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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Amido Phosphine Complexes of Zinc, Nickel, and Aluminum: Synthesis, Structure, and Reactivity

Lee, Wei-yin 22 July 2004 (has links)
none
82

Amido Phosphine Complexes of Zirconium, Hafnium, Nickel, and Palladium : Synthesis, Structure, and Reactivity

Chien, Pin-Shu 06 September 2005 (has links)
A series of bi- and tri-dentate amido phosphine ligands H[Ph-PNP] (bis(2-diphenylphosphinophenyl)amine), H[iPr-PNP] (bis(2-diisopropylphosphino- phenyl)amine), H[Cy-PNP] (bis(2-dicyclohexylphosphinophenyl)amine), H[iPr-NP] (N-(2-diphenylphosphinophenyl)-2,6-diisopropylaniline), and H[Me-NP] (N-(2-diphenylphosphinophenyl)-2,6-dimethylaniline) have been synthesized in high yield. Lithiation of these compounds with n-BuLi in ethereal solutions afforded the corresponding lithium complexes. The metathetical reactions of MCl4(THF)2 (M = Zr, Hf) with [iPr-NP]Li(THF)2 or [Me-NP]Li(THF)2 in toluene produced the corresponding [iPr-NP]MCl3(THF) and [Me-NP]2MCl2, respectively, in high yield. In contrast, attempts to prepare [Me-NP]MCl3(THF) and [iPr-NP]2MCl2 led to the concomitant formation of mono- and bis-ligated complexes, from which purification proved rather ineffective. The solution and solid-state structures of [iPr-NP]MCl3(THF) and [Me-NP]2MCl2 were studied by multinuclear NMR spectroscopy and X-ray crystallography. Treatment of PdCl2(PhCN)2 with [iPr-NP]Li(THF)2 in THF afforded dimeric {[iPr- NP]PdCl}2, which was reacted with tricyclohexylphosphine to produce [iPr-NP]PdCl(PCy3). The two phosphorus donors in [iPr-NP]PdCl(PCy3) are mutually cis as indicated by the solution NMR and X-ray crystallographic studies. Both {[iPr-NP]PdCl}2 and [iPr-NP]PdCl(PCy3) are highly active catalyst precursors for Suzuki coupling reactions of a wide array of aryl halides, including those featuring electronically deactivated and sterically hindered characteristics. The metathetical reaction of NiCl2(DME) (DME = dimethoxyethane) with [iPr-PNP]Li(THF) and [Cy-PNP]Li(THF), respectively, produced the diamagnetic nickel complexes [iPr-PNP]NiCl and [Cy-PNP]NiCl. These nickel chloride complexes were reacted with Grignard reagents to afford thermally stable nickel alkyl and aryl complexes [iPr-PNP]NiR and [Cy-PNP]NiR (R = Me, Et, n-Bu, Ph). A series of divalent nickel alkoxo, amido, thiolate complexes [iPr-PNP]NiX and [Cy-PNP]NiX (X = OPh, NHPh, SPh) were also easily prepared. Reaction of H[Ph-PNP] with Ni(COD)2 (COD = cycloocta-1,5-diene) produced the transient [Ph-PNP]NiH, which underwent COD insertion to give [Ph-PNP]Ni(£b1- cyclooctenyl). Instead, reactions of Ni(COD)2 with H[iPr-PNP] and H[Cy-PNP], respectively, afforded isolable diamagnetic complexes [iPr-PNP]NiH and [Cy-PNP]NiH without alkene insertion. The reactivity of these nickel hydride complexes was investigated.
83

Aluminum and Palladium Complexes Containing Amido Phosphine Ligands: Synthesis, Structure, and Reactivity

Huang, Mei-hui 26 August 2008 (has links)
none
84

Preparation and Structural Characterization of Metal Complexes Containing a Chelating Phenolato or Amido Ligand

Chen, Han-Sheng 26 December 2008 (has links)
The Complexes {[O3P]AlMe}Ag and {[O3P]AlMe}Tl have been synthesized and characterized successfully. The structures of {[O3P]AlMe}Ag and {[O3P]AlMe}Tl were compared with the reported {[O3P]AlMe}Li(DME)3. The 31P NMR showed that soft nature of Ag and Tl ions in {[O3P]AlMe}Ag and {[O3P]AlMe}Tl respectively is interacted with P atom of phenolato ligand and the hard Li ion did not interact with P atom. The reaction of H3[O3P] with YCl3 at RT gave [O3PH]YCl. This is confirmed by 1H NMR technique. The complexes {[O3P]Zn}2Zn(THF)2 and {[OPO]Zn}2 were prepared by the reaction of Zn salt with [O3P]3- and [OPO]2- respectively in excellent yield and characterized by 1H NMR spectroscopy. The X-ray structure of complex {[O3P]Zn}2Zn(THF)2 reveals that it is formed as trimer. We have prepared two thallium complexes derived from diarylamido-based PNP ligands and TlOTf. 31P{1H} NMR revealed that two phosphine atoms in PNP ligand is coordinated with metal Tl center. The palladium-catalyzed aryl amination of 1-bromo-2-chlorobenzene with 2,6-diiso- propylaniline quantitatively produces N-(2-chlorophenyl)-2,6-diisopropylaniline, H[iPrAr- NCl]. Deprotonation of H[iPrAr-NCl] with 1 equiv of n-BuLi in toluene at -35 ¢XC produced cleanly [iPrAr-NCl]Li. Subsequent recrystallization of [iPrAr-NCl]Li in diethyl ether generated the bis(ether) adduct [iPrAr-NCl]Li(OEt2)2. An X-ray study of [iPrAr-NCl]Li- (OEt2)2 showed it to be a four-coordinate species with the coordination of the chlorine atom to the lithium center.
85

Syntheses and Reactivity Studies of Transition Metal Complexes Containing Chelating Amido Ligands

Lee, Wei-Ying 29 December 2008 (has links)
1. Benzene C-H Activation by Nickel(II) and Platinum(II) Complexes of Chelating Diarylamido Phosphine Ligands We have demonstrated an efficient intermolecular benzene C-H activation process mediated by Ni(II) complexes of ([Me-NP-iPr]Ni(L)(R)(L = Pyridine, 2,4-Lutidine, PMe3) and [iPr-NP-Ph]Ni(PMe3)(R) (R = Me, CH2SiMe3). When Lewis base is PMe3 or substituent is CH2SiMe3 more reactivity is observed. The amido diphosphine complexes [iPr-PNP]PtOTf effectively activate the benzene C-H bond in the presence of an appropriate Lewis base(NEt3 or DABCO). 2. Metal Complexes of Amido Phosphine Ligand Bearing Unsymmetric Donor Atom: Syntheses, Structures and Reactivities A series of [Ph-PNN]Ni(II)R (R = Me, Et, Ph, CH2Ph) complexes containing £]-hydrogen atoms have been prepared and characterizated. We have demonstrated an efficient intermolecular arene C-H activation process mediated by Ni(II) complexes of [Ph-PNN]NiEt at elevated temperature. A series of nickel(II) complexes featuring an unsupported, covalently bound p-donor ligand including anilide, phenolate, thiophenolate and tert-butoxide derivatives have been prepared and characterizated. Novel unsymmetric tridentate ligands (H[R-PNO], R = iPr, Ph) have been prepared and characterized. The reaction of [iPr-PNO]NiCl with Na/Hg in thf or ether at room temperature induced C-O bond activation followed by the generation of {[iPr-PNO]Ni}{[iPr-PNO*]NiMe}. 3. Amido Diphosphine Complexes of Cobalt: Syntheses, Structures and Reactivities A series of paramagnetic divalent cobalt complexes ([R-PNP]CoCl, R = iPr, Cy) supported by tridentate diarylamido phosphine ligands have been prepared and characterized. The diamagnetic monovalent cobalt-dinitrogen complexes ([R-PNP]Co(N2), R = iPr, Cy) are accessible from the reaction of [R-PNP]CoCl with LiHBEt3 in THF solution. The dinitrogen complex [Cy-PNP]Co(N2) reacts in THF with terminal alkynes, HC¡ÝCR, yielding vinylidene complexes ([Cy-PNP]Co=C=C(H)(R), R = Ph, SiMe3). The dinitrogen complex [Cy-PNP]Co(N2) and {[iPr-PNP]Co}2(£g-N2) reacts in THF with diphenylacetylene (PhC¡ÝCPh) yielding p complexes ([R-PNP]Co(h2-PhC¡ÝCPh), R = iPr, Cy). 4. Fluorinated Mono- and Diarylamido Complexes of Lithium and Group 4 Metals The synthesis of bis-ligand Group 4 metal complexes ([iPrAr-NF]2MCl2, M= Zr, Hf) are utilizing [iPrAr-NF]Li and MCl4(THF)2. The alkylation of [iPrAr-NF]2MCl2 with RMgCl (R= Me, iBu, PhCH2, Me3SiCH2) produced a series of group 4 metal complexes ([iPrAr-NF]2MR2, M= Zr, Hf) which are catalyst precursors for olefin polymerization. Deprotonation of H[iPr-NF] and H[Cy-NF] with n-BuLi in ethereal solutions at -35 ¢XC produced the lithium complexes {[iPr-NF]Li(solv)}2 (solv = THF, Et2O) and {[Cy-NF]Li(Et2O)}2, respectively. The metathetical reaction of [iPr-NF]Li(Et2O) with 1/3 equiv TiCl4(THF)2 in toluene solution produced the trianilide titanium complex [iPr-NF]3TiCl. A series of novel fluorinated bidentate (H[Mes-NP-RF], R = iPr, Ph) and tridentate ligands (H2[Mes-NPNF]) have been prepared and characterizated.
86

Estudo da modificação ácido-etanólica do amido de mandioca seguida de moagem

Cavallini, Carolina Melki [UNESP] 13 September 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:23:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-09-13Bitstream added on 2014-06-13T20:10:51Z : No. of bitstreams: 1 cavallini_cm_me_sjrp.pdf: 4195835 bytes, checksum: 94483cf0b51a51d605b1bba06617af3f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O tratamento ácido-alcoólico tem sido proposto para modificar a estrutura do grânulo de amido e obter a máxima conversão de amido nativo em amido solúvel. Este amido modificado torna-se frágil quando submetido à moagem em moinho de bola produzindo pequenos cristais que podem ser usados como substitutos de gordura. Neste trabalho, características físico-químicas, estruturais e morfológicas de amidos tratados com ácido-etanol (0,36% HCl em etanol anidro por 1 e 12 h a 30, 40 e 50oC) submetidos ou não a moagem em moinho de bola por 1 h foram analisados e comparados. A recuperação dos amidos foi alta atingindo em média 98%, independente do tempo e temperatura de tratamento. A solubilidade aumentou com o aumento da temperatura e tempo de tratamento e os amidos tratados a 40oC/12h e 50oC/12h tornaram-se totalmente solúveis a 95oC. O tamanho médio dos grânulos de amido de mandioca reduziu com o aumento do tempo e da temperatura de modificação, passando de 25,2 mm para 20,0 mm após 12 h de tratamento a 50oC. A moagem reduziu o tamanho médio dos grânulos de amido nativo e daqueles submetidos a tratamentos ácido-alcoólicos mais brandos (1 h a 30 ou 40oC), enquanto o tamanho médio dos grânulos tratados por 12 h, independente da temperatura, permaneceu inalterado. Os grânulos de amido de mandioca, observados em microscópio eletrônico de varredura, apresentaram forma arredondada e após tratamento com ácido-álcool a 50oC por 12h antes e após moagem, mostraram superfície áspera e rugosa sugerindo erosão com conseqüente solubilização das camadas mais externas dos grânulos. Alguns grânulos mostraramse disformes sugerindo gelatinização parcial que foi mais intensa após moagem. O índice de cristalinidade relativa (IC) dos amidos, determinados por difração de raios- X, aumentou quanto maior o tempo e temperatura de tratamento, enquanto o teor de amilose... / Acid-alcohol treatment has been proposed to modify starch granule structure and obtain maximum conversion of raw starch into soluble starch. Acid-alcohol starch becomes fragile when submitted to the milling in ball mill producing small crystals, which can be used as fat substitute. In this work, physicochemical, structural and morphological characteristics of acid-ethanol cassava starch (0,36% HCl in anhydrous ethanol during 1 and 12 h at 30, 40 e 50oC) followed by milling in ball milling for 1 h were analyzed and compared. The recovery of the modified starches was high reaching 98% independent of time and temperature. The solubility increased with increasing of the treatment temperature and time, and after 1 h at 50ºC the modified starch became totally soluble to 95ºC. The average size of the cassava starch granules decreased with increasing of the treatment time and temperature from 25.2 µm to 20.0 µm after 12 hours of treatment at 50ºC. The milling decreased the average size of the native starch granules and those submitted to milder treatments (1 h at 30 or 40oC), while the average size of the starch granules treated for 12 h, independent of temperature, kept unchanged. From scanning electron microscopy, the native cassava starch granules presented round shape and smooth surface. After acid-ethanol treatment at 50oC for 1h, before and after milling, the granules displayed rough and exfoliated surfaces suggesting erosion with solubilization of the outer layer of the granules. Some granules treated at 50oC during 12 h showed deformed surfaces suggesting partial gelatinization of the starch that was more intense after milling. Relative crystalline index (CI) of the starches, determined from X-ray diffraction, increased with increasing of the treatment time and temperature, while the amylose content, intrinsic viscosity and pasting viscosities decreased... (Complete abstract click electronic access below)
87

Umidade da massa no extrusor sobre os parâmetros de processamento, macroestrutura, cozimento do amido e palatabilidade de alimentos extrusados para gatos. /

Baller, Mayara Aline January 2017 (has links)
Orientador: Aulus Cavalieiri Carciofi / Banca: Jane Maria Bertocco Ezequiel / Banca: Fabiano Cesar Sá / Resumo: A adição de água é uma das variáveis que otimiza o processo de extrusão, uma vez que favorece o umedecimento dos ingredientes e transferência de calor, proporcionando o cozimento adequado; ocasiona mudanças na viscosidade e nas características macroestruturais dos kibbles reduzindo o desgaste da rosca extrusora; e se adicionada em quantidades suficientes, diminui a taxa de ocorrência da reação de Maillard. Apesar de sua importância, não se localizaram estudos sobre os melhores intervalos de umidade de processamento para a produção de rações para gatos. O objetivo deste trabalho foi avaliar os efeitos da umidade da massa no canhão da extrusora sobre os parâmetros de processamento, macroestrutura dos kibbles, balanço de massa e energia, gelatinização do amido e teor de lisina reativa em alimentos extrusados para gatos. Uma fórmula padrão para gatos foi extrusada, e durante o processo de extrusão foram adicionadas seis diferentes quantidades de água no canhão extrusor, correspondendo as umidades da massa de 22%, 27%, 30%, 32%, 35% e 37% (tratamentos). O alimento foi produzido em extrusora de rosca simples e as condições de processamento foram estabilizadas para a dieta 22%, não sendo alteradas para as demais dietas. Os parâmetros registrados foram a temperatura do pré-condicionador, temperatura, pressão e produtividade da extrusora. Amostras de ração foram coletados a cada 15 minutos na saída da extrusora, sendo considerado cada coleta uma unidade experimental. A energia mecânic... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The addition of water is one of the variables that maximizes the extrusion process, since it favors the hydration of the ingredients and the heat transfer, providing a proper cooking; it also causes changes in the viscosity and macrostructural characteristics of the kibbles, reducing the wear of the extruder thread; if added in sufficient amounts it decreases the occurrence of Maillard reaction. Despite their importance, there are no studies evaluating the best processing moisture ranges for the production of cat food. The objective of this work was to evaluate the effects of the in-barrel moisture on the processing parameters, kibble macrostructure, mass and energy balance, starch gelatinization and reactive lysine content of extruded foods for cats. A standard formula for cats was extruded, and during the extrusion process six different amounts of water were added to the extruder barrel, corresponding to the moistures of22%, 27%, 30%, 32%, 35% and 37% (treatments).The feed was extruded in a single screw extruder and the processing conditions were stabilized for the 22% diet, they were not changed for the other diets. The productivity, pressure and temperatures of the conditioner and of the extruder were recorded. Feed samples were collected every 15 minutes at the end of the extruder, each sample was considered an experimental unit. The specific mechanical energy and specific thermal energy transferred to the mass were calculated according to Riaz (2007). The reactive lysin... (Complete abstract click electronic access below) / Mestre
88

Arroz e proteína isolada de soja em dietas pré-iniciais para frangos de corte / Rice and soy protein isolate in pre-starter diets for broilers

Ebling, Patricia Diniz January 2014 (has links)
Apesar da maioria das agroindústrias adotarem dieta específica para a fase pré-inicial, os ingredientes utilizados são os mesmos das fases posteriores, basicamente milho e farelo de soja, os quais nesta fase não apresentam alta digestibilidade. Com base nesse cenário, foram conduzidos três experimentos (Exp) para avaliar a substituição do milho por arroz, branco (AB) ou parboilizado (AP), e a inclusão de 6% de proteína isolada de soja (PIS), visando o uso desses ingredientes em dietas pré-iniciais. No Exp I as substituições foram feitas até 21 dias, enquanto nos Exp II e III, as dietas substitutivas foram utilizadas somente até os sete dias de idade, sendo que nas fases posteriores, todas as aves receberam a mesma ração, com base no milho e no farelo de soja. No Exp I avaliou-se os coeficientes de retenção aparente (CRA) das dietas pré-iniciais e iniciais, digestibilidades ileal e jejunal do amido das dietas iniciais, com intuito de investigar a velocidade de digestão do amido dos diferentes cereais e sua influência no desempenho de frangos de corte (1-21 dias). Na sequência, dois Exp foram conduzidos para avaliar as mesmas dietas pré-iniciais, porém sob a forma física peletizada (Exp II) e farelada (Exp III), variando na porcentagem de óleo (Exp II) ou não (Exp III) no desempenho de frangos (1-33 dias). Não houve interação entre os fatores avaliados (P>0,05). O arroz (AB ou AP), comparado ao milho, conferiu os melhores resultados tanto para os CRA dos componentes das dietas e digestibilidades jejunal e ileal do amido, quanto para desempenho (P<0,01). A diferença entre a digestibilidade ileal e jejunal do amido foi de 11,2 pontos percentuais para o milho, 7,5 para o AB e 4,4 para o AP, mostrando maior velocidade na digestão do amido do arroz comparado ao milho. Entre os dois tipos de arroz, dietas com AB resultaram no maior aproveitamento de todos os componentes das dietas (P<0,05), com exceção do amido e energia metabolizável aparente que não diferiram das dietas com AP (P>0,05). No Exp I, dietas com 6% de PIS apresentaram melhor CRA, porém reduziram o consumo de ração, prejudicando o desempenho das aves (P<0,01). No Exp III, a melhor conversão alimentar conferida pelas dietas com arroz persistiu nas fases posteriores (P<0,05). Nos Exp II e III a inclusão de PIS não melhorou o desempenho das aves (P>0,05). O arroz (AB ou AP) comparado ao milho foi a melhor opção em dietas pré-iniciais. A inclusão de PIS não melhorou o desempenho, em dietas peletizadas ou com igual porcentagem de óleo. Sugere-se a substituição do milho por arroz em dietas pré-iniciais para frangos. / Although most industries use a specific diet for the pre-starter phase, ingredients are used as the later phases, primarily corn and soybean meal, which at this stage does not have high digestibility. Based on this scenario, three experiments (Exp) were conducted to evaluate the replacement of corn by rice, white (WR) or parboiled (PR), and the inclusion of 6% of soy protein isolate (SPI) were conducted aiming to use these ingredients in pre-starter diets. In Exp I substitutions were made up to 21 days. In Exp II and III, substitute diets were used only until seven days of age, whereas in the later stages, all birds received the same diet based on corn and soybean meal. In Exp I we evaluated the coefficients of total tract apparent retention (CTTAR) of pre-starter and starter diets and jejunal and ileal digestibility of starch starter diets, in order to investigate the rate of starch digestion and its influence on broilers performance (1-21 days). In the sequence, two Exp were conducted to evaluate the same pre-starter diet, but in pellets physical form (Exp II) or mash (Exp III) varying the percentage of oil (Exp II) or not (Exp III) and broilers performance until 33 days. There was no interaction between the factors evaluated (P>0.05). Rice (WR or PR) compared to corn, gave the best results for CTTAR of diet components, jejunal and ileal digestibility of starch, and performance (P<0.01). The difference between starch jejunal and ileal digestibility was 11.2 percentage points for corn, 7.5 for WR and 4.4 for PR, showing greater speed in digestion of starch in rice compared to corn. Between the two types of rice, WR diets resulted in greater utilization of all components of the diets (P<0.05), except starch and apparent metabolizable energy that no differed to PR (P>0.05). In Exp I, diets with 6% SPI showed better CTTAR, but reduced feed intake, impairing the performance of broilers (P<0.01). In Exp III, better feed conversion of rice diets was kept in the later stages (P<0.05). In Exp II and III SPI did not improve bird performance (P>0.05). Rice (WR or PR) compared to corn was the best option in pre-starter diets. The inclusion of SPI has not improved the performance in pelleted or equal percentage of oil diets. We suggest the replacement of corn by rice in pre-starter diets for broilers.
89

Efeito de níveis de amido cru e cozido sobre a digestibilidade do próprio amido, da proteína bruta e da matéria seca em dietas práticas para o pacu (Piaractus mesopotamicus Holmberg, 1887)

Rosa, Maria do Carmo Gominho January 2000 (has links)
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias. Curso de Pós-Graduação em Aquicultura / Made available in DSpace on 2012-10-17T12:03:23Z (GMT). No. of bitstreams: 0 / Foi estimada a digestibilidade aparente da proteína bruta, da matéria seca e do amido em dietas práticas, para o pacu (Piaractus mesopotamicus), contendo 20 ou 40% de amido cru ou cozido. Foram utilizados 49 peixes, com peso médio de 219±31g, distribuídos em 4 tanques. Os coeficientes de digestibilidade foram obtidos mediante método indireto, com o óxido crômico a 0,5% como indicador, utilizando tanques cilindro-cônicos em sistema fechado com filtro biológico. As fezes foram coletadas pelo método de decantação. Os tratamentos amido cru/cozido e nível de amido na dieta foram combinados em modelo fatorial e verificados mediante análise de variância ao nível de 5% de significância. A digestibilidade da proteína foi maior para o amido cru e maior para o nível de 40% de amido. Os resultados indicam que o tratamento do amido pelo calor exerceu efeito negativo na digestibilidade da proteína e do amido da dieta e o aumento dos níveis de amido na dieta influenciou positivamente a digestibilidade da matéria seca e do amido.
90

Avaliação da produção enzimática de beta e gama-ciclodextrina em diferentes composições dos substratos dextrina, maltodextrina e fécula de mandioca

Schipmann, Marcos André 25 October 2012 (has links)
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Química, Florianópolis, 2010 / Made available in DSpace on 2012-10-25T14:40:58Z (GMT). No. of bitstreams: 0 / Este trabalho foi realizado com o objetivo de contribuir para o estudo da produção de ciclodextrinas (CDs). A influência da mistura de substratos na composição do meio reacional foi testada para a produção de hetaciclodextrina e gama-ciclodextrina. Ciclomaltodextrinas, mais comumente conhecidas como ciclodextrinas, são oligossacarídeos cíclicos que são produzidas pela ação da enzima ciclodextrina glicosiltransferase (CGTase - cyclomaltodextrin glucanotransferase, EC 2.4.1.19) sobre o amido liquefeito. Ciclodextrinas são compostos muito úteis para a indústria de alimentos, cosmética, farmacêutica e de plásticos, pois possuem uma cavidade apolar, o que favorece o encapsulamento de uma grande variedade de moléculas orgânicas, conferindo-lhes melhores propriedades físico-químicas, tais como maior resistência química a fatores ambientais, maior solubilidade e redução da volatilidade de alguns compostos. Neste trabalho, um preparado líquido de CGTase de Thermoanaerobacter sp. foi utilizado para produzir ciclodextrinas nas seguintes condições: temperatura de 85 °C; tempo de reação de 4h, concentração de substrato de 10g/L; pH = 6,0 e 10 composições contendo os seguintes substratos: amido, maltodextrina e dextrina. Nestas condições, a produção máxima de ciclodextrinas foi obtida no meio contendo 5 g/L de fécula de mandioca e 5 g/L de dextrina como substrato. Os testes mostraram que quantidades superiores a 50% de amido na composição do substrato foram os que apresentaram as melhores quantidades de beta-CD e gama-CD produzidas. No entanto, a composição do teste 5 contendo 50% de amido e 50% de dextrina (5 g/L de amido de mandioca e 5 g/L dextrina) foi a que conduziu à produção mais rápida e em maior concentração das ciclodextrinas. Os testes cujas composições continham quantidades significativas de maltodextrina e dextrina apresentaram uma baixa produção de ciclodextrinas. Neste estudo verificou-se que além dos produtos beta-CD e gama-CD causarem inibição da CGTase de Thermoanaerobacter sp., alguns sacarídeos de baixa massa molecular tais como a maltodextrina e dextrina também têm um efeito inibitório na CGTase. Assim, sugere-se que para a produção de CDs com hidrolisados enzimáticos utilizem-se apenas amidos com baixo grau de dextrose equivalente (DE). / This work has been carried out in order to contribute to the study of the production of cyclodextrins (CDs). The influence of mixture of substrates in the composition of the reaction medium was tested to produce beta-CD and gama-CD. Cyclomaltodextrins, more commonly known as cyclodextrins are cyclic oligosaccharides that are produced by the action of the CGTase enzyme (cyclomaltodextrin glucanotransferase, EC 2.4.1.19) on liquefied starch. Cyclodextrins are very useful compounds for the food, cosmetic, pharmaceutic, and plastic industries, because they have a nonpolar cavity, which favors the encapsulation of a great variety of organic molecules conferring them improved physicochemical properties, such as greater chemical resistance to environmental factors, higher solubility and reduced volatility. A liquid preparation of CGTase from Thermoanaerobacter sp. were used to produced cyclodextrins at conditions: the temperature was 85°C; reaction time was 4h; concentration of substrate was 10g/L; 10 composition containing the following substrate: starch, maltodextrin and dextrin; and pH = 6,0. Using these conditions, the results were as follows: the maximum production of cyclodextrins was composed from: 5g/L of cassava starch and 5g/L of dextrin like substrate. The tests showed that the amount more than 50% starch in the composition of the substrate were the tests that showed the best amount of beta-CD and gama-CD produced. However, the composition of test 5 (5g/L of cassava starch and 5 g/L Dextrin) with 50% starch and 50% dextrin was the fastest produced cyclodextrins and the larger amounts produced in the final reaction time. The tests whose compositions contained significant amounts of maltodextrin and dextrin was a low production of cyclodextrin. In this study it was found that in addition to the products beta-CD and gama-CD cause inhibition of CGTase from Thermoanaerobacter sp, some saccharides of low molecular weight such as maltodextrin and dextrin also has an inhibitory effect on CGTase. Thus it is suggested that for the production of CDs with enzymatic hydrolysates using only starch with low degree of dextrose equivalent (DE).

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