Activity and stability of lipase from Candida Antarctica after treatment in pressurized fluids.

Lipase B from Candida antarctica (CalB) is one of the biocatalysts most used in organic synthesis due to its ability to act in several medium, wide substrate specificity and enantioselectivity, tolerance to non-aqueous environment, and resistance to thermal deactivation. Thus, the objective of this work was to treat CalB in supercritical carbon dioxide (SC-CO2) and liquefied petroleum gas (LPG), and measure its activity before and after high-pressure treatment. Residual specific hydrolytic activities of 132% and 142% were observed when CalB was exposed to SC-CO2 at 35 â„ƒ, 75 bar and 1 h and to LPG at 65 â„ƒ, 30 bar and 1 h, respectively. Residual activity of the enzyme treated at high pressure was still above 100% until the 20th day of storage at low temperatures. There was no difference on the residual activity loss of CalB treated with LPG and stored at different temperatures over time. Greater difference was observed between CalB treated with CO2 and flash-frozen in liquid nitrogen (- 196 â„ƒ) followed by storage in freezer (- 10 â„ƒ) and CalB stored in freezer at - 10 â„ƒ. Such findings encourage deeper studies on CalB as well as other enzymes behavior under different types of pressurized fluids aiming at industrial application.

Lipases in liquid formulation for biodiesel production: Current status and challenges.

Enzymatic synthesis of biodiesel showed advantageous characteristics in relation to other technologies once it works under bland conditions, no generation of wastewater, no occurrence of saponifications reactions and production of a biodiesel with high quality. Although many researches still apply immobilized lipases, the high costs associated with this biocatalyst hamper the economic viability of the process. Lipases in free/soluble/liquid formulation employed to biodiesel production via hydroesterification reaction have attracted interest from researchers because they are more cost effective than the immobilized form, making the enzymatic route more competitive. In addition, soluble lipases present higher reaction rates, reducing the time required to obtain a satisfactory biodiesel yield. Despite the fact that already exist industrial plants producing biodiesel with the assistance of lipases in liquid formulation, results of researches show that the process still needs to overcome some drawbacks. This paper is a comprehensive and critical discussion on the publications where soluble lipases were applied on biodiesel synthesis, as well as the challenges that the technology faces and its current status in pilot and industrial applications.

Adsorption of methane by modified-biochar aiming to improve the gaseous fuels storage/transport capacity: process evaluation and modeling.

The CH4 storage by adsorption on activated carbons for natural gas handling has gained interest due to the appearance of lightweight materials with large surface areas and pore volumes. Consequently, kinetic parameters estimation of the adsorptive process can play a crucial role in understanding and scaling up the system. Concerning its versatility, banana peel (BP) is a biomass with potential for obtaining different products, such as biochar, a solid residue from the biomass' thermal decomposition of difficult disposal, where through an activation process, the material porous features are taken advantage to application as adsorbent of gaseous substances. This research reported data for the CH4 adsorption kinetic modeling by biochar from BP pyrolysis. The activated biochar textural characterization showed particles with fine mesoporous structure (pore diameter ranging between 29.39 and 55.62 Å). Adsorption kinetic analysis indicated that a modified pseudo-first-order model was the most suitable to represent the experimental data, with equilibrium adsorption of 28 mg g-1 for the samples activated with 20.0% vol wt.-1 of H3PO4 and pyrolysis at 500 °C. The equilibrium constant was consistent with the Freundlich isotherm model, suggesting a physisorption mechanism, and led to a non-ideal, reversible, and not limited to monolayer CH4 adsorption.

Identification of organic sulfur compounds in coal bitumen obtained by different extraction techniques using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometric detection.

The determination of organic sulfur compounds (OSC) in coal is of great interest. Technically and operationally these compounds are not easily removed and promote corrosion of equipment. Environmentally, the burning of sulfur compounds leads to the emission of SO(x) gases, which are major contributors to acid rain. Health-wise, it is well known that these compounds have mutagenic and carcinogenic properties. Bitumen can be extracted from coal by different techniques, and use of gas chromatography coupled to mass spectrometric detection enables identification of compounds present in coal extracts. The OSC from three different bitumens were tentatively identified by use of three different extraction techniques: accelerated solvent extraction (ASE), ultrasonic extraction (UE), and supercritical-fluid extraction (SFE). Results obtained from one-dimensional gas chromatography (1D GC) coupled to quadrupole mass spectrometric detection (GC-qMS) and from two-dimensional gas chromatography with time-of-flight mass spectrometric detection (GC × GC-TOFMS) were compared. By use of 2D GC, a greater number of OSC were found in ASE bitumen than in SFE and UE bitumens. No OSC were identified with 1D GC-qMS, although some benzothiophenes and dibenzothiophenes were detected by use of EIM and SIM modes. GC × GC-TOFMS applied to investigation of OSC in bitumens resulted in analytical improvement, as more OSC classes and compounds were identified (thiols, sulfides, thiophenes, naphthothiophenes, benzothiophenes, and benzonaphthothiophenes). The roof-tile effect was observed for OSC and PAH in all bitumens. Several co-elutions among analytes and with matrix interferents were solved by use of GC × GC.

Extraction of grape seed oil using compressed carbon dioxide and propane: extraction yields and characterization of free glycerol compounds.

The main objective of this work was to compare the extraction of grape seed oil with compressed carbon dioxide and propane on the extraction yields and chemical characteristics of free glycerol compounds. The experiments were performed in a laboratory scale unit in the temperature range of 30 to 60 degrees C and pressures from 60 to 254 bar. The results showed that propane is a more suitable solvent for grape seed oil extraction than carbon dioxide, as higher extractions yields and a very fast kinetic of extraction were achieved with this solvent. In relation to compressed carbon dioxide extractions, both temperature and density presented a very pronounced and positive effect on the extraction yield. The oils extracted were analyzed qualitatively and quantitatively with regard to the free glycerol compounds, mainly fatty acids, ethyl, and methyl esters. The results showed that these compounds are present in low concentration in vegetable oil (<3%) and that, in general, samples extracted with propane present a smaller amount of peaks of free glycerol compounds in the oil than samples extracted with carbon dioxide.

The use of ultrasound in the extraction of Ilex paraguariensis leaves: a comparison with maceration.

The objective of this work is to discuss the main parameters that influence the sonication extraction of Ilex paraguariensis leaves. For this purpose, the extraction time, solvent polarity, solvent volume, sample mass and particle size were evaluated. Results showed that the main variable affecting the extraction process was the solvent polarity. Though in a less extent, temperature and extraction time also demonstrated to be important parameters, while the other variables did not present a significant influence on the extraction yield. The extracts at the optimized condition were compared with those obtained by maceration, in terms of mass yield and chemical composition. The major compounds identified in the extracts were caffeine and palmitic acid. Some saturated hydrocarbons such as fatty acids, fatty acid methyl esters, phytosterols, and theobromine were also identified in the fractions.

Optimization of alkaline transesterification of soybean oil and castor oil for biodiesel production.

This article reports experimental data on the production of fatty acid ethyl esters from refined and degummed soybean oil and castor oil using NaOH as catalyst. The variables investigated were temperature (30-70 degrees C), reaction time (1-3 h), catalyst concentration (0.5-1.5 w/wt%), and oil-to-ethanol molar ratio (1:3-1:9). The effects of process variables on the reaction conversion as well as the optimum experimental conditions are presented. The results show that conversions >95% were achieved for all systems investigated. In general, an increase in reaction temperature, reaction time, and in oil-to-ethanol molar ratio led to an enhancement in reaction conversion, whereas an opposite trend was verified with respect to catalyst concentration.

Kinetics of enzyme-catalyzed alcoholysis of soybean oil in n-hexane.

This work investigated the production of fatty acid ethyl esters (FAEEs) from soybean oil using n-hexane as solvent and two commercial lipases as catalysts, Novozym 435 and Lipozyme IM. A Taguchi experimental design was adopted considering the variables temperature (35-65 degrees C), addition of water (0-10 wt/wt%), enzyme (5-20 wt/wt%) concentration, and oil-to-ethanol molar ratio (1:3-1:10). It is shown that complete conversion in FAEE is achieved for some experimental conditions. The effects of process variables on reaction conversion and kinetics of the enzymatic reactions are presented for all experimental conditions investigated in the factorial design.

Optimization of enzymatic production of biodiesel from castor oil in organic solvent medium.

We studied the production of fatty acid ethyl esters from castor oil using n-hexane as solvent and two commercial lipases, Novozym 435 and Lipozyme IM, as catalysts. For this purpose, a Taguchi experimental design was adopted considering the following variables: temperature (35-65 degrees C), water (0-10 wt/wt%), and enzyme (5-20 wt/wt%) concentrations and oil-to-ethanol molar ratio (1:3 to 1:10). An empirical model was then built so as to assess the main and cross-variable effects on the reaction conversion and also to maximize biodiesel production for each enzyme. For the system containing Novozym 435 as catalyst the maximum conversion obtained was 81.4% at 65 degrees C, enzyme concentration of 20 wt/wt%, water concentration of 0 wt/wt%, and oil-to-ethanol molar ratio of 1:10. When the catalyst was Lipozyme IM, a conversion as high as 98% was obtained at 65 degrees C, enzyme concentration of 20 wt/wt%, water concentration of 0 wt/wt%, and oil-to-ethanol molar ratio of 1:3.

Pressurized liquid extraction of mate tea leaves.

The objective of this work is to investigate the influence of process parameters on the pressurized liquid extraction (PLE) of Ilex paraguariensis leaves. A factorial 2(6-2) experimental design was employed using responses as the extraction yield and the chromatographic profile of the extracts. The extraction time, polarity of solvent, amount of sample, numbers of PLE cycles, flushing volume and extraction temperature were selected as independent variables (factors). Results obtained indicated that the solvent polarity was the most significant variable in the study, while the amount of sample and extraction temperature also showed significant effect. The other variables did not present significant influence in the yield of extraction. GC/MS analysis of the extract enabled the identification of saturated hydrocarbons, fatty acids, fatty acid methyl esters, phytosterols and theobromine in the extracts. Quantitative analysis of four compounds presented in the extracts (caffeine, phytol, vitamin E and squalene) was performed by the GC/MS in the SIM mode.

Thermodynamic modeling of ternary liquid-liquid systems with forming immiscibility islands

The aim of this work was to study the application of a stochastic algorithm to correlate the experimental data of island-type systems in ternary systems. Thermodynamic NRTL and UNIQUAC models were used to evaluate the activity coefficients. Results regarding the application of the stochastic algorithm were in good agreement with those presented in the current literature. However, generalization of the method proposed in the present work remained an intriguing and complex task so as to reach broad conclusions.

Chemical composition and antibacterial activity of Aloysia triphylla (L'Hérit) Britton extracts obtained by pressurized CO2 extraction

This study investigated the chemical composition of five different extracts of Aloysia triphylla and their activity against Aeromonas sp. The extracts were obtained from the dried leaves by pressurized CO2 extraction at 30, 50 and 70ºC, and 100, 150, and 200 bar, and analyzed by GC/FID and GC-MS. The antibacterial activity was assayed by the microdilution method. The tested microorganisms comprised seven Aeromonas isolates obtained from the kidney of infected silver catfish, Rhamdia quelen. The yield, chemical composition and antibacterial activity of the extracts were dependent on the extraction conditions. Mono and sesquiterpenoids were the major constituents of all the extracts and the highest extraction yield was obtained at 70ºC and 200 bar. A. triphylla presented moderate antibacterial activity against Aeromonas sp.

Chemical composition of mate tea leaves (Ilex paraguariensis): a study of extraction methods.

The objective of this work was to investigate the extraction of Ilex paraguariensis leaves by means of three extraction techniques: pressurized liquid extraction (PLE, also called accelerated solvent extraction--ASE), maceration, and sonication. Samples of mate tea leaves were collected from an experiment conducted under agronomic control at Indfistria e Comércio de Erva-Mate Barão LTDA, Brazil. Six solvents with increasing polarities (n-hexane, toluene, dichloromethane, ethyl acetate, acetone, and methanol) were used in this investigation. Chemical analysis of the extracts was performed by GC coupled with a mass spectrometer detector. The identification and quantification were accomplished by coinjections of certified standards. The results showed that no significant differences in the qualities of the extracts were noticed regarding the extraction methods. On the other hand, the PLE technique was found to be more effective for the extractions of caffeine, phytol, palmitic, and stearic acid. The use of PLE led to a significant decrease in the total extraction time, amount of solvent consumption, and manipulation of samples compared to maceration and ultrasound-assisted extraction methods.

Semi-volatile compounds variation among Brazilian populations of Ilex paraguariensis St. Hil

The use of compressed carbon towards extracting semi-volatile compounds present in maté leaves (Ilex paraguariensis St. Hil.) is due to the growing interest in mate constituents to develop new products in the cosmetic, pharmaceutical and food industries. The objective of this work was to assess the chemical distribution of semi-volatile compounds in 20 native populations of maté collected all over Brazil. The extracts of bulk samples (30 plants) of each population were obtained by the high-pressure carbon dioxide extraction technique, and analyzed by GC/MSD. The quantification of compounds (caffeine, theobromine, phytol, squalene, vitamin E, eicosane, pentatriacontane, and stigmasterol) showed significant variations within the different populations and compounds analyzed, which are not related to geographical origin or macroclimate characteristics. The results pointed out to the importance of genetic and local environmental factors on the chemical composition of this species.

A extração empregando dióxido de carbono a altas pressões em erva-mate (Ilex paraguariensis St. Hil.), tem sido justificada pelo crescente interesse desta matriz vegetal ou de parte de seus constituintes na formulação de novos produtos, tais como cosméticos e medicamentos, entre outros. Neste contexto, o objetivo do presente trabalho é avaliar a distribuição química de compostos semi-voláteis em 20 populações de erva-mate coletadas em toda área de distribuição desta espécie no Brasil. 30 plantas foram selecionadas para produzir a amostra de cada população. Os extratos de cada amostra foram obtidos por extração com dióxido de carbono a alta pressão e, posteriormente, foram analisados por CG/EM. A quantificação de alguns compostos semi-voláteis presentes nos extratos (cafeína, teobromina, fitol, esqualeno, vitamina E, eicosano, pentatriacontano e stigmasterol), apresentaram variações significativas entre as concentrações dos diferentes compostos analisados nas diferentes populações, os quais não estão relacionados com origem geográfica ou com características de macroclima. Os resultados apontam para a importância dos fatores genéticos e/ou fatores de microclima sobre a composição química desta espécie.

Evaluation of Origanum vulgare essential oil as antimicrobial agent in sausage

This work reports antimicrobial activity of oregano (Origanum vulgare) essential oil against several bacteria in sausage. The in vitro minimum inhibitory concentration (MIC) was determined for 9 selected aerobic heterotrofic bacteria. The antimicrobial activity of distinct concentrations of the essential oil on the basis of the highest MIC found was tested in a food system comprised of fresh sausage. Batch food samples were also inoculated with Escherichia coli with a fixed concentration and the time course of the product was evaluated with respect to the action of the different concentrations of essential oil. Sensory analysis were conducted, and results showed that the addition of oregano essential oil to sausage may be a promising route as bacteriostatic effect was verified for oil concentrations lower than the MIC.

O presente trabalho reporta resultados referentes à testes de atividade antimicrobiana do óleo essencial de orégano (Origanum vulgare) contra várias bactérias em lingüiça. A concentração inibitória mínima (CIM) foi determinada para 9 bactérias aeróbicas heterotróficas. Com base no maior valor encontrado da CIM, testou-se a atividade antimicrobiana para distintas concentrações do óleo essencial in lingüiça fresca. Amostras do sistema alimentar escolhido foram inoculadas com Escherichia coli numa determinada concentração e a evolução temporal do produto concernente ao crescimento microbiano foi monitorada avaliando-se o efeito das diferentes concentrações de óleos essencial aplicadas ao produto inoculado. Os resultados das análises microbiológica e sensorial mostraram que a adição do óleo essencial de orégano a linguiça fresca coloca-se como promissora tendo em vista os efeitos bacteriostáticos observados em baixas concentrações do óleo essencial, inferiores a CIM.