação de Ácidos Carboxílicos na Atmosfera Urbana de São Paulo: uma abordagem analítica e ambiental

In this work, analytical strategies are evaluated in order to measure accurately the ambient levels of atmospheric organic acids. Environmental considerations about the determination of low molecular weight mono- and di-carboxylic acids from urban areas of São Paulo are described.

Triterpenos esterificados com ácidos graxos e ácidos triterpênicos isolados de Byrosonima microphylla

The hexane extract of leaves of B. microphylla afforded a mixture of triterpenes esterified with fatty acids. Analyses of spectral data of the mixture and of the derivatives obtained by a transesterification reaction with NaOMe/MeOH permitted to identify the composition of the mixtures as being 24-hydroxy-urs-12-enyl 3b-eicosanate, estearate and palmitate as well as of the 24-hydroxy-olean-12-enyl 3b-eicosanate, estearate and palmitate. From the choroform and ethyl acetate extracts were isolated the oleanolic and 3b,24-dihydroxy-urs-12-en-28-oic acids, quercetin and methyl galic ester, respectively. The compounds were identified through analysis of their spectral data.

Caracterização de ácidos húmicos de vermicomposto de esterco bovino compostado durante 3 e 6 meses

The main objective of this research was the characterization of the humic fractions isolated from vermicomposting, originating from cattle manure and treated with Eisenea foetida or Lumbricus rubellus, during 3 and 6 months. Elemental analysis and Infrared and UV-vis spectroscopy were used for their characterizations. The results obtained shown that both humic acids are very similar, but six-month humic acid shown lower percentage of organic material than three month humic acid. The spectroscopy analysis shown that the humic acid studied can be compared with other humic acids reported in the literature. By comparing both vermicomposts, the one produced in three months presents a great potential as fertilizer and it is more economical than the vermicompost produced during a six month period.

Desenvolvimento de um sistema de filtração e titulação para determinação da acidez de ácidos húmicos

The acidity determinations method of humic acids (HA) content was developed by Schnitzer and Gupta and is a very well known procedure. Nevertheless, care is necessary to prevent measure errors due to non-controlled BaCO3 production, during the filtration and titration of HA total acidity. To overcome this problem, we developed in our laboratory a simple filtration and titration system for the determination of HA acidity under inert atmosphere. This system enables a better reproducibility and accuracy of total, carboxylic and phenolic acidity measures than those by Schnitzer and Gupta method.

Ligações hidrogênio fortes em ácidos dicarboxílicos e diaminas aromáticas

A very short-strong hydrogen bond (<2 Å, >20kcal/mol) is found in the monoanion of certain dicarboxylic acids derived from maleic and dialkylmalonic acids. Certain aromatic diamines that are known as proton sponge have exceptionally high basicity (pKa) and are only monoprotonated with strong acids like percloric acid. The closed proximity between the two basic centers provokes a strong steric interaction that is relieved upon protonation. Similar effects are found in dicarboxylic acids (hydrogen maleate and hydrogen dialkylmalonates) that present a very short distance between the two oxygens and a short-strong hydrogen bond.

Origem e implicações dos ácidos carboxílicos na atmosfera

A general overview about the ambient levels of low molecular weight carboxylic acids and their possible emission sources, as well as the implication of them in the atmosphere is presented. Carboxylic acids are considered to be one of the dominant classes of organic compounds found in the atmosphere in a variety of phases, such as in rainwater, snow and ice, on aerosol particles and gas phase. They may be originated from biogenic and anthropogenic direct emissions and by photochemical reaction in situ. Emission sources and formation mechanisms of organic acids in the atmosphere are discussed.

Aumento da resolução de espectros de RMN 13C de ácidos húmicos em solução através do tratamento prévio com KCl 0,03 mol L-1

High levels of Fe and Mn present in some soils and compost organic matter decrease the resolution of 13C NMR spectra of humic substances. Addition of KCl up to a concentration of 0,03 mol L-1 to humic substances extracts followed by centrifugation is an efficient method of eliminating clays and minerals containing high levels of paramagnetic metals such as Fe and Mn thus increasing the resolution of 13C NMR spectra.

Estudo semi-empírico de ácidos hidroxâmicos: ácido formoidroxâmico e derivados do aleloquímico dimboa

Open chain hydroxamic acid (Hx) can exist as Z and E diastereomers of two tautomers, hydroxamic acid and hydroximic acid. The conformational stability of the formohydroxamic acid isomers evaluated by PM3 compared better to ab initio results from the literature than AM1 results. Structural data of the cyclic Hx 2,4-dihydroxy-7-metoxy-2H-1,4-benzoxazin-3(4 H)-one (DIMBOA) obtained by both semiempirical methods compared well to ab initio results. pKa data from the literature for derivatives of the aldolic isomer of DIMBOA were compared to the stability of the anions resulting from the loss of protons of their phenol and hydroxamic acid groups, determined as the difference in heat of formation between anionic and neutral forms, calculated by AM1 and PM3 methods. Good correlations between theoretical and experimental data were obtained for both semiempirical methods.

Tensoatividade de ácidos húmicos de procedências distintas

The surface activity of humic acids (HA) is a parameter which might be considered in the evaluation of all types of aggregation of these substances. In this work the surface tension of aquatic and terrestrial-HA aqueous solutions was observed under varied conditions of pH, concentration and ionic strength. Results showed that HA present surface activity for a extent range of concentration. The surface tension decreases with HA concentration increasing and, for all samples exist a concentration value above which a reduction in the rate of the solute migration to the solution surface is observed. This value is sensibly reduced and sharpened with the increasing of the ionic strength. Surface tension is also reduced with the acidity increasing, being a minimum reached between pH 3 and 5. Observed effects are explained in view of conformational arrangements of HA which tend to agglomerate in micelle-like domains in aqueous solutions.

Efeito da aplicação foliar de ácidos graxos na "Via das Lipoxigenases" de plantas de soja

The involvement of lipoxygenase isozymes in several physiological processes of plants has been described but their role is not well understood and more biochemical studies are needed to elucidate the role of the "Lipoxygenase Pathway" in plant physiology. Thus, the biochemical and kinetic characterization of a lipoxygenases "pool" from soybean leaves was carried out. Two genotypes were used: IAC-100 (a normal variety having lipoxygenases in the seeds) and IAC-100 TN (genetically modified genotype, which is devoid of lipoxygenases in the seeds). The plants were submitted to the application of fatty acids (lipoxygenase substrates) on leaves. The results of the biochemical and kinetic studies of lipoxygenase isozymes from leaves of the two genotypes analysed showed that genetic removal of lipoxygenase from seeds did not affect the response of the plant to the treatment, since both genotypes showed similar results.

Aplicação de lipases microbianas na obtenção de concentrados de ácidos graxos poliinsaturados

Several polyunsaturated fatty acids (PUFA) belonging to the ômega 6 series, such as cis-6,9,12 gamma-linolenic acid, as well as those of the ômega 3 series, such as cis-5,8,11,14,17-eicosapentaenoic acid and cis-4,7,10,13,16,19-docosahexaenoic acid are of considerable interest due to their nutritional and therapeutic properties. Methods used for the concentration of PUFA from natural sources include urea adduct formation, solvent winterization, supercritical fluid extraction and lipase-catalyzed reaction. Lipases are known to have little reactivity on PUFA and these acids can be enriched by selective hydrolysis, direct esterification of glycerol with PUFA and interesterification. Since lipase reactions are advantageous with respect to fatty acid, positional specificities and mild incubation condition, these enzymes are considered to be suitable for the production of PUFA concentrates for medical purposes.

Dimensão fractal de ácidos húmicos em diferentes condições experimentais

The determination of fractal dimension (D) of humic particles was achieved by the turbidimetric technique where diluted suspensions of humic acids, in different experimental conditions, were analyzed by spectrophotometry UV-Vis. The slope of the lines (beta) was taken from the graphics (logtauvs loglambda) to obtain D. The results show that the values of D changed according to pH (3.0, 5.0 and 7.0), temperature (25 and 5 ºC) and shaking (magnetic and horizontal). In general, the value of D decreased with the increment of pH, increase of shaking and decrease of temperature.

Análise de ácidos graxos por eletroforese capilar utilizando detecção condutométrica sem contato

This article describes a novel approach to the separation of fatty acids ranging from 8 to 20 carbons using capillary electrophoresis with contactless conductivity detection. Complete separation of nine linear chain fatty acids (from C8:0 to C20:0) was achieved in 15 min under normal polarity operation. Limits of detection ranged from 35 to 319 µmol L-1 for C20:0 to C8:0, respectively. The optimized running electrolyte composition was 5.0 mmol L-1 phosphate buffer at pH 7, 4.0 mmol L-1 dimethyl-b-cyclodextrin, 2.0 mmol L-1 trimethyl-b-cyclodextrin, acetonitrile 50% (v/v), and methanol 20% (v/v). The applicability of the separation system was demonstrated by the analysis of coconut vegetable oil.

Análise de ácidos graxos não-esterificados de plasma humano por cromatografia gasosa capilar com injeção sem divisão de fluxo

The aim of the present work was to test the combination of non-esterified fatty acid (NEFA) isolation using fumed silicon dioxide with capillary gas-chromatography (C-GC) with splitless injection for the analysis of NEFAs in human plasma. Injection volume, solvent re-condensation and split purge flow-rate were the parameters evaluated for the analysis of fatty acid methyl esters by C-GC. The use of a solvent re-condensation technique, associated with 1.0 µL injection and a split purge flow rate of 80 mL/min resulted in satisfactory analysis of NEFAs. Fourteen fatty acids were identified in plasma samples, ranging from 2.03 to 184.0 µmol/L. The combination of both techniques proved useful for routine analyses of plasma NEFAs.