Determinação de compostos de massa molecular alta em folhas de plantas da Amazônia

The fractIons of dichloromethane extracts of leaves from andiroba (Carapa guianensis - Meliaceae), caapi (Banisteriopsis caapi - Malpighiaceae), cocoa (Theobroma cacao - Sterculiaceae), Brazil nut (Bertholletia excelsa - Lecytidaceae), cupuaçu (Theobroma grandiflorum - Sterculiaceae), marupá (Simaruba amara - Simaroubaceae) and rubber tree (Hevea brasiliensis - Euphorbiaceae), were analyzed by HT-HRGC and HT-HRGC-MS. Esters of homologous series of fatty acids and long chain alcohols, phytol, amyrines and tocopherols were characterized. The characterization of the compounds was based mainly in mass spectra data and in addition by usual spectrometric data (¹H and 13C NMR, IR).

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.

Constituintes químicos de Melaleuca alternifolia (Myrtaceae)

The first chemical study of non-volatile constituents from the bark and stem of Melaleuca alternifolia (Myrtaceae) led to the isolation and identification of 3,3'-O-dimethylellagic acid (1) and five pentacyclic triterpenes: 2alpha,3beta,23-trihydroxyolean-12-en-28-oic acid (arjunolic acid, 2), 3beta-hydroxylup-20(29)-en-27,28-dioic acid (melaleucic acid, 3), betulinic acid (4), betuline (5), 3beta-O-acetylurs-12-en-28-oic acid (6), a mixture of fatty acids and esters, and several hydrocarbons. For 2alpha,3beta,23-trihydroxyolean-12-en-28-oic acid (2) and 3beta-O-acetylurs-12-en-28-oic acid (6) a first detailed assignment of ¹H NMR is presented.

Constituintes químicos das cascas do caule de Cenostigma macrophyllum: ocorrência de colesterol

Phytochemical investigation of the bark of Cenostigma macrophyllum (Leguminosae-Caesapinioideae) resulted in the isolation and identification of valoneic acid dilactone, ellagic acid, lupeol, alkyl ferulate, four free sterols (cholesterol, campesterol, stigmasterol and sitosterol), a mixture of sitosteryl ester derivatives of fatty acids, sitosterol-3-O-beta-D-glucopyranoside, stigmasterol-3-O-beta-D-glucopyranoside and saturated and unsaturated fatty acids. The structures of the isolated compounds were identified by ¹H and 13C NMR spectral analysis and comparison with literature data. The mixtures of 3-beta-hydroxysterols and fatty acids were analysed by GC/MS.

70º aniversário do biodiesel em 2007: evolução histórica e situação atual no brasil

Periodically, during petroleum shortages, vegetable oils and their derivatives have been proposed as alternatives to petroleum diesel fuel. Different approaches have been proposed, including the use of pure vegetable oils (or blends) or their derivatives. Indeed, the use of fatty-acid methyl or ethyl esters (usually known as "biodiesel") produced by alcoholysis of triacylglycerides or esterification of fatty acids was initially proposed in Belgium 70 years ago, when the first world patent was deposited. Recently, foreign dependence on diesel fuel and the petroleum crisis have increased the discussion in Brazil on starting to use alternatives to diesel fuel, being biodiesel the alternative of choice for a large petroleum diesel substitution program.

A convenient method for lecithin purification from fresh eggs

The increasing demand for fatty acid-free lecithin required modifications in existing purification methods. In this technical note we describe a purification procedure with the following steps: a) homogenization and extraction of yolks obtained from fresh eggs with acetone, b) solubilization with ethanol and solvent elimination and c) repeated solubilization/precipitation with petroleum ether/acetone. This crude extract was chromatographed on neutral alumina, which was exhaustively washed with chloroform before elution with chloroform:methanol, allowing the sequential separation of fatty acids and lecithin. Chromatographic behavior and mass spectra of the product are presented. This fast procedure yields fatty acid-free lecithin at a competitive cost.

Perfil de ácidos graxos e avaliação da alteração em óleos de fritura

The present study had the purpose of evaluating the profile of fatty acids and the total alteration of cottonseed, sunflower and palm oils brought about during discontinued frying processes of cassava frozen chips. An increase in the percentage of saturated fatty acids and a decrease in polyunsaturated fatty acids was observed, regardless of the type of oil used. With regard to the oil's global alteration, the results showed that palm oil, the most saturated one, underwent less alteration. However, none of the oils presented total polar compound values above the limits prescribed.

Monoglicerídeos: produção por via enzimática e algumas aplicações

Monoglycerides (MAG) are non-ionic surfactants, widely used in the pharmaceutical, food and cosmetic industries. Although MAGs are manufactured on an industrial scale by chemical glycerolysis of oils and fats, new developments in lipase catalyzed synthesis have been studied as an alternative to the classical method seeking to use clean technology and green chemistry. In this work, different methods such as glycerolysis, selective hydrolysis of fats and oils, and esterification of fatty acids or transesterification of esters with glycerol are presented. The properties and applications of the monoglycerides are also included in this review.

Biocombustíveis a partir de óleos e gorduras: desafios tecnológicos para viabilizá-los

Periodically, during petroleum shortage, fatty acids and their derivatives have been used as alternative fuels to those derived from petroleum. Different approaches have been proposed, including the use of neat fats and oils or their derivatives. Indeed, the utilization of biodiesel produced by alcoholysis of triacilglycerides or esterification of fatty acids, or hydrocarbons obtained from cracking of fatty materials were studied and used in several countries. Increasing concerns about energy security and climate changes have lead several countries, including Brazil, to start up biofuels programs. Different technologies are currently being developed in order to produce biofuels with economical feasibility. In this work are discussed alternative fatty raw-materials and processing technologies that are currently being studied in order to produce fuels suitable to sustainable substitute diesel fuel.

Lipídios estruturados: alternativa para a produção de sucedâneos da gordura do leite humano

Human milk has characteristics of great importance for the newborn. Its composition shows all nutrients in quantity and quality needed, in addition to providing protection against infections and allergies and stimulating the immune system. Therefore, the composition of fatty acids and their distribution in the triacylglycerols are targets of studies on infant formula, and the triacylglycerols of human milk fat should serve as a model for the lipid components. This review aims to report studies of technology in lipids in order to produce structured lipids as substitutes of human milk fat.

Esterificação de ácidos graxos utilizando zircônia sulfatada e compósitos carvão ativado/zircônia sulfatada como catalisadores

In this work sulfated zirconia (SZr) and activated carbon/SZr composites produced by impregnation method with or without heating treatment step (CABC/SZr-I and CABC/SZr-I SC) and by the method of synthesis of SZr on the carbon (CABC/SZr-S) was used as catalysts in the esterification reactions of fatty acids. The SZr presented very active, conversions higher than 90% were obtained after 2 h of reaction. The activity of the composite CABC/SZr-I20%SC was up to 92%, however, this was directly related to time and temperature reactions. CABC/SZr-I and CABC/SZr-S were less active in esterification reactions, what could be attributed to its low acidity

Estudio del coeficiente de reparto de ácidos carboxílicos grasos en sistemas modificados heptano/agua

The use of fatty acids (FAs) as amphiphiles is very important because they have a behaving similar to surfactants. The formulation for the preferential partition of these species was studied by varying the amount of salt at constant acid concentration. As the salt concentration increases, a Winsor I→III→II transition is observed for all the systems studied. Furthermore, the electrolyte concentration required to obtain the optimum formulation varies inversely with the chain length of the acid. The partition coefficient of the surfactant allows one to obtain thermodynamic information on the acid transfer process between the phases of the system.

PRODUÇÃO DE BIODIESEL A PARTIR DE ÁCIDOS GRAXOS PROVENIENTES DO REFINO DE ÓLEOS VEGETAIS VIA CATÁLISE ÁCIDA HETEROGENEA E MICRO-ONDAS

This work presents the biofuel production results of the esterification of fatty acids (C12-C18) and high-acid-content waste vegetable oils from different soap stocks (soybean, palm, and coconut) with methanol, ethanol, and butanol by acid catalysis. We used Amberlyst-35 (A35) sulfonic resin as a heterogeneous acid catalyst and p-toluenesulfonic acid as a homogeneous catalyst for comparison. Both the heterogeneous (A35) and homogeneous (p-toluenesulfonic acid) reactions were performed with 5% w/w of catalyst. The final products were analyzed by proton nuclear magnetic resonance (1H NMR). The homogeneous catalyzed esterification of fatty acids with methanol, ethanol, and butanol produced esters with yields higher than 90%. In the reaction with fatty acids and methanol catalyzed by A35, the best results were achieved with lauric acid and methanol, with a yield of 97%. An increase in the hydrocarbon chain decreased the rate of conversion and yield for stearic acid with methanol, which was 90%. Maximum biodiesel production was achieved from coconut and soybean soap stocks and methanol (96%-98%), which showed conversions very close to those obtained from their respective fatty acids. Microwave irradiation reduced the reaction time from 6 to 1 h in the esterification reaction of fatty acids with butanol.

DESENVOLVIMENTO DE ENSAIO PARA ANÁLISE QUALITATIVA DE BIODIESEL EM MISTURAS DIESEL-BIODIESEL PARA APLICAÇÃO EM POSTOS REVENDEDORES DE COMBUSTÍVEIS

In this study, we developed a method for the visual detection of biodiesel in petrodiesel-biodiesel (BX) blends through the aminolysis of the methyl or ethyl esters of fatty acids that are found in biodiesel and that are absent from diesel and vegetable oils. This method is based on three reactional stages, which produce a dark red and easily visualized complex in the presence of biodiesel. In the absence of biodiesel, there is no dark red coloring, whereas in the presence of diesel or vegetable oil, there is a light red to yellow coloring. This simple, practical, inexpensive, and effective procedure may be applied by petrol stations to guarantee to consumers and resellers the presence of biodiesel in diesel blends, regardless of the BX blend's initial coloring or of the sulfur found in the diesel. In short, it ensures a safe fuel tank fill-up with BX blend.

Improving diquat efficacy on grasses by adding adjuvants to the spray solution before use

The effect of five adjuvants (non-ionic surfactant, paraffinic oil, vegetable oil, mixture of fatty acids methyl esters plus surfactant blend, and organosilicone) on diquat efficacy was assessed on poverty brome, sterile oat, and Italian ryegrass in field and pot experiments. All tank mixtures with diquat increased diquat efficacy from 50-54% to 77-98% as for fresh weight reduction, indicating significant enhancement of diquat efficacy on grasses. The increased efficacy was most likely attributed to better droplet retention and diffusion on the leaf surfaces. When combined with non-ionic surfactant, diquat showed slightly more rapid control of grass weeds (i.e. symptoms were visible within a few hours after application).