Electron transfer to and between the redox centers of milk xanthine oxidase was investigated by laser flash-photolysis. Evidence is presented for slow equilibration of electrons (k < 38 s⁻¹) between the various redox centers of the enzyme. The enzyme-bound flavin and the heme moieties of the flavoprotein and cytochrome subunits of p-cresol methyl hydroxylase from Pseudomonas putida are both reduced rapidly in a second order manner by 5-dRF generated by the laser flash, followed by slower first order intramolecular electron transfer (k = 220 s⁻¹) from the protein-bound neutral flavin radical to the oxidized cytochrome. Complex formation between spinach ferredoxin:NADP⁺-reductase (FNRₒᵪ), spinach ferredoxin (Fdₒᵪ), rubredoxin (Rdₒᵪ) from Clostridium pasteurianum, two homologous HIPIP's from Ectothiorhodospira halophila (iso-1 and iso-2) and two homologous cytochromes (cytochromes-c₂ from Paracoccus denitrificans and Rhodospirrilum rubrum) have been investigated. Evidence is presented supporting the formation of 1:1 complexes that are stabilized by attractive electrostatic interactions at low ionic strength. Kinetic studies of the above-mentioned complexes provide evidence for extremely rapid to relatively slower intracomplex electron transfer rates (k 7000 s⁻¹ to 4 s⁻¹). In addition the effect of complexation on the degree of accessibility of the various redox centers of the respective complexes to reduction by small reductants such as 5-dRF· and LfH· generated by the laser flash has been evaluated. The effect of both pH and ionic strength on the second order rate of reduction and the intracomplex rates in the respective complexes have also been investigated. The results have been interpreted in terms of redox potential differences, electrostatic and structural features that influence the electron transfer rates in these systems.

The Effect of Sulindac was studied on an animal model of ischemic stroke. Sulindac, a non steroid anti inflammatory drug (NSAID) could protect cell death due to hypoxia/reoxygenation. This drug was given 2 days before and 24 hrs after ischemia until animals were sacrificed on 3rd or 11th day. Infarct size was measured for these animals. Sulindac induced Hsp 27 in ischemic penumbra and core on Day 3 & 11 with uncoated nylon suture which shows its cell-survival and anti-apoptotic activity. Also, it increased expression of cell survival markers such as Akt, Bcl2 & Grp 78 in ischemic penumbra and core. With silicon suture it reduced expression of Hsp 27 in ischemic penumbra and core, alleviating cell stress and having pro-survival and anti-stress effects. In conclusion sulindac may have excellent potential as neuro protective agent against oxidative stress in cerebral ischemia. / by JIgar Modi. / Thesis (M.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

The enzyme Methionine sulfoxide reductase A (MsrA) repairs oxidized proteins, and may act as a scavenger of reactive oxygen species (ROS), making it a potential therapeutic target for age-related neurodegenerative diseases. The anoxia-tolerant turtle offers a unique model to observe the effects of oxidative stress on a system that maintains neuronal function following anoxia and reoxygenation, and that ages without senescence. MsrA is present in both the mitochondria and cytosol, with protein levels increasing respectively 3- and 4-fold over 4 hours of anoxia, and remaining 2-fold higher than basal upon reoxygenation. MsrA was knocked down in neuronally-enriched cell cultures via RNAi transfection. Propidium iodide staining showed no significant cell death during anoxia, but this increased 7-fold upon reoxygenation, suggesting a role for MsrA in ROS suppression during reperfusion. This is the first report in any system of MsrA transcript and protein levels being regulated by oxygen levels. / by Lynsey Erin Bruce. / Thesis (M.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

O processo de clarificação do caldo de cana-de-açúcar tem sido alvo de vários trabalhos de pesquisa, no intuito de melhorar a qualidade do açúcar obtido, tanto do ponto de vista de novas tecnologias em equipamentos e processos, quanto a respeito do estudo das propriedades físico-químicas da sacarose durante sua decomposição na clarificação. Os POA (Processos Oxidativos Avançados) têm sido aplicados, em especial, ozonização do caldo, tal qual este projeto propõe estudar uma alternativa ao processo convencional de sulfitação do caldo para a obtenção do açúcar cristal branco, através da utilização do peróxido de hidrogênio como agente de redução de cor ICUMSA do caldo e o impacto na degradação da sacarose em compostos não-cristalizáveis, reduzindo o rendimento industrial. Não há relatos na literatura sobre condições ideais de uso do peróxido de hidrogênio, bem como quais alterações essa tecnologia pode ocasionar no caldo. Por isso, buscaram-se elucidar quais são as melhores condições de trabalho e quais fatores influenciam na sua ação, bem como quais são os seus efeitos sobre o caldo tratado. As melhores condições para o uso do peróxido de hidrogênio são: pH entre 3,0 e 7,0, temperatura entre 40 a 70ºC, peróxido de hidrogênio maior que 600 ppm e dextrana menor que 750 ppm. Pode-se verificar que a maturidade da cana-de-açúcar no corte pode influenciar na ação do peróxido de hidrogênio, uma vez que quanto maior o grau de maturação da cana-de-açúcar, maior quantidade de compostos fenólicos e maior a cor inicial do caldo. A cinética de degradação da cor ICUMSA não apresentou distribuição regular, oscilando em pequenos intervalos de tempo, devido provavelmente à pequena quantidade de peróxido de hidrogênio utilizada nos ensaios. Não houve diminuição visual da cor do caldo quando utilizado doses até 5.000 ppm de H2O2. Com relação à turbidez, não foi possível identificar a influência da peroxidação nos valores. Houve degradação de sacarose quando foi feito o tratamento combinando temperatura elevada (62ºC) com pH ácido (3,8). A rede neural artificial (RNA) mostrou um bom ajuste na maioria dos casos apresentados e indicou a variável temperatura como a que apresentou maior influência na diminuição da absorbância à 420 nm. A segunda variável com maior influência foi o Brix do caldo de cana-de-açúcar. A espectrometria de massa mostrou que a peroxidação, nas condições reacionais avaliadas, não foi capaz de reduzir significativamente a cor do caldo, sugerindo que haja uma promoção de sedimentação de algumas impurezas do caldo, o que faz com que haja uma diminuição visual da cor do mesmo, não ocorrendo aparentemente reação química no caldo, quando utilizamos doses de 50.000 ppm. Assim o peróxido de hidrogênio não funcionou como um agente clarificante, nas condições estudadas. / The process of sugarcane juice clarification has been the subject of several research papers in order to improve the quality of sugar obtained both from the point of view of new technologies in equipment and processes , as concerning the study of physico- chemical properties of sucrose during decomposition in clarification . The AOP \'s (Advanced Oxidation Process ) have been applied in particular ozonation of the juice as such this design proposed to study an alternative to conventional process sulphiting of the juice to obtain sugar white crystal through the use of hydrogen peroxide as reduction ICUMSA color of juice and the impact on the degradation of sucrose into non- crystallizable compounds by reducing industrial productivity agent. There are no reports in the literature on optimal conditions of use of hydrogen peroxide as well as the technology changes which may result in the juice. Therefore , we sought to elucidate what are the best working conditions and factors which influence in its action, and what are its effects on the treated juice. The best conditions for the use of hydrogen peroxide are: pH lower than 7.0 or higher than 3.0, temperature greater than 40 °C and below 70 °C, hydrogen peroxide greater than 600 ppm and lower than 750 ppm dextran. We observed that the maturity of the sugarcane cutting can influence the action of hydrogen peroxide, since the more mature sugarcane, a greater number of phenolic compounds are produced and the higher the initial color of the juice. The kinetics of ICUMSA color degradation showed no regular distribution, oscillating at short time intervals, probably due to the small amount of hydrogen peroxide used in the tests. There was no visual color decrease of the juice. Regarding turbidity, it was not possible to identify the influence of peroxidation values . There was sucrose degradation when the treatment was made by combining high temperature (62°C) at acid pH (3.8). The artificial neural network (ANN) showed a good fit in most cases presented and indicated the variable temperature with the highest influence on the absorbance decrease at 420 nm. The second variable with the greatest influence was the Brix of sugarcane juice. Mass spectrometry showed that peroxidation in the reaction conditions evaluated was not able to significantly reduce the sugarcane juice color, suggesting a promotion of sedimentation of some impurities in the juice, hindering a reduction of its visual color, and apparently, there was no chemical reaction in the juice, using rate of hydrogen peroxide of 50,000 ppm. Thus hydrogen peroxide did not work as a clarifying agent, in the studied conditions

Ischemic stroke has a multiplicity of pathophysiological mechanisms. Granulocyte-colony stimulating factor (G-CSF) is an endogenous growth factor that exerts a diverse range of neuroprotection against ischemic stroke. Several lines of evidence demonstrated the contribution of endoplasmic reticulum (ER) in apoptotic cell death involving ischemia. Cell culture of undifferentiated PC12 cells were subjected to 10mM glutamate and selected doses of G-CSF (25ng/ml, 50ng/ml, 100ng/ml and 250ng/ml) for 24 hours. Cell viability, expression of the G-CSF receptor and expression level of CHOP were assessed in vitro. Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO). Rats were subcutaneously injected with G-CSF (n= 15; 50ug/kg body weight) 24 hours post-MCAO for 4 days. Vehicle treated rats were administered 5% dextrose for 1 day (n=4) or 4 days (n=16). Sham-operated rats (n=9) were not subjected to MCAO. Neurological deficit and infarct volume were measured while expression levels of pAKT, Bcl2, Bax, Bak, cleaved caspase-3, GRP78, ATF4, ATF6, p-p38MAPK, pJNK, CHOP and HSP27 were analyzed by western blotting. In vitro G-CSF receptor was expressed on undifferentiated PC12 cell, and an optimal dose of 50 ng/ml G-CSF significantly protected these cells against glutamate-induced cytotoxicity (P < 0.05). G-CSF significantly down-regulated (P < 0.01) the ER stressinduced pro-apoptotic marker CHOP in vitro. In vivo, G-CSF reduced infarct volume to 50% while significantly improved neurological deficit compared to vehicle rats. G-CSF significantly (P < 0.05) up-regulated pro-survival proteins pAKT and Bcl2 while downregulating pro-apoptotic proteins Bax, Bak and cleaved caspase 3 in the ischemic brain. It also significantly (P < 0.05) downregulated the ER intraluminal stress sensor GRP78, proteins of ER stress induced intracellular pathway; ATF4, ATF6, p-p38MAPK, pJNK and the ER stress induced apoptotic marker CHOP, which suggests that ER stress is being ameliorated by G-CSF treatment. G-CSF also reduced the level of HSP27, providing additional evidence of cellular stress reduction. G-CSF treatment increased cell survival by attenuating both general pro-apoptotic proteins and specific effector proteins in the ER stress induced apoptotic pathways. Our data has provided new insight into the anti-apoptotic mechanism of G-CSF, especially as it relates to ER stress induced apoptosis in ischemia. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

The methionine sulfoxide reductase (Msr) enzymes catalyze the reduction of methionine sulfoxide (Met(O)) to methionine. The Msr enzymes protect cells against oxidative stress and may have a role in aging. The MsrA family of enzymes reduces stereospecifically the S epimer of free and protein-bound Met(O) while the MsrB family reduces the R epimer of Met(O) in proteins. It has been generally accepted, primarily from studies on MsrA, that the biological reductant for the Msr enzymes is thioredoxin (Trx), although high levels of dithiothreitol (DTT) can be used as the reductant in vitro. In contrast, certain MsrB enzymes show less than 10% of the activity with Trx as compared to DTT. This raises the possibility that in animal cells Trx may not be the direct hydrogen donor for the MsrB enzymes. Studies with bovine liver extracts have shown that thionein, the apoprotein of metallothionein, can function as a reductant for the Msr proteins. Certain selenium compounds such as selenocystamine and selenocystine can also serve as potent reducing agents for the Msr enzymes. Since an increased activity of Msr enzymes can reduce the level of oxidative damage in tissues, compounds that could activate Msr may have therapeutic potential. A high-throughput screening assay has been developed to screen large chemical libraries to find activators of MsrA, as well as specific inhibitors that could be useful research tools. This study will be done in collaboration with The Scripps Florida Research Institute. Sulindac was originally developed as a non-steroidal anti-inflammatory drug but has also shown efficacy in the treatment of certain cancers. The S epimer of sulindac is known to be reduced by MsrA, but the enzymes responsible for reduction of the R epimer are not known. / An activity has been purified from rat liver which is capable of reducing the R epimers of sulindac, free Met(O) and a dabsylated Met(O) substrate, the latter suggesting that this enzyme may have properties similar t o the MsrB enzymes. The oxidation of the epimers of sulindac to sulindac sulfone has also been characterized, and the members of the cytochrome P450 family involved in the oxidation have been identified. / by David J. Brunell. / Thesis (Ph.D.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

Copper hydrides such as [Ph₃PCuH]₆ (Stryker’s Reagent) are textbook reagents in organic chemistry for the selective hydrogenation of α,β-unsaturated carbonyl compounds. Despite their widespread use both stoichiometrically and catalytically, there are many important questions about polynuclear copper hydrides that have not been answered. I have investigated the electron transfer chemistry of [Ph₃PCuH]₆ and related copper hydrides. Copper hydrides (E₁/₂ = –1.0 to –1.2 V vs FcH/FcH⁺) are good one-electron reducing agents. Stopped-flow techniques have allowed the detection of electron transfer intermediates in copper hydride reactions. The fate of the copper containing products after electron transfer or hydride transfer reactions has been investigated. An unusual cationic copper hydride, [(Ph₃P)₇Cu₇H₆]⁺ was found to be the major product of these reactions. Methods of converting this species back to [Ph₃PCuH]₆ have been investigated. The chemistry of this cationic species plays an important role in catalytic use of copper hydrides.

Lam Chun Pong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references. / Abstracts in English and Chinese. / Table of Contents --- p.i / Acknowledgements --- p.v / Abstracts --- p.vi / Abbreviations --- p.viii / Chapter CHAPTER 1. --- SYNTHESIS AND REACTIVITY STUDIES OF MODEL COMPLEXES FOR INTRADIOL DIOXYGENASES WITH BENZIMIDAZOLE- CONTAINING LIGAND / Chapter I.1 --- Introduction / Chapter I.1.1 --- General Background --- p.1 / Chapter I.1.2 --- A General Review on the Modeling Chemistry for Catechol Dioxygenases --- p.3 / Chapter I.1.3 --- Intradiol Dioxygenases --- p.3 / Chapter I.1.3.1 --- Early model studies for intradiol dioxygenases --- p.5 / Chapter I.1.3.2 --- Factors affecting enzymatic reactivity for intradiol dioxygenases --- p.6 / Chapter I.1.3.3 --- Other functional models for intradiol dioxygenases --- p.7 / Chapter I.1.3.4 --- Reactivity studies of model complexes --- p.8 / Chapter I.1.4 --- Extradiol Dioxygenases --- p.8 / Chapter I.1.4.1 --- Early model studies for extradiol dioxygenases --- p.11 / Chapter I.1.4.2 --- Iron(III) complexes with extradiol properties --- p.12 / Chapter I.1.5 --- Objective of This Work --- p.14 / Chapter I.2 --- Results and Discussion / Chapter I.2.1 --- Synthesis of the Ligand Ntb --- p.15 / Chapter I.2.2 --- Synthesis of the Model Complex [Fe(ntb)Cl2]Cl --- p.16 / Chapter I.2.3 --- Synthesis of Enzyme-Substrate Model Complexes --- p.16 / Chapter I.2.4 --- Oxygenation Reactivities of Enzyme-Substrate Model Complexes 2-4 --- p.18 / Chapter I.2.4.1 --- Oxygenation of [Fe(ntb)(dbc)](C104) (2) in DMF --- p.18 / Chapter I.2.4.2 --- Oxygenation of [Fe(ntb)(cat)](Cl04) (3) in DMF --- p.21 / Chapter I.2.4.3 --- Oxygenation of [Fe(ntb)(tcc)](ClO4) (4) in DMF --- p.23 / Chapter I.2.4.4 --- Comparison of the oxygenation reactivities of complexes2-4 --- p.25 / Chapter I.2.5 --- Identification of Oxidative Cleavage Products --- p.27 / Chapter I.2.5.1 --- Isolation of oxidative cleavage products of complex 2 --- p.27 / Chapter I.2.5.2 --- Identification of cleavage products --- p.27 / Chapter I.2.6 --- Physical Characterization of Complexes 1-4 --- p.29 / Chapter I.2.6.1 --- Melting-points --- p.29 / Chapter I.2.6.2 --- Cyclic Voltammograms --- p.30 / Chapter I.2.6.3 --- EPR spectra --- p.31 / Chapter I.2.7 --- Molecular Structures of Complexes 1-4 --- p.34 / Chapter I.2.7.1 --- Molecular structure of [Fe(ntb)Cl2]Cl-4H20 (1) --- p.34 / Chapter I.2.7.2 --- Molecular structure of [Fe(ntb)(dbc)](Cl04)-2Me0H-H20 (2) --- p.36 / Chapter I.2.7.3 --- Molecular structure of [Fe(ntb)(cat)](ClO4) H20 (3) --- p.38 / Chapter I.2.7.4 --- Molecular structure of [Fe(ntb)(tcc)](Cl04).Me2C(0).H20 (4) --- p.41 / Chapter I.2.7.5 --- Comparison of the molecular structures of complexes 1-4 --- p.43 / Chapter I.3 --- Experimentals for Chapter 1 --- p.45 / Chapter I.4 --- References for Chapter 1 --- p.49 / Chapter CHAPTER II --- iron(iii) complexes containing N202 and N3O type ligands as models for INTRADIOL DIOXYGENASES / Chapter II.1 --- Introduction / Chapter II.1.1 --- Brief Remarks on Model Studies of Intradiol Dioxygenases. --- p.53 / Chapter II.1.2 --- Objective of This Work --- p.53 / Chapter II.2 --- Results and Discussion / Chapter II.2.1 --- Synthesis of N202 and N30 Type Ligands --- p.55 / Chapter II.2.2 --- Synthesis of Model Complexes --- p.57 / Chapter II.2.2.1 --- Model complex with ligand L1H --- p.57 / Chapter II.2.2.2 --- Model complex with ligand L2H2 --- p.58 / Chapter II.2.3 --- Synthesis of Enzyme-Substrate Model Complexes --- p.59 / Chapter II.2.3.1 --- Synthesis of enzyme-substrate model complexes from 14.… --- p.59 / Chapter II.2.3.2 --- Attempted synthesis of enzyme-substrate model complexes starting from 15 --- p.61 / Chapter II.2.4 --- Reaction of Complex 16 with Dioxygen --- p.61 / Chapter II.2.4.1 --- Oxygenation of [Fe(L1)(dbc)] (16) in DMF --- p.65 / Chapter II.2.5 --- Identification of Oxidative Cleavage Products --- p.64 / Chapter II.2.5.1 --- Isolation of oxidative cleavage products of complex 16 --- p.64 / Chapter II.2.5.2 --- Identification of cleavage products --- p.65 / Chapter II.2.6 --- "Physical Characterization of L1H, L2H2, Complexes 14-18" --- p.66 / Chapter II.2.6.1 --- NMR spectra --- p.67 / Chapter II.2.6.2 --- Melting-points --- p.69 / Chapter II.2.6.3 --- Mass spectra --- p.69 / Chapter II.2.6.4 --- Cyclic voltammogram --- p.69 / Chapter II.2.6.4 --- EPR spectra --- p.70 / Chapter II.2.7 --- "Molecular Structures of Complexes 14,15 and 18" --- p.71 / Chapter II.2.7.1 --- Molecular structure of [Fe(L1)(MeOH)Cl][BPh4].MeOH (14) --- p.72 / Chapter II.2.7.2 --- Molecular structure of [Fe(L2)Cl].MeOH (15) --- p.75 / Chapter II.2.7.3 --- Molecular structure of [Et3 Nh]3［Fe(tcc)3］.H2O(18) --- p.78 / Chapter II.3 --- Experimentals for Chapter 2 --- p.80 / Chapter II.4 --- References for Chapter 2 --- p.87 / APPENDIX 1 General Procedures and Physical Measurements --- p.89 / "APPENDIX 2 Selected Crystallographic Data for Complexes 1-4, 15,16 and 18.…" --- p.90 / Table A-l.Selected crystallographic data for complexes 1-4 --- p.91 / "Table A-2.Selected crystallographic data for complexes 15, 16 and 18" --- p.92 / "APPENDIX 3 Other Physical Data for Ligand L1H L2H2, Complexes 2 and 16" --- p.93 / Figure A-l.1H NMR spectrum of ligand L1H --- p.94 / Figure A-2.13C NMR spectrum of ligand L1H --- p.94 / Figure A-3.1H NMR spectrum of ligand L2H2 --- p.95 / Figure A-4.13C NMR spectrum of ligand L2H2 --- p.95 / Figure A-5.GC spectrum of the oxidative cleavage products of complex 2 --- p.96 / Figure A-6.- A-l 1.Mass spectra of the oxidative cleavage products of Complex 2 --- p.96 / Figure A-12.GC spectrum of the oxidative cleavage products of complex 16 --- p.99 / Figure A-13.- A-23.Mass spectra of the oxidative cleavage products of Complex 16 --- p.99 / Figure A-24.GC spectrum of dbcH2 standard --- p.105 / Figure A-25.Mass spectrum of dbcH2 standard --- p.106 / Figure A-26.GC spectrum of dbcq standard --- p.106 / Figure A-27.Mass spectrum of dbcq standard --- p.107

O processo de clarificação do caldo de cana-de-açúcar tem sido alvo de vários trabalhos de pesquisa, no intuito de melhorar a qualidade do açúcar obtido, tanto do ponto de vista de novas tecnologias em equipamentos e processos, quanto a respeito do estudo das propriedades físico-químicas da sacarose durante sua decomposição na clarificação. Os POA (Processos Oxidativos Avançados) têm sido aplicados, em especial, ozonização do caldo, tal qual este projeto propõe estudar uma alternativa ao processo convencional de sulfitação do caldo para a obtenção do açúcar cristal branco, através da utilização do peróxido de hidrogênio como agente de redução de cor ICUMSA do caldo e o impacto na degradação da sacarose em compostos não-cristalizáveis, reduzindo o rendimento industrial. Não há relatos na literatura sobre condições ideais de uso do peróxido de hidrogênio, bem como quais alterações essa tecnologia pode ocasionar no caldo. Por isso, buscaram-se elucidar quais são as melhores condições de trabalho e quais fatores influenciam na sua ação, bem como quais são os seus efeitos sobre o caldo tratado. As melhores condições para o uso do peróxido de hidrogênio são: pH entre 3,0 e 7,0, temperatura entre 40 a 70ºC, peróxido de hidrogênio maior que 600 ppm e dextrana menor que 750 ppm. Pode-se verificar que a maturidade da cana-de-açúcar no corte pode influenciar na ação do peróxido de hidrogênio, uma vez que quanto maior o grau de maturação da cana-de-açúcar, maior quantidade de compostos fenólicos e maior a cor inicial do caldo. A cinética de degradação da cor ICUMSA não apresentou distribuição regular, oscilando em pequenos intervalos de tempo, devido provavelmente à pequena quantidade de peróxido de hidrogênio utilizada nos ensaios. Não houve diminuição visual da cor do caldo quando utilizado doses até 5.000 ppm de H2O2. Com relação à turbidez, não foi possível identificar a influência da peroxidação nos valores. Houve degradação de sacarose quando foi feito o tratamento combinando temperatura elevada (62ºC) com pH ácido (3,8). A rede neural artificial (RNA) mostrou um bom ajuste na maioria dos casos apresentados e indicou a variável temperatura como a que apresentou maior influência na diminuição da absorbância à 420 nm. A segunda variável com maior influência foi o Brix do caldo de cana-de-açúcar. A espectrometria de massa mostrou que a peroxidação, nas condições reacionais avaliadas, não foi capaz de reduzir significativamente a cor do caldo, sugerindo que haja uma promoção de sedimentação de algumas impurezas do caldo, o que faz com que haja uma diminuição visual da cor do mesmo, não ocorrendo aparentemente reação química no caldo, quando utilizamos doses de 50.000 ppm. Assim o peróxido de hidrogênio não funcionou como um agente clarificante, nas condições estudadas. / The process of sugarcane juice clarification has been the subject of several research papers in order to improve the quality of sugar obtained both from the point of view of new technologies in equipment and processes , as concerning the study of physico- chemical properties of sucrose during decomposition in clarification . The AOP \'s (Advanced Oxidation Process ) have been applied in particular ozonation of the juice as such this design proposed to study an alternative to conventional process sulphiting of the juice to obtain sugar white crystal through the use of hydrogen peroxide as reduction ICUMSA color of juice and the impact on the degradation of sucrose into non- crystallizable compounds by reducing industrial productivity agent. There are no reports in the literature on optimal conditions of use of hydrogen peroxide as well as the technology changes which may result in the juice. Therefore , we sought to elucidate what are the best working conditions and factors which influence in its action, and what are its effects on the treated juice. The best conditions for the use of hydrogen peroxide are: pH lower than 7.0 or higher than 3.0, temperature greater than 40 °C and below 70 °C, hydrogen peroxide greater than 600 ppm and lower than 750 ppm dextran. We observed that the maturity of the sugarcane cutting can influence the action of hydrogen peroxide, since the more mature sugarcane, a greater number of phenolic compounds are produced and the higher the initial color of the juice. The kinetics of ICUMSA color degradation showed no regular distribution, oscillating at short time intervals, probably due to the small amount of hydrogen peroxide used in the tests. There was no visual color decrease of the juice. Regarding turbidity, it was not possible to identify the influence of peroxidation values . There was sucrose degradation when the treatment was made by combining high temperature (62°C) at acid pH (3.8). The artificial neural network (ANN) showed a good fit in most cases presented and indicated the variable temperature with the highest influence on the absorbance decrease at 420 nm. The second variable with the greatest influence was the Brix of sugarcane juice. Mass spectrometry showed that peroxidation in the reaction conditions evaluated was not able to significantly reduce the sugarcane juice color, suggesting a promotion of sedimentation of some impurities in the juice, hindering a reduction of its visual color, and apparently, there was no chemical reaction in the juice, using rate of hydrogen peroxide of 50,000 ppm. Thus hydrogen peroxide did not work as a clarifying agent, in the studied conditions

A pink color defect is commonly observed in freshly cut surfaces of cooked turkey rolls and fades rapidly upon exposure to air. The non uniform pink color makes the product appear undercooked, and the product must be discounted. The oxidation-reduction potential of the meat is important in development of pink defect. A pink color similar to that of commercial product was observed when the cooked meat was treated with either sodium nitrite or sodium dithionite. The pink color in nitrite treated meat was due to nitroso pigment formation, but in samples treated with dithionite the pink color was due to formation of a hemochrome complex. Pink color was also observed in turkey rolls formulated with nicotinic acid, nicotinamide or sodium nitrite. Reflectance and absorbance spectrophotometric studies on commercial or laboratory prepared samples having pink defect showed that the responsible pigment was a reduced hemochrome rather than a nitroso pigment. The hemochrome is probably a nicotinamide-denatured globin complex with ferrous iron of the heme molecule. Oxidation-reduction potential measurement of meat systems showed that hemochrome formation is promoted by reducing conditions and prevented by oxidizing conditions. All constituents necessary for formation of pink defect are present in turkey meat, the variable most affecting its appearance being the redox potential of the meat.