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Utilização da metodologia de superfície de resposta no desenvolvimento de um molho tipo Pesto visando a atividade antioxidante / Utilization of response surface methodology in the development of a Pesto sauce to maximize its antioxidant activityAfonso, Guilherme 06 September 2006 (has links)
Evidências recentes têm demonstrado que dietas com elevado conteúdo de vegetais, frutas e grãos podem reduzir o risco de diversas doenças não transmissíveis. As propriedades benéficas desses alimentos têm sido atribuídas, em grande parte, à presença de substâncias antioxidantes, que são capazes de diminuir os efeitos prejudiciais dos radicais livres. O objetivo deste trabalho foi desenvolver uma formulação de molho tipo Pesto, com base nas propriedades antioxidantes dos seus ingredientes principais: manjericão, castanha do Brasil e azeite de oliva extra virgem. A metodologia foi divida em duas fases: a primeira consistiu na avaliação da interação entre os componentes com atividade antioxidante (AA) presentes nos ingredientes principais do molho, realizada através da metodologia de superfície de resposta por modelagem de misturas. Foi utilizado um planejamento centróide simplex, no qual a resposta medida foi a atividade antioxidante dos extratos de diferentes polaridades obtidos das diferentes formulações. Utilizando-se o método DPPH (1,1-difenil-2-picrilhidrazil) e o sistema ß-caroteno/ácido linoléico, não foi encontrada interação entre os componentes com AA presentes nos ingredientes. Apesar dos modelos obtidos não descreverem adequadamente a variação dos resultados, o manjericão foi identificado como o ingrediente de maior contribuição para a AA total do molho. Foi realizada análise sensorial para determinar a formulação melhor aceita dentre as possibilidades obtidas. A segunda fase consistiu em submeter a formulação determinada na fase 1 às análises de composição centesimal, quantificação dos compostos fenólicos totais e quatro métodos in vitro de avaliação da AA: método do poder redutor, sistema ß-caroteno/ácido linoléico, DPPH e ensaio em meio lipídico pelo aparelho Rancimat®. A formulação final pode ser considerada como uma boa fonte de antioxidantes naturais e portanto fazer parte de uma dieta saudável. / Recent evidences have shown that high consumption of vegetables, fruits and grains can reduce the risk of non-communicable diseases. The healthy properties of these foods have been related mostly to the presence of antioxidants, substances which are known as capable of decreasing the harmful effects of free radicals. The objective of this work was to develop a Pesto sauce formulation, based on the antioxidant properties of its main ingredients: sweet basil, Brazil nut and extra-virgin olive oil. The methodology was divided in two phases: The first one consisted in the evaluation of the interaction between the components with antioxidant activity (AA) present in the sauce\'s main ingredients, applying the response surface methodology with a mixture model. A centroid simplex plan was used, in which the response measured was the AA of the extracts of different polarities from the different formulations. By using the DPPH (1,1-diphenyl-2-picryhydrazyl) method and the ß-carotene/linoleic acid system, no interaction between the components with AA was detected. Although the models could not describe properly the response variation, sweet basil was identified as the main responsible for the total AA of the sauce. Sensory analysis was conducted to determine the most accepted formulation among the possibilities. The second phase consisted in submitting the formulation obtained in phase 1 to centesimal composition analysis, quantification of total phenolics and four in vitro AA methods: reducing power, DPPH method, ß-carotene/linoleic acid system and the Rancimat® method. The final formulation may be considered a good source of natural antioxidants and therefore be part of a healthy diet.
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Otimização para a obtençao de extrato aquoso de tremoço branco (Lupinus albus L.) adicionado de suco de pitanga /Botaro, Juliana Aparecida. January 2010 (has links)
Orientador: José Paschoal Batistuti / Banca: Rubens Monti / Banca: Alice Yoshiko Tanaka / Resumo: Recentemente, a indústria de alimentos está preocupada em desenvolver novos produtos, usando ingredientes inovadores, que promovam benefícios à saúde. O uso de proteínas de leguminosas como uma alternativa para a proteína animal tem sido estudada. O tremoço branco (Lupinus albus L.) apresenta elevada concentração de proteína e óleo, principalmente ácidos graxos insaturados e poliinsaturados, fibra alimentar, açúcares e vitaminas B1 e B2. Por outro lado, o tremoço não pode ser consumido diretamente porque possui alcaloides, que além de serem tóxicos, atribuem gosto amargo ao grão. Como a maioria dos alcaloides é solúvel em água, a quantidade de alcaloide do grão pode ser diminuída através de água corrente, fervente ou salmoura. Sucos de frutas são bastante consumidos no Brasil, especialmente no verão, não somente pelo sabor, mas como fonte de hidratação e por serem ricos em nutrientes. Os sucos de frutas tropicais conquistam cada vez mais o mercado consumidor, sendo o Brasil, um dos principais produtores. A pitanga, fruto da pitangueira (Eugenia uniflora L.) é uma planta frutífera nativa do Brasil (das regiões Sul e Sudeste e que tem se adaptado favoravelmente às condições climáticas e edáficas da região Nordeste), da Argentina e do Uruguai. A pitanga é uma fruta cuja polpa apresenta excelentes condições para industrialização, devido ao seu alto rendimento, aroma agradável e sabor exótico. O objetivo do presente estudo foi o de verificar, através da metodologia de superfície de resposta, as melhores condições para a utilização simultânea de extrato aquoso de tremoço branco e de suco tropical de pitanga, no desenvolvimento de uma bebida. Para tanto, as variáveis independentes foram representadas pelo volume de extrato aquoso de tremoço (mL) e pelo volume de suco de pitanga... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Recently, the food industry is concerned about developing new products, using innovative ingredients that promote health benefits. The use of vegetable protein as an alternative to animal protein is being studied. The white lupine (Lupinus albus L.) has high concentrations of protein and oil, especially non saturated fatty acids and polynonsaturated fats, dietary fiber, sugars and vitamins B1 and B2. On the other hand, the lupine bean can't be consumed straight because it has alkaloids which besides being toxic, add a bitter taste to the bean. As most alkaloids are water soluble, the amount of alkaloid in the beans can be reduced by running water, boiling or brine. Fruit juices are widely consumed in Brazil, especially in the summer, not only for their flavor, but as a source of hydration and because they are rich in nutrients. The tropical fruit juices are conquering the market more and more, with Brazil being one of the main producers in the world. The Pitanga (Eugenia uniflora L.) is the fruit of the Pitangueira, a native plant of southern Brazil (which has adapted positively to weather and soil conditions in the country's Northeast), Argentina and Uruguay. Pitanga is a fruit which pulp presents excellent conditions for industrialization, due to its high yield, pleasant aroma and exotic flavor. The aim of the present study was to verify, through the response surface methodology, the optimum conditions for the combined use of aqueous extract of white lupine and tropical pitanga juice in the development of a drink. Therefore, the independent variables were represented by the volume of aqueous extract of lupine (mL) and by the volume of pitanga juice (mL). The dependent variables (responses) were obtained through sensory test of acceptance ("appearance", "aroma", "taste" and "overall acceptability"). The combined... (Complete abstract click electronic access below) / Mestre
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[en] FUNDAMENTAL ASPECTS OF BORON REMOVAL FROM WASTEWATERS BY ELECTROCOAGULATION METHOD / [pt] ASPECTOS FUNDAMENTAIS DA REMOÇÃO DE BORO CONTIDO EM EFLUENTES AQUOSOS POR ELETROCOAGULAÇÃOTHIAGO DA SILVA RIBEIRO 01 February 2019 (has links)
[pt] Compostos de boro são utilizados na indústria metalúrgica, microeletrônica, de vidros, na agricultura, etc. Esse elemento é um micronutriente essencial no desenvolvimento de microrganismos, plantas, animais e humanos. No entanto, pode ser tóxico em grandes concentrações e por isso necessita ser removido de águas e efluentes. No Brasil, o limite padrão é de 0,5mg/L para águas doces de classe I e II, estabelecido pela resolução do Conama 357/2005. Por sua vez, a resolução do Conama 430/2011 estabelece um padrão de lançamento de efluentes de 5mg/L. A presente dissertação tem como objetivo geral estudar a remoção de boro por eletrocoagulação para o tratamento de águas e efluentes contendo boro, utilizando uma célula com um arranjo de 4 eletrodos de alumínio (2 catodos e 2 anodos) monopolares em paralelo. Os resultados obtidos mostram que o processo de eletrocoagulação é uma alternativa viável para a remoção de boro, e alcança eficiências em torno de 70 por cento (em pH inicial igual à 4; densidade de corrente igual à 18,75mA/cm2 e tempo de eletrólise igual à 90min). O modelo cinético que melhor descreve a remoção de boro foi o de pseudo-primeira ordem. O modelo de Langmuir se ajustou muito bem aos dados experimentais obtidos. O valor de qm obtido pelo modelo de Langmuir refletiu a elevada capacidade de adsorção máxima (qm é igual à 334mg/g). Através das análises por Microscopia Eletrônica de Varredura (MEV) e por Espectroscopia de Energia Dispersiva (EDS) na superfície dos eletrodos, observou-se a presença de corrosão do tipo localizada nos catodos e a corrosão do tipo uniforme nos anodos. A morfologia do lodo produzido no processo de eletrocoagulação foi analisada por MEV, indicando a presença de uma morfologia heterogênea na superfície, enquanto que a análise por Difração de Raios-X (DRX) apresentou picos largos característicos de um material amorfo e a fase de alumínio predominante foi a boehmita, AlO(OH), finalmente, através da análise por Espectroscopia por Perda de Energia de Elétrons (EELS) foi possível a detecção do boro no lodo, além da detecção de alumínio e de oxigênio. Diante dos resultados obtidos no estudo de otimização a partir da Metodologia de Superfície de Resposta (RSM) constatou-se que o desenvolvimento de um modelo matemático por análise de regressão possibilitou a avaliação do efeito das variáveis independentes (densidade de corrente, pH inicial e tempo de eletrólise) e as suas interações na remoção de boro. / [en] Boron compounds are used in the metallurgical industry, microelectronics, glassware, agriculture, etc. This element is an essential micronutrient in the development of microorganisms, plants, animals and humans. However, it can be toxic in high concentrations and therefore needs to be removed from water and effluent. In Brazil, the standard limit is 0.5mg/L for Class I and II freshwaters, established by Conama Resolution 357/2005. In turn, the Conama 430/2011 resolution establishes an effluent discharge standard of 5mg/L. The present dissertation aims to study the removal of boron by electrocoagulation for the treatment of water and effluents containing boron, using a cell with an arrangement of 4 monopolar aluminum electrodes (2 cathodes and 2 anodes) in parallel. The results show that the electrocoagulation process is a viable alternative for the removal of boron and reaches efficiencies around 70 per cent (at initial pH equals to 4, current density equals to 18.75mA/cm2 and electrolysis time equals to 90min). The kinetic model that best describes the removal of boron was pseudo-first order. The Langmuir model fitted very well to the experimental data obtained. The value of qm obtained by the Langmuir model reflected the high maximum adsorption capacity (qm equals to 334mg/g). Through the analysis by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) on the surface of the electrodes, it was observed the presence of pitting corrosion in the cathodes and uniform corrosion in the anodes. The morphology of the sludge produced in the electrocoagulation process was analyzed by SEM, indicating the presence of a heterogeneous surface morphology, while the X-ray diffraction (XRD) analysis showed broad peaks characteristic of an amorphous material and the predominant aluminum phase was boehmite, AlO(OH), finally, through the Electron Energy Loss Spectroscopy (EELS) analysis, it was possible to detect boron in the sludge, as well as aluminum and oxygen. In view of the results obtained in the optimization study from the Response Surface Methodology (RSM), it was verified that the development of a mathematical model by regression analysis made possible the evaluation of the effect of the independent variables (current density, initial pH and time of electrolysis) and their interactions in the removal of boron.
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Potencial antioxidante de extratos de especiarias em sistemas modelo e na estabilidade oxidativa do óleo de soja / Antioxidant activity of spices extracts in model systems and in the oxidative stability of soybean oilSichieri, Ana Paula Marques Pino 18 October 2013 (has links)
A degradação oxidativa dos lipídeos é um fator preponderante que limita a vida útil dos alimentos, reduzindo suas qualidades nutricionais e organolépticas. A utilização de antioxidantes durante o processo de fabricação pode diminuir consideravelmente a extensão da oxidação lipídica, desencadeada pela reação de radicais livres. A crescente preocupação pelo consumo de alimentos mais saudáveis e livres de aditivos sintéticos tem recebido maior atenção pelas indústrias, que atualmente tem procurado por alternativas mais naturais, como o uso de antioxidantes provenientes de especiarias, como uma forma promissora de substituição dos compostos sintéticos. O objetivo deste trabalho foi estudar as condições de obtenção de extratos hidroalcoólicos de cravo (Syzygium aromaticum), canela (Cinnamomum verum) e pimenta dedo-de-moça (Capsicum annuum) e sua aplicação em óleos de soja refinado, armazenado em embalagens de vidro, em comparação com amostras adicionadas de antioxidante sintético TBHQ e amostras livres de antioxidantes (controle), durante sete meses, simulando a comercialização em supermercados. Foram verificados também as propriedades antioxidantes dos extratos de especiarias produzidos nas condições selecionadas através das metodologias de DPPH e ABTS. O estudo do efeito da temperatura de extração e do grau de hidratação do etanol sobre o rendimento de compostos fenólicos totais dos extratos destas especiarias foi realizado com aplicação de planejamento experimental e metodologia de superfícies de resposta. As condições para uma extração eficiente dos compostos fenólicos do cravo, da canela e da pimenta foram o emprego de etanol a 49,5 % (v/v). As melhores temperaturas estiveram entre 45 a 50 °C para o cravo e canela, e 60 °C para a pimenta. Os extratos de cravo, canela e pimenta dedo-de-moça preparados nas condições otimizadas, foram adicionados nas proporções de 50 mg kg-1, 100 mg kg-1, 150 mg kg-1 e 200 mg kg-1 às amostras de óleo de soja refinado e submetido a um teste acelerado em estufa a 65 °C juntamente com amostras adicionadas nas mesmas proporções de TBHQ e amostras isentas de antioxidantes (controle), para verificação da concentração mais eficiente no retardar a oxidação. Em seguida, após os resultados do teste de estufa, os óleos adicionados de 100 mg kg-1 de extratos, TBHQ, e isento de antioxidantes foram acondicionados em embalagens de vidro transparente de 250 mL e armazenados sob condições de comercialização (incidência de luz fluorescente por 15 horas / 24 horas e 331,71 Lux). Os resultados de Índice de Peróxido, Acidez e Absortividade na faixa do ultravioleta evidenciaram que os extratos foram capazes de oferecer proteção antioxidante ao óleo de soja refinado em diferentes níveis, sendo que o tratamento adicionado de extrato de cravo foi o que mais se destacou na inibição da oxidação lipídica do óleo de soja, seguido do extrato adicionado de canela e pimenta (p<0,05). / Lipid deterioration is a major cause of shorter food shelf life, reducing its nutritional and organoleptical quality. The use of antioxidants during the manufacturing process can significantly decrease the extent of lipid oxidation reactions triggered by free radicals. The growing concern about the consumption of healthier foods and free from synthetic additives has received increased attention by the industry, which is currently looking for more natural alternatives, such as the use of antioxidants from herbs and spices, as a promising replacement of synthetic compounds. The objective of this work was to study the conditions for obtaining hydroalcoholic extracts of cloves (Syzygium aromaticum), cinnamon (Cinnamomum verum) and red pepper (Capsicum annuum) and its application in soybean oil refined, stored in glass containers, compared with samples added of synthetic antioxidant TBHQ and samples free antioxidant (control) during 7 months simulating marketing conditions in supermarkets. Extracts were analyzed by DPPH and ABTS methods. The study of the effect of extraction temperature and the degree of hydration of ethanol on the yield of total phenolic compounds of the extracts of these spices was carried out with application of experimental design and response surface methodology. The best solvent concentration for efficient extraction of phenolic compounds from clove, cinnamon and pepper was 49.5% ethanol (v / v). The best temperatures were between 45 and 50°C for cloves and cinnamon, and 60 ° C for pepper. The extracts of clove, cinnamon and red pepper prepared under optimized conditions were added in concentration of 50 mg kg-1 , 100 mg kg-1, 150 mg kg-1 and 200 mg kg-1 to samples of refined soybean oil and subjected to an accelerated storage test at 65°C with samples containing the same concentrations of TBHQ and samples free of antioxidant (control) in order to check the most efficient concentrations to slow the oxidation. The best extracts concentration 100 mg kg-1 from the Schaal oven test was added to oil packed in glass containers against oil with 100 mg kg-1 of TBHQ, and oils free of antioxidants and stored under normal commercialization conditions (fluorescence light exposure for 15 hours / 24 hours and 333,71 Lux). Peroxide, acid values and absorptivity in the ultraviolet range showed that the extracts were able to offer antioxidant protection to soybean oil at different levels. Clove extract, showed the best performance in the inhibition soybean oil oxidation, followed by cinnamon and pepper (p<0,05).
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Investigation Of Bioprocess Parameters For Glucose Isomerase Production By Bacillus ThermoantarcticusHaykir, Isik 01 September 2004 (has links) (PDF)
In this study, the effects of bioprocess parameters on glucose isomerase roduction by Bacillus thermoantarcticus (DSMZ 9572) were investigated. For his purpose, firstly, in laboratory scale shake-bioreactors, a defined medium
was designed in terms of its carbon and nitrogen sources, to achieve the highest glucose isomerase activity. Optimum concentrations of medium components were determined by a statistical approach, namely Response Surface Methodology (RSM). RSM defined the relationship between the response, glucose isomerase activity and the independent variables, medium components. The highest glucose isomerase volumetric activity was obtained as 1630 U L-1 in the optimized medium containing 10.64 kg m-3 xylan, 5.66 kg
m-3 yeast extract, 5.92 kg m-3 (NH4)2SO4, 0.25 kg m-3 MgSO4.7H2O, 0.001 kg m-3 FeSO4.7H2O, 0.001 kg m-3 ZnSO4.7H2O , 0.000075 kg m-3 MnSO4. H2O,
and 0.00001 kg m-3 CuSO4.5H2O at conditions: pH0= 6.0, T=55° / C, N=200 min-1. Then by using the designed medium, pH and oxygen transfer conditions of the bioprocess were investigated in 3.0 dm3 pilot scale bioreactor. The effect
of pH was analyzed at pH=6 uncontrolled and controlled operations with the following conditions: air inlet rate of Q0/VR=0.5 vvm and agitation rate of N=500 min-1. The effects of oxygen transfer parameters were examined, at
pH=6 controlled condition, at an air inlet rate of Q0/VR=0.5 vvm and the agitation rates of N=300,500,750 min-1. The variations in glucose isomerase activity, cell, amino acid and organic acid concentrations with the cell cultivation time, specific cell growth rate, the oxygen uptake rate, the liquid
phase coefficient by using the dynamic method, maintenance coefficient for oxygen and yield coefficients were determined. The highest glucose isomerase volumetric activity and cell concentration, 1838 U L-1 and 2.26 kg m-3 at the
24th of the cell cultivation were attained at 0.5 vvm, 500 min 1 and pH=6 uncontrolled operation.
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Path Optimization Of Flapping Airfoils Based On Unsteady Viscous Flow SolutionsKaya, Mustafa 01 February 2008 (has links) (PDF)
The flapping path of a single airfoil and dual airfoils in a biplane configuration is optimized for maximum thrust and/or propulsive efficiency. Unsteady, low speed viscous flows are computed using a Navier-Stokes solver in a parallel computing environment. A gradient based algorithm and Response Surface Methodology (RSM) are employed for optimization. The evaluation of gradient vector components and the design of experiments for RSM, which require unsteady solutions, are also carried out in parallel. Parallel computations are performed using Parallel Virtual Machine (PVM) library. First, a single airfoil undergoing a combined sinusoidal or non-sinusoidal pitching and plunging motion is studied. The non-sinusoidal flapping motion is described using an elliptic curve or Non-Uniform Rational B-Splines
(NURBS). It is shown that the thrust generation may significantly
be increased in comparison to the sinusoidal flapping motion. For
a high thrust, the airfoil stays at high effective angle of attack
values during the upstroke and the downstroke, and the effective pitching occurs at minimum and maximum plunge positions. Secondly, the optimization of sinusoidal and non-sinusoidal flapping paths of dual airfoils is considered. Moving and deforming overset grids are used for computations. The deforming overset grids remove the restrictions on the flapping motion, and improve the optimization results obtained earlier. At low flapping frequencies, an airfoil in a biplane configuration produces more thrust than a single airfoil. Yet, at high frequencies the airfoil in biplane configuration produces less thrust at a significantly lower efficiency than the single airfoil.
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Simulation-Based Robust Revenue Maximization Of Coal Mines Using Response Surface MethodologyNageshwaraniyergopalakrishnan, Saisrinivas January 2014 (has links)
A robust simulation-based optimization approach is proposed for truck-shovel systems in surface coal mines to maximize the expected value of revenue obtained from loading customer trains. To this end, a large surface coal mine in North America is considered as case study. A data-driven modeling framework is developed and then applied to automatically generate a highly detailed simulation model of the mine in Arena. The framework comprises a formal information model based on Unified Modeling Language (UML), which is used to input mine structural as well as production information. Petri net-based model generation procedures are applied to automatically generate the simulation model based on the whole set of simulation inputs. Then, factors encountered in material handling operations that may affect the robustness of revenue are then classified into 1) controllable; and 2) uncontrollable categories. While controllable factors are trucks locked to routes, uncontrollable factors are inverses of summation over truck haul, and shovel loading and truck-dumping times for each route. Historical production data of the mine contained in a data warehouse is used to derive probability distributions for the uncontrollable factors. The data warehouse is implemented in Microsoft SQL, and contains snapshots of historical equipment statuses and production outputs taken at regular intervals in each shift of the mine. Response Surface Methodology is applied to derive an expression for the variance of revenue as a function of controllable and uncontrollable factors. More specifically, 1) first order and second order effects for controllable factors, 2) first order effects for uncontrollable factors, and 3) two factor interactions for controllable and uncontrollable factors are considered. Latin Hypercube Sampling method is applied for setting controllable factors and the means of uncontrollable factors. Also, Common Random Numbers method is applied to generate the sequence of pseudo-random numbers for uncontrollable factors in simulation experiments for variance reduction between different design points of the metamodel. The variance of the metamodel is validated using leave-one-out cross validation. It is later applied as an additional constraint to the mathematical formulation to maximize revenue in the simulation model using OptQuest. The decision variables in this formulation are truck locks only. Revenue is a function of the actual quality of coal delivered to each customer and their corresponding quality specifications for premiums and penalties. OptQuest is an optimization add-on for Arena that uses Tabu search and Scatter search algorithms to arrive at the optimal solution. The upper bound on the variance as a constraint is varied to obtain different sets of expected value as well as variance of optimal revenue. After comparison with results using OptQuest with random sampling and without variance expression of metamodel, it has been shown that the proposed approach can be applied to obtain the decision variable set that not only results in a higher expected value but also a narrower confidence interval for optimum revenue. According to the best of our knowledge, there are two major contributions from this research: 1) It is theoretically demonstrated using 2-point and orthonormal k-point response surfaces that Common Random Numbers reduces the error in estimation of variance of metamodel of simulation model. 2) A data-driven modeling and simulation framework has been proposed for automatically generating discrete-event simulation model of large surface coal mines to reduce modeling time, expenditure, as well as human errors associated with manual development.
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Lipase selection and application for fatty acid ester synthesis / Lipazių atranka ir taikymas riebalų rūgščių esterių sintezeiŠinkūnienė, Dovilė 10 February 2014 (has links)
Lipases are widely researched enzyme group because of their ability to catalyze a wide range of synthesis reactions. The aim of this doctoral thesis was to study and optimize fatty acid ester synthesis using lipases. The influence of enzyme choice, its preparation (immobilization), choice of substrates and reaction conditions on fat hydrolysis, biodiesel and phenethyloctanoate (flavour ester) synthesis reaction course and yield was studied. Enterobacter aerogenes lipase, which was developed in Lithuania, was immobilized and its properties were determined for the first time. Commercial lipases were used for hydrolysis and synthesis reactions, the influence of reaction parameters was determined using response surface methodology, and so the yield was optimized. Silica gel was found to be a promising reaction additive for acyl group migration catalysis in biodiesel synthesis reaction. Different lipase specificities towards different acylglycerol classes and regioisomers varied greatly; on the basis of this knowledge two-step biodiesel synthesis catalysis was proposed. / Lipazių atranka ir taikymas riebalų rūgščių esterių sintezei Lipazės yra intensyviai tiriama fermentų grupė dėl jų gebos katalizuoti platų spektrą sintezės reakcijų. Disertacinio darbo tikslas buvo ištirti ir optimizuoti riebalų rūgščių esterių sintezės, panaudojant lipazes, būdus. Tirta fermento preparato paruošimo (imobilizavimo), fermento bei substratų pasirinkimo bei reakcijos sąlygų ir priedų įtaka riebalų hidrolizės, biodyzelino, fenetiloktanoato (kvapiojo esterio) sintezės reakcijų eigai ir išeigai. Pirmą kartą ištirtos Lietuvoje paruoštos Enterobacter aerogenes lipazės savybės, ji imobilizuota ant gamtinės kilmės nešiklių. Komercinių lipazių katalizuojamų reakcijų sąlygų įtakai nustatyti ir reakcijos išeigai optimizuoti naudota atsako paviršiaus metodologija. Tiriant reakcijos priedų įtaką acilgrupės migracijai ir biodyzelino sintezės reakcijai, nustatyta, kad perspektyvus priedas yra silikagelis. Lipazių specifiškumas ženkliai skiriasi skirtingoms acilglicerolių klasėms ir regioizomerams, šių žinių pagrindu buvo pasiūlyta dviejų etapų biodyzelino sintezės katalizė.
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Lipazių atranka ir taikymas riebalų rūgščių esterių sintezei / Lipase selection and application for fatty acid ester synthesisŠinkūnienė, Dovilė 10 February 2014 (has links)
Lipazės yra intensyviai tiriama fermentų grupė dėl jų gebos katalizuoti platų spektrą sintezės reakcijų. Disertacinio darbo tikslas buvo ištirti ir optimizuoti riebalų rūgščių esterių sintezės, panaudojant lipazes, būdus. Tirta fermento preparato paruošimo (imobilizavimo), fermento bei substratų pasirinkimo bei reakcijos sąlygų ir priedų įtaka riebalų hidrolizės, biodyzelino, fenetiloktanoato (kvapiojo esterio) sintezės reakcijų eigai ir išeigai. Pirmą kartą ištirtos Lietuvoje paruoštos Enterobacter aerogenes lipazės savybės, ji imobilizuota ant gamtinės kilmės nešiklių. Komercinių lipazių katalizuojamų reakcijų sąlygų įtakai nustatyti ir reakcijos išeigai optimizuoti naudota atsako paviršiaus metodologija. Tiriant reakcijos priedų įtaką acilgrupės migracijai ir biodyzelino sintezės reakcijai, nustatyta, kad perspektyvus priedas yra silikagelis. Lipazių specifiškumas ženkliai skiriasi skirtingoms acilglicerolių klasėms ir regioizomerams, šių žinių pagrindu buvo pasiūlyta dviejų etapų biodyzelino sintezės katalizė. / Lipases are widely researched enzyme group because of their ability to catalyze a wide range of synthesis reactions. The aim of this doctoral thesis was to study and optimize fatty acid ester synthesis using lipases. The influence of enzyme choice, its preparation (immobilization), choice of substrates and reaction conditions on fat hydrolysis, biodiesel and phenethyloctanoate (flavour ester) synthesis reaction course and yield was studied. Enterobacter aerogenes lipase, which was developed in Lithuania, was immobilized and its properties were determined for the first time. Commercial lipases were used for hydrolysis and synthesis reactions, the influence of reaction parameters was determined using response surface methodology, and so the yield was optimized. Silica gel was found to be a promising reaction additive for acyl group migration catalysis in biodiesel synthesis reaction. Different lipase specificities towards different acylglycerol classes and regioisomers varied greatly; on the basis of this knowledge two-step biodiesel synthesis catalysis was proposed.
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Supercritical Carbon Dioxide Extraction Of Apricot Kernel OilOzkal, Sami Gokhan 01 March 2004 (has links) (PDF)
The purpose of this research was to determine the solubility of apricot (Prunus armeniaca L.) oil in supercritical carbon dioxide (SC-CO2), effects of parameters (particle size, solvent flow rate, pressure, temperature and co-solvent (ethanol) concentration) on extraction yield and to investigate the possibility of fractionation.
Solubility, increased with pressure and increased with temperature above the crossover pressure, which was found between 200 and 300 bar, and decreased with temperature below the crossover pressure. Appropriate models were fitted to data.
Extraction of apricot kernel oil occurred in two extraction periods as fast and slow extraction periods. Most of the oil was extracted in the fast extraction period and the oil recovered in the slow extraction period was negligible. Extraction yield increased with decrease in particle size and recovery of more than 99 % of the oil was possible if particle diameter decreased below 0.425 mm. Extraction rate increased with increase in flow rate, pressure, temperature and ethanol concentration. The volume mass transfer coefficient in the fluid phase changed between 0.6 and 3.7 /min, whereas the volume mass transfer coefficient in the solid phase changed between 0.00009 and 0.00048 /min.
Extraction yield at 15 min for particle diameter smaller than 0.85 mm was formulated as a function of solvent flow rate, pressure, temperature, and ethanol concentration by using Response Surface Methodology. According to the model yield was highest (0.26 g /g) at 4 g/min flow rate, 60 oC, 450 bar and 3 % ethanol concentration. Fractionation was not possible at significant levels.
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