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Riboflavin is an essential part of the human diet. Although the United States does not have a major problem with a riboflavin deficiency, other regions of the world do. This is especially true for those regions whose main subsistence is rice. To help prevent and control riboflavin deficiencies, many cereal grains are now being fortified with riboflavin. The recommended dietary allowance of riboflavin is 1.1-1.6 mg per day. This value increases slightly for pregnant women, breast feeding women, and athletes. Because riboflavin is an essential part of the diet, it is important to ensure that the minimum requirements for this nutrient are met. By determining the amount of riboflavin in food products, an accurate estimate of daily riboflavin intake can be determined. The AOAC (Association of Official Analytical Chemists) approved microbiological riboflavin assay can be tedious and time consuming. A faster approach to the riboflavin assay would greatly benefit the food industry. By scaling down the assay to microtiter plates both, time and materials can be conserved. Use of microtiter plates would also allow for numerous samples to be assayed simultaneously. The goal for developing the microtiter plate assay is to obtain results more rapidly while maintaining the accuracy and precision of the AOAC ( method 940.33I) tube assay.

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Master of Science / Department of Grain Science and Industry / Rebecca Miller / Sorghum is a vital cereal crop grown in many regions around the world. Tolerance to harsh climates and low moisture conditions are unique traits making sorghum an economical choice in an era of global water scarcity. In recent years, sorghum has gained greater recognition as a gluten-free grain and is a safe alternative for individuals suffering from gluten sensitivities or celiac disease. Still, the lack of gluten proteins does not allow sorghum to form a viscoelastic dough. In this study reducing agents were added to improve functional properties of sorghum kafirins for bread baking. Study objectives were to determine the effect of reducing agents on protein body structure of sorghum kafirins, investigate the influence on the sorghum batter consistency, and evaluate the effects on the physical characteristics of sorghum bread. Protein analysis, accomplished using RP-HPLC, showed reducing agents, L-cysteine and sodium metabisulfite, reduced protein structure; increasing RP-HPLC total peak area up to 747% and 681%, respectively. Batter consistency was obtained using a RVA. Treatments of L-cysteine (2.5% fwb) expressed increased RVA peak viscosity and decreased final viscosity. Samples treated with sodium metabisulfite (500 ppm fwb) had increased peak viscosity, holding strength and final viscosity. Yeast activity of batter treated with ≥3000 ppm (fwb) sodium metabisulfite caused volume loss of 95% yet at 500 ppm (fwb) sodium metabisulfite did not have an effect. Batter with 2.5% (fwb) L-cysteine experienced reduced yeast activity after 20 min. Sorghum bread characteristics were altered. Loaf volume and crumb grain characteristics of bread produced using sodium metabisulfite (500 ppm) were equal to that of the control, while initial texture and staling were improved. The addition of L-cysteine (2.5% fwb) to breads lowered loaf volume but produced softer initial crumb texture and improved in-vitro protein digestibility by 18.8%.

Neste trabalho foram realizadas sínteses do nitrosilo complexo trinuclear de rutênio de fórmula [Ru3O(CH3COO)6(NO)(py)2]PF6 (py = piridina) seguindo duas rotas sintéticas diferentes (convencional (a) e uma nova (b) ) a fim de verificar e comparar a eficiência de ambas. Além disso, foi feito o mapeamento da rota sintética convencional para analisar a melhor forma de conduzi-la em cada etapa para que a síntese fosse bem sucedida. Com isso, foi possível afirmar na rota (a) que é preciso purificar dois precursores: o precursor 1 [Ru3O(CH3COO)6(S)3]+ e 3 [Ru3O(CH3COO)6(CO)(L)2], não sendo necessário a purificação do produto final. As modificações vistas necessárias para a otimização da síntese (a) foram a utilização de uma solução recém preparada de bromo e a substituição do metanol seco no frasco lavador por diclorometano seco. Não se descarta a possibilidade da nova rota sintética (b), somada às modificações apontadas neste trabalho, apresentar bons resultados. As caracterizações foram feitas utilizando técnicas de espectroscopia na região UV-visível, infravermelho e RMN. Os estudos de reatividade mostraram que, para ambos os complexos analisados ([RuIII,III,III3O(CH3COO)6(NO)(py)2]PF6 e [RuIII,III,III3O(CH3COO)6(4-acpy)2(NO)]PF6), sugere-se a formação da espécie [RuIII,III,II3O(CH3COO)6(NO2-)(L)2]- onde L = 4-acpy ou py - sendo esta reação dependente da concentração de íons hidroxila do meio. Estudos da reatividade e redução do [Ru3O(CH3COO)6(NO)(py)2]PF6 com o redutor de interesse biológico ácido ascórbico na presença de íons OH-, permitiram sugerir uma hipótese para o mecanismo de liberação de NO0 com estímulo redox, na ausência de luz. Propõe-se que primeiramente o ligante NO0 coordenado sofra um ataque nucleofílico dos íons hidroxila presentes no meio, concomitante a uma transferência eletrônica intra-molecular que gera a espécie [RuIII,III,II3O(CH3COO)6(NO2-)(py)2]-. Este último é reduzido pelo ácido ascórbico, restaurando o ligante NO0 que, agora coordenado à unidade metálica reduzida [RuIII,III,II3O], finalmente é labilizado, gerando o complexo [Ru3O(CH3COO)6(S)(py)2]0 / In this work, the synthesis of the trinuclear ruthenium complex [Ru3O(CH3COO)6(NO)(py)2]PF6 (py = pyridine) was performed following two different synthetic routes (conventional (a) and a new one (b)) in order to verify and to compare the efficiency of both. In addition, the mapping of the conventional synthetic route was done to analyze the best way to conduct it at each step for the synthesis to be successful. It was possible to state in route (a) that two precursors must be purified: precursor 1 [Ru3O(CH3COO)6(S)3]+ and 3 [Ru3O(CH3COO)6(CO)(L)2], no purification of the final product being necessary. The modifications required for the optimization of synthesis (a) were the use of a freshly prepared solution of bromine and the substitution of the dry methanol in the washing flask by dry dichloromethane. We can not rule out the possibility of the new synthetic route (b), added to the modifications pointed out in this work, to present good results. The characterizations were made using UV-visible, infrared and NMR spectroscopy techniques. Reactivity studies for both complexes analyzed ([RuIII,III,III3O(CH3COO)6(NO)(py)2]PF6 and [RuIII,III,III3O(CH3COO)6(4-acpy)NO)]PF6), suggested the formation of the species [RuIII,III,II3O(CH3COO)6(NO2-)(L)2]- - where L = 4-acpy or py - this reaction being dependent on the concentration of hydroxyl ions in the medium. Studies of the reactivity and reduction of compound [Ru3O(CH3COO)6(NO)(py)2]PF6 with the biological reductant ascorbic acid, in the presence of OH- ions, allowed to suggest a hypothesis for the NO0 release mechanism with redox stimulus, in the absence of light. It is proposed that the coordinated NO0 ligand undergoes a nucleophilic attack of the hydroxyl ions present in the medium, concomitant to an intra-molecular electron transfer that generates the species [RuIII,III,II3O(CH3COO)6(NO2-)(py)2]-. The latter is reduced by ascorbic acid, restoring the ligand NO0 which, now coordinated to the reduced metal unit [RuIII,III,II3O], is finally labilized, generating the complex [Ru3O(CH3COO)6(S)(py)2]0

Neste trabalho foram realizadas sínteses do nitrosilo complexo trinuclear de rutênio de fórmula [Ru3O(CH3COO)6(NO)(py)2]PF6 (py = piridina) seguindo duas rotas sintéticas diferentes (convencional (a) e uma nova (b) ) a fim de verificar e comparar a eficiência de ambas. Além disso, foi feito o mapeamento da rota sintética convencional para analisar a melhor forma de conduzi-la em cada etapa para que a síntese fosse bem sucedida. Com isso, foi possível afirmar na rota (a) que é preciso purificar dois precursores: o precursor 1 [Ru3O(CH3COO)6(S)3]+ e 3 [Ru3O(CH3COO)6(CO)(L)2], não sendo necessário a purificação do produto final. As modificações vistas necessárias para a otimização da síntese (a) foram a utilização de uma solução recém preparada de bromo e a substituição do metanol seco no frasco lavador por diclorometano seco. Não se descarta a possibilidade da nova rota sintética (b), somada às modificações apontadas neste trabalho, apresentar bons resultados. As caracterizações foram feitas utilizando técnicas de espectroscopia na região UV-visível, infravermelho e RMN. Os estudos de reatividade mostraram que, para ambos os complexos analisados ([RuIII,III,III3O(CH3COO)6(NO)(py)2]PF6 e [RuIII,III,III3O(CH3COO)6(4-acpy)2(NO)]PF6), sugere-se a formação da espécie [RuIII,III,II3O(CH3COO)6(NO2-)(L)2]- onde L = 4-acpy ou py - sendo esta reação dependente da concentração de íons hidroxila do meio. Estudos da reatividade e redução do [Ru3O(CH3COO)6(NO)(py)2]PF6 com o redutor de interesse biológico ácido ascórbico na presença de íons OH-, permitiram sugerir uma hipótese para o mecanismo de liberação de NO0 com estímulo redox, na ausência de luz. Propõe-se que primeiramente o ligante NO0 coordenado sofra um ataque nucleofílico dos íons hidroxila presentes no meio, concomitante a uma transferência eletrônica intra-molecular que gera a espécie [RuIII,III,II3O(CH3COO)6(NO2-)(py)2]-. Este último é reduzido pelo ácido ascórbico, restaurando o ligante NO0 que, agora coordenado à unidade metálica reduzida [RuIII,III,II3O], finalmente é labilizado, gerando o complexo [Ru3O(CH3COO)6(S)(py)2]0 / In this work, the synthesis of the trinuclear ruthenium complex [Ru3O(CH3COO)6(NO)(py)2]PF6 (py = pyridine) was performed following two different synthetic routes (conventional (a) and a new one (b)) in order to verify and to compare the efficiency of both. In addition, the mapping of the conventional synthetic route was done to analyze the best way to conduct it at each step for the synthesis to be successful. It was possible to state in route (a) that two precursors must be purified: precursor 1 [Ru3O(CH3COO)6(S)3]+ and 3 [Ru3O(CH3COO)6(CO)(L)2], no purification of the final product being necessary. The modifications required for the optimization of synthesis (a) were the use of a freshly prepared solution of bromine and the substitution of the dry methanol in the washing flask by dry dichloromethane. We can not rule out the possibility of the new synthetic route (b), added to the modifications pointed out in this work, to present good results. The characterizations were made using UV-visible, infrared and NMR spectroscopy techniques. Reactivity studies for both complexes analyzed ([RuIII,III,III3O(CH3COO)6(NO)(py)2]PF6 and [RuIII,III,III3O(CH3COO)6(4-acpy)NO)]PF6), suggested the formation of the species [RuIII,III,II3O(CH3COO)6(NO2-)(L)2]- - where L = 4-acpy or py - this reaction being dependent on the concentration of hydroxyl ions in the medium. Studies of the reactivity and reduction of compound [Ru3O(CH3COO)6(NO)(py)2]PF6 with the biological reductant ascorbic acid, in the presence of OH- ions, allowed to suggest a hypothesis for the NO0 release mechanism with redox stimulus, in the absence of light. It is proposed that the coordinated NO0 ligand undergoes a nucleophilic attack of the hydroxyl ions present in the medium, concomitant to an intra-molecular electron transfer that generates the species [RuIII,III,II3O(CH3COO)6(NO2-)(py)2]-. The latter is reduced by ascorbic acid, restoring the ligand NO0 which, now coordinated to the reduced metal unit [RuIII,III,II3O], is finally labilized, generating the complex [Ru3O(CH3COO)6(S)(py)2]0

Thesis (Ph. D.)--University of Virginia, 2007. / Includes bibliographical references. Also available online through Digital Dissertations.

Orientador: Antonio José Gomez Cobo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-25T04:45:50Z (GMT). No. of bitstreams: 1 Ganzaroli_DaianaRezende_M.pdf: 2594677 bytes, checksum: 083b3d18fb22abe80176433b885c8c2a (MD5) Previous issue date: 2014 / Resumo: A hidrogenação de compostos aromáticos tem sido muito estudada devido à sua ampla gama de aplicações industriais, bem como às restrições ambientais impostas por diversos países. Nesse contexto, o presente trabalho tem o objetivo estudar os efeitos do pH de impregnação e da natureza do agente redutor sobre o desempenho de catalisadores de Ni e Ru suportados em ?-Al2O3, empregados na hidrogenação de tolueno em fase líquida. Para tanto, catalisadores foram preparados a partir de soluções aquosas dos precursores de NiCl3.6H2O e RuCl3.xH2O, através de impregnação úmida conduzida a pH constante entre 4 e 8. Durante a impregnação, catalisadores foram reduzidos a 353 K (80 ºC) em fase líquida, empregando-se formaldeído (H2CO) ou boroidreto de sódio (NaBH4) como agentes redutores. Os catalisadores de Ni e Ru também foram reduzidos sob fluxo de H2 a 773 e 573 K (500 e 300 ºC) respectivamente, após a impregnação úmida. O suporte foi caracterizado utilizando as técnicas de análise granulométrica, adsorção de N2 (método de B.E.T.) e titulação potenciométrica. As técnicas de MEV+EDX e XPS foram empregadas para determinar a composição química dos sólidos empregados, e a formação da fase ativa dos catalisadores foi estudada através de TPR. O desempenho dos catalisadores foi avaliado na reação de hidrogenação do tolueno em fase líquida, conduzida num reator Parr do tipo "slurry" à temperatura de 373 K (100 ºC) e sob pressão de H2 de 5 MPa (50 atm). Os resultados obtidos mostram que os catalisadores de Ru/Al2O3 são muito mais ativos que os catalisadores de Ni/Al2O3, sendo ainda seletivos para a obtenção do produto da hidrogenação parcial do tolueno (metilcicloexeno). A maior atividade dentre os catalisadores de Ni/Al2O3 é obtida para um pH de impregnação acima do ponto isoelétrico (pI) do suporte, igual a 6,2, utilizando-se o agente redutor H2CO. No caso dos catalisadores de Ru/Al2O3, o agente H2CO também leva às maiores atividades catalíticas, tendo-se o valor máximo para o pH igual ao pI do suporte. Já o maior rendimento de metilcicloexeno é obtido para o pH igual a 4. Os comportamentos catalíticos observados são analisados e discutidos à luz dos resultados da caracterização dos sólidos e da literatura técnica especializada / Abstract: The hydrogenation of aromatic compounds has been studied due to the wide range of industrial applications, as well as to environmental restrictions imposed by several countries. In this context, the present work aims to study the effects of the impregnation pH and the nature of the reducing agent on the performance of Ni and Ru catalysts supported on ?-Al2O3, employed for toluene hydrogenation in liquid phase. For this, catalysts were prepared from aqueous solution of NiCl3.6H2O and RuCl3.xH2O precursors by wet impregnation, conduced at constant pH between 4 and 8. During impregnation, catalysts were reduced at 353 K (80 ºC) in liquid phase, using formaldehyde (H2CO) or sodium borohydride (NaBH4) as reducing agents. The Ni and Ru catalysts were also reduced under H2 flow at 773 and 573 K (500 and 300 °C) respectively, after the wet impregnation. The support was characterized using the techniques of particle size, N2 adsorption (B.E.T. method) and potentiometric titration. The techniques of SEM+EDX and XPS were used to determine the chemical composition of the employed solids, and the formation of the catalysts active phase was studied by TPR. The catalysts performance were evaluated for toluene hydrogenation reaction in the liquid phase, carried out in a Parr reactor of the slurry type at the temperature of 373 K (100 ° C) and under H2 pressure of 5 MPa (50 atm). The results show that Ru/Al2O3 catalysts are much more active than the Ni/Al2O3 catalysts, and even selective for obtaining the product of the partial hydrogenation of toluene (methylcyclohexene). The highest activity among the Ni/Al2O3 catalysts is obtained by impregnation at pH above of the isoelectric point (pI) of the support, equal to 6.2, using the reducing agent H2CO. In the case of the Ru/Al2O3 catalysts, the H2CO agent also leads to higher catalytic activities, having a maximum value at pH equal to the support pI. However, the highest yield of methylcyclohexene is obtained at pH 4. The observed catalytic behaviors are analyzed and discussed in the light of the results of the characterization of solids and specialized technical literature / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestra em Engenharia Química