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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.
281

Effects of potassium sorbate singly and in combination with butyl hydroxyanisole, tertiary butylhydroquinone and propyl gallate on the growth of Staphylococcus aureus S-6 and Salmonella senftenberg

Poerschke, Roger Edward January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
282

Effects of ammonium salts as co-matrices for the analysis of oligonucleotides by matrix-assisted laser desorption/ionization mass spectrometry.

January 1996 (has links)
by Cheng Sau Wan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves [72]-[76]). / TABLE OF CONTENTS --- p.i / ABSTRACT --- p.iv / LIST OF FIGURES --- p.vi / LIST OF TABLES --- p.x / Chapter CHAPTER ONE --- RESEARCH BACKGROUND --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Matrix-assisted laser desorption / ionization mass spectrometry (MALDI) --- p.2 / Chapter 1.2.1 --- Laser desorption methods --- p.2 / Chapter 1.2.2 --- The matrix --- p.3 / Chapter 1.2.2.1 --- Role of the matrix --- p.3 / Chapter 1.2.2.2 --- Features of the matrix --- p.4 / Chapter 1.2.3 --- Mechanisms of ion formation --- p.6 / Chapter 1.2.3.1 --- Desorption process(es) --- p.6 / Chapter 1.2.3.2 --- Ionization process(es) --- p.7 / Chapter 1.3 --- Sequencing of DNA --- p.8 / Chapter 1.3.1 --- DNA sequencing procedure --- p.10 / Chapter 1.3.1.1 --- Generation of the nested set of DNA molecules --- p.11 / Chapter 1.3.1.2 --- Sequence analysis --- p.11 / Chapter 1.3.2 --- MALDI-TOF-MS as a DNA sequencing tool --- p.12 / Chapter 1.3.3 --- MALDI analysis of oligonucleotides --- p.14 / Chapter 1.4 --- Outline of the present work --- p.16 / Chapter CHAPTER TWO --- INSTRUMENTATION AND EXPERIMENTAL --- p.18 / Chapter 2.1 --- Time-of-flight mass spectrometry (TOF-MS) --- p.18 / Chapter 2.1.1 --- Linear time-of-flight mass spectrometry --- p.18 / Chapter 2.1.2 --- Reflectron time-of-flight mass spectrometry --- p.21 / Chapter 2.1.3 --- Ion detection --- p.22 / Chapter 2.1.4 --- Vacuum system --- p.22 / Chapter 2.2 --- Instrumentation --- p.24 / Chapter 2.2.1 --- The laser system --- p.24 / Chapter 2.2.2 --- Ion source and vacuum system --- p.24 / Chapter 2.2.3 --- Flight tube and reflector --- p.27 / Chapter 2.2.4 --- The detector --- p.28 / Chapter 2.2.5 --- Data acquisition and computer control --- p.28 / Chapter 2.3 --- Experimental --- p.29 / Chapter 2.3.1 --- Sample preparation --- p.29 / Chapter 2.3.2 --- Mass spectrometric analysis --- p.30 / Chapter CHAPTER THREE --- USE OF AMMONIUM SALTS AS CO-MATRICES --- p.32 / Chapter 3.1 --- Introduction --- p.32 / Chapter 3.2 --- Experimental --- p.35 / Chapter 3.3 --- Results and Discussion --- p.36 / Chapter 3.3.1 --- Effects of counter-anions --- p.36 / Chapter 3.3.2 --- Effects of matrix materials --- p.40 / Chapter 3.4 --- Conclusions --- p.43 / Chapter CHAPTER FOUR --- USE OF POTASSIUM SALTS AS CO-MATRICES --- p.44 / Chapter 4.1 --- Introduction --- p.44 / Chapter 4.2 --- Experimental --- p.44 / Chapter 4.3 --- Results and Discussion --- p.44 / Chapter 4.3.1 --- Adduct formation --- p.49 / Chapter 4.3.2 --- Signal enhancement --- p.50 / Chapter 4.4 --- Conclusions --- p.52 / Chapter CHAPTER FIVE --- ANALYSIS OF HIGH MASS OLIGONUCLEOTIDES --- p.53 / Chapter 5.1 --- Introduction --- p.53 / Chapter 5.2 --- Experimental --- p.53 / Chapter 5.3 --- Results and Discussion --- p.54 / Chapter 5.4 --- Conclusions --- p.67 / Chapter CHAPTER SIX --- CONCLUSIONS AND FURTHER WORK --- p.68 / Chapter 6.1 --- Conclusions --- p.68 / Chapter 6.2 --- Further work --- p.70 / ACKNOWLEDGMENT --- p.A1 / REFERENCES --- p.R1 - R5
283

Otimização de processos de precipitação química na remoção de fósforo de esgotos sanitários mediante a utilização de sais de ferro como coagulante. / Chemical precipitation optimization of phosphorus from domestic wastewater with a ferric salts as coagulant.

Fernanda Ferrari Gualberto 25 May 2009 (has links)
A presente pesquisa teve como objetivo a otimização de processos de precipitação química na remoção de fósforo de esgotos sanitários mediante a utilização de sais de ferro como coagulante. Analisou-se a remoção de matéria orgânica e produção de lodo obtidas. O trabalho foi desenvolvido com efluentes provenientes de duas estações de tratamento da SABESP, sendo elas a ETE Barueri lodos ativados convencional e ETE Ribeirão Pires tratamento anaeróbio com reatores UASB. Os ensaios de Jar-Test foram conduzidos em laboratório e o coagulante utilizado foi o cloreto férrico. Os resultados obtidos demonstram que a dosagem do coagulante, em ambos os efluentes estudados, resulta na remoção de fósforo total a valores inferiores a 1 mg/L. As dosagens de coagulante necessárias foram de 80 mg/L para a ETE Barueri e 60 mg/L para a ETE Ribeirão Pires. A remoção de carga orgânica também foi alcançada e valores de DBO5,20 inferiores a 10 mg/L são obtidos com dosagens inferiores às necessárias para a remoção de fósforo. A dosagem de coagulante necessária para a remoção de DBO5,20 a valores inferiores a 10 mg/L foi de 40 mg/L. A produção de lodo é o principal problema encontrado quando se utiliza precipitação química, a quantidade de lodo produzida é significativa e deve ser levada em consideração no dimensionamento do sistema de tratamento e disposição final. Incrementos na produção de lodo da ordem de 113% foram obtidos para a ETE Barueri e 51% para a ETE Ribeirão Pires quando foram consideradas as dosagens de coagulante necessárias a remoção de fósforo totais a valores inferiores a 1 mg/L. / The aim of the present study was the chemical precipitation optimization of phosphorus from domestic wastewater with a ferric salt as coagulant. The organic matter removal and the sludge production obtained were analyzed. The study was developed with effluents from two wastewater plants from SABESP, such as ETE Barueri conventional activated sludge and ETE Ribeirão Pires anaerobic treatment with UASB reactors. Jar-Test tests were done in laboratory and the coagulant used was the ferric chloride. The results show that the coagulant dosage, in both effluents studied, results in a total phosphorus removal to values lower than 1 mg/L. The necessary coagulant dosages were 80 mg/L to ETE Barueri and 60 mg/L to ETE Ribeirão Pires. The organic matter removal also was obtained and values of BOD lower than 10 mg/L are obtained to lower dosages than the necessary dosage to phosphorus removal. The necessary coagulant dosage to BOD removal to values lower than 10 mg/L was 40 mg/L. The sludge production is the main problem when chemical precipitation is used, the amount of sludge produced is significant and must be taken into consideration in the system project of treatment and final disposal. Increases in the sludge production were around 113% to ETE Barueri and 51% to ETE Ribeirão Pires when the necessary coagulants dosages were considered to total phosphorus removal to values lower than 1 mg/L.
284

Applications of hypervalent iodine reagents : from enantioselective copper-catalysed arylation-semipinacol cascade to methionine functionalisation for peptide macrocyclisation

Lukamto, Daniel Hartoyo January 2018 (has links)
The unifying theme of this thesis is the exploitation of the reactivity of aryliodonium salts as electrophile transfer reagents. In the first part of the thesis, diaryliodonium salts are employed as arylation reagents for the enantioselective copper-catalysed arylative semipinacol rearrangement (SPR) of various tertiary allylic alcohols. This cascade reaction is a rare example of asymmetrically activating SPR using carbon electrophiles. Different substrate classes - including dihydropyran, indene and dihydronaphthalene moieties - are converted to enantioenriched beta-aryl spirocyclic ketones in excellent yields and enantioselectivities, and often as a single diastereomer. These are in turn useful functional handles for transformations into other moieties, including further rearrangements via Baeyer-Villiger oxidation. In the second part of this thesis, a two-step process for the macrocyclisation of native peptides via a non-natural linkage is developed. This study exploits previous work conducted in the group on the use of aryliodonium salts as methionine-selective diazoacetate transfer reagents. The functionalised methionine is in turn used for an intramolecular rhodium-catalysed insertion into tryptophan. Eventual translation onto solid-phase enables facile access into various macrocyclic peptides.
285

Silver-halophenylethynide and silver-nitrophenylethynide supramolecular synthons for the construction of coordination networks.

January 2009 (has links)
Wang, Minji. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 91-97). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii / 摘要 --- p.iii / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Weak Intermolecular Interactions --- p.1 / Chapter 1.1.1 --- Van der Waals Interaction --- p.1 / Chapter 1.1.2 --- Hydrogen Bonds --- p.2 / Chapter 1.1.3 --- π…π Interactions --- p.4 / Chapter 1.1.4 --- Lone-Pair…Aromatic Interactions --- p.5 / Chapter 1.1.5 --- Halogen…Halogen Interactions --- p.6 / Chapter 1.2 --- Argentophilic Interaction --- p.7 / Chapter 1.3 --- Silver Acetylenediide and Silver Arylethynide --- p.11 / Chapter 1.3.1 --- "C2@Agn(n = 6, 7, 8, 9, 10)" --- p.11 / Chapter 1.3.2 --- "Ag4eC=C-C=Cz>Ag4 and R-C=C@=)Agn, (n = 4, 5; R = Aryl, t-Bu)" --- p.12 / Chapter 1.4 --- Research Strategy --- p.14 / Chapter Chapter 2. --- "Coordination Networks Constructed with the Supramolecular Synthon System Rx-CsCzAgn (n = 4,5; Rx = halophenyl)" --- p.16 / Chapter 2.1 --- Crystal Structure of AgC=CC6H4l-4 ´Ø 2AgCF3COO (2.1) --- p.17 / Chapter 2.2 --- Crystal Structure of AgC=CC6H4l-4 . 3AgNO3 (2.2) --- p.20 / Chapter 2.3 --- "Crystal Structure of 2AgC=CC6H3Cl2-3,4 . 5AgCF3COO ´Ø 2CH3CN . H20 (2.3)" --- p.25 / Chapter 2.4 --- Crystal Structure of 4AgC=CC6H4Cl-3 . 6AgC2F5COO ´Ø 5CH3CN (2.4) & 4AgOCC6H4Br-3 ´Ø 6AgC2F5COO ´Ø 5CH3CN (2.5) --- p.28 / Chapter 2.5 --- Crystal Structure of 2AgC=CC6H4Cl-2 . 4AgCF3COO ´Ø NC(CH2)4CN (2.6) & 2AgOCC6H4Cl-2 ´Ø 4AgCF3COO ´Ø 2CH3CN (2.7) --- p.32 / Chapter 2.6 --- Crystal Structure of AgC=CC6H4F-2 ´Ø 2CF2(CF2COOAg)2 ´Ø 2CH3CN (2.8) --- p.36 / Chapter 2.7 --- Crystal Structure of 4AgC=CC6H4N02-2 ´Ø 10AgC3F7COO ´Ø 4CH3CN . 4H20 (2.9) --- p.39 / Chapter 2.8 --- Summary --- p.41 / Chapter Chapter 3. --- Network Assembly with the Supramolecular Synthon System Rx-C=C3Agw (/i = 3 to 5; Rx = nitrophenyl) --- p.43 / Chapter 3.1 --- Crystal Structure of AgC=CC6H4N02-2 ´Ø 3AgC2F5COO . 2CH3CN (3.1) --- p.44 / Chapter 3.2 --- Crystal Structure of AgC=CC6H4N02-4 ´Ø 3AgC2F5COO ´Ø CH3CN (3.2) --- p.47 / Chapter 3.3 --- Crystal Structure of AgC=CC6H4N02-4 ´Ø 4AgCF3COO ´Ø 2CH3CN (3.3) --- p.50 / Chapter 3.4 --- Crystal Structure of AgC=CC6H4N02-4 ´Ø 3AgCF3COO . CH3CN ´Ø 0.5NC(CH2)4CN (3.4) --- p.53 / Chapter 3.5 --- Crystal Structure of AgC=CC6H4N02-4 ´Ø 3AgC2F5COO ´Ø 2CH3CN (3.5) --- p.56 / Chapter 3.6 --- Crystal Structure of AgC=CC6H4N02-4 ´Ø 3AgC2F5COO ´Ø CH3CN ´Ø NC(CH2)4CN (3.6) --- p.59 / Chapter 3.7 --- Crystal Structure of 4AgC三CC6H4NOr4 ´Ø 4AgC3F7COO ´Ø 3CH3CN (3.7) --- p.62 / Chapter 3.8 --- Crystal Structure of 3AgC=CC6H4N02-4 ´Ø 3AgCF3COO ´Ø 3CH3CN (3.8) --- p.66 / Chapter 3.9 --- Crystal Structure of 7AgC三CC6H4NOr4 ´Ø 17AgCF3COO ´Ø 11CH3CN ´Ø H20 (3.9) --- p.68 / Chapter 3.10 --- Crystal Structure of AgC=CC6H4N02-4 ´Ø CF2(CF2COOAg)2. AgCFsCOO . H2O (3.10) --- p.72 / Chapter 3.11 --- Summary --- p.76 / Chapter 3.12 --- Further Development --- p.77 / Chapter 3.12.1 --- Elongation of Ethynide Ligands --- p.77 / Chapter 3.12.2 --- Incorporating More Ethynide Ligands into One Compound --- p.78 / Chapter Chapter 4. --- Experimental --- p.79 / Chapter 4.1 --- Synthesis --- p.79 / Chapter 4.2 --- X-Ray Crystallography --- p.84 / References --- p.91
286

Preparação, caracterização e estudo de dissociação do naproxeno em uma matriz de quitosana / Preparation, characterization and study of dissociation of naproxen in a matrix of chitosan

Medeiros, Ricardo dos Santos 26 July 2019 (has links)
Foram realizados estudos buscando otimizar as condições reacionais para obtenção de um sal (QN) de naproxeno (NAP) e o biopolímero quitosana (QP). Essa matriz (QN) foi utilizada para o estudo do equilíbrio de dissociação do anti-inflamatório. Para tanto, foram estudadas as melhores condições em relação aos parâmetros tempo reacional, temperatura de reação e razão molar dos reagentes. Os produtos foram caracterizados por ressonância magnética nuclear de hidrogênio e carbono 13, 1H e 13C RMN, espectroscopia vibracional na região do infravermelho com transformada de Fourier, FTIR, espectroscopia eletrônica na região do ultravioleta-visível na modalidade reflectância difusa, UV-vis, difração de raios X (DRX) e técnicas termoanalíticas: termogravimetria (TG), análise térmica diferencial (DTA) e calorimetria exploratória diferencial (DSC). Além disso, estudou-se a evolução dos gases por termogravimetria acoplada a espectroscopia vibracional na região do infravermelho (TG-FTIR). Verificou-se que o maior rendimento de sal foi obtido nas seguintes condições reacionais: 24 horas, temperatura de 60°C e razão molar de 1 mol de QP para 1,05 mol de NAP. Este produto de reação foi chamado de QN1. Neste caso, quando calculado o grau de substituição (GS) por meio da técnica de RMN 13C, observou-se um GS de 19,1 %, sugerindo uma neutralização do grupo NH2 ligado ao C2 do biopolímero com o grupo COOH presente no fármaco. Nos espectros de FTIR foram observadas bandas que correspondem a formação de um produto diferente de QP e NAP, corroborando com a hipóstese de formação do sal QN1. No espectro do UV-vis notou-se as três bandas referentes à absorção dos grupos cromóforos pressentes no sal. Nos difratogramas, verificou-se um pico na região de ~22Ø em QN1, sendo esse já observado como um ombro em QP, porém houve um incremento, além disso, alterações no índice de cristalinidade da quitosana, sugeriram modificações na sua estrutura semicristalina após reação com o NAP. As curvas TG/DTG/DTA mostraram alterações no comportamento térmico do QN1 em relação à QP, evidenciou que a modificação leva a mudanças no comportamento térmico e sugerem a presença de NAP na matriz biopolimérica. A caracterização corroborou hipótese de formação do sal, QN1, pois houveram modificações nos intervalos de perda de massa, assim como, pela razão entre a terceira e segunda perda de massa, pode-se verificar um ganho de estabilidade. Com objetivo de melhorar a capacidade de interação NAP-QP, realizou-se a reticulação das cadeias de quitosana com epicloridrina. No entanto, a reação teve um menor rendimento quando comparada com o sal não reticulado. Verificou-se pelas diferentes técnicas de caracterização, sobretudo, por RMN 13C que, ao invés de organizar e deixar os grupos amino ainda mais suscetíveis à reação, a estrutura da quitosana organizou-se de forma que houve menos interação com o fármaco. Portanto, para os sais QN1 e QPEPIN1 foi realizado o estudo do equilíbrio de dissociação por HPLC, em diferentes pHs 2,00 e 7,00, simulando condições do intestino e estômago, afim de verificar o seu perfil de dissociação e comportamento nessas soluções. Desse modo, verificou-se que em pH 2,00 para QN1 ocorre a dissociação mais rapidamente quando comparada com pH 7,00. Já o sal reticulado QPEPIN1, sua dissociação em pH 2,00 é mais lenta quando comparada com pH 7,00. / Studies were carried out to optimize the reaction conditions to obtain a naproxen (NAP) salt (QN) and the chitosan biopolymer (QP). This matrix (QN) was used for the study of anti-inflammatory dissociation equilibrium. For this, the best conditions were studied in relation to the parameters reaction time, reaction temperature and molar ratio of the reactants. The products were characterized by nuclear magnetic resonance of hydrogen and carbon 13, 1H and 13C NMR, Fourier transform infrared vibration spectroscopy, FTIR, ultraviolet-visible electronic spectroscopy in the diffuse reflectance, UV-vis, diffraction (XRD) and thermoanalytical techniques: thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). In addition, the evolution of gases by thermogravimetry coupled to infrared vibrational spectroscopy (TG-FTIR) was studied. It was found that the higher salt yield was obtained under the following reaction conditions: 24 hours, temperature of 60 ° C and molar ratio of 1 mol of QP to 1.05 mol of NAP. This reaction product was called QN1. In this case, when calculating the degree of substitution (GS) by the 13C NMR technique, a GS of 19.1% was observed, suggesting a neutralization of the NH2 group bound to the C2 of the biopolymer with the COOH group present in the drug. In the FTIR spectra were observed bands corresponding to the formation of a product different than QP and NAP, corroborating with the hypothesis of QN1 salt formation. In the UV-vis spectrum the three bands were observed for the absorption of the chromophore groups present in the salt. In the diffractograms, there was a peak in the region of ~22Ø in QN1, which was already observed as a shoulder in QP, but there was an increase, in addition, changes in the index of crystallinity of chitosan, suggested modifications in its semicrystalline structure after reaction with the NAP. The TG / DTG / DTA curves showed changes in the thermal behavior of QN1 in relation to QP, showing that the modification leads to changes in the thermal behavior and suggest the presence of NAP in the biopolymer matrix. The characterization confirmed the hypothesis of salt formation, QN1, because there were modifications in the intervals of mass loss, as well as, by the ratio between the third and second loss of mass, a stability gain can be verified. In order to improve the NAP-QP interaction capacity, the chitosan chains were crosslinked with epichlorohydrin. However, the reaction had a lower yield when compared to the uncrosslinked salt. It was verified by the different characterization techniques, mainly by 13C NMR that, instead of organizing and leaving the amino groups even more susceptible to reaction, the chitosan structure was organized in a way that there was less interaction with the drug. Therefore, for the salts QN1 and QPEPIN1 the study of the equilibrium of dissociation by HPLC, at different pHs 2,00 and 7,00, was carried out, simulating conditions of the intestine and stomach, in order to verify their profile of dissociation and behavior in these solutions. Thus, it was found that at pH 2.00 for QN1 dissociation occurs more rapidly when compared to pH 7.00. Already the crosslinked salt QPEPIN1, its dissociation at pH 2.00 is slower when compared to pH 7.00.
287

The mechanisms of action of sodium oxalate seed stabiliser molecules under Bayer conditions.

Sipos, Gabriella January 2001 (has links)
Sodium oxalate is one of the many organics present in Bayer liquor. Due to its limited solubility, sodium oxalate can co-precipitate with alumina trihydrate during precipitation. This can have detrimental effects on the final product quality, especially if it occurs in the initial stages of precipitation.Quaternary amine type cationic surfactants can prevent sodium oxalate co-precipitation and increase the tolerable concentration of sodium oxalate in Bayer liquor. Their action is via the inhibition of nucleation or/and the inhibition of crystal growth. This study presents work detailing the effect of quaternary amines on sodium oxalate crystal growth in Bayer liquor.A series of quaternary amines were tested and classified as strong, medium or weak crystal growth inhibitors in plant liquor. The octadecyltrimethylammonium bromide was found to be the most effective under plant conditions.Results will show that while quaternary amines inhibit crystal growth in Bayer liquor, they have no effect on crystallization in synthetic liquor. It has been postulated that the presence of certain organic molecules is required for quaternary amines to crystallization and therefore stabilize the liquor. The inhibition of oxalate crystal growth in Bayer process liquors is due to the plant organics present, and the stabilizing effect of quaternary amines is the result of an interaction between quaternary amines and plant humic material on the oxalate surface. A series of organics, anionic macromolecules and anionic surfactants, have been tested to simulate the behaviour of plant humates, and their inhibitory effect on sodium oxalate crystal growth has been measured.A method for the analysis of the strongest quaternary amine has been adopted, improved and modified in order to fulfil experimental conditions.The CMC of quaternary amines has been determined in liquor. Surface tension ++ / measurements revealed relationships between certain liquor components and quaternary amines.Adsorption isotherms of quaternary amines have been successfully generated in Bayer liquor. Investigations with quaternary amines and plant humics reveal a synergy between the two. Co-adsorption of quaternary amines and plant humates onto the oxalate surface has been found, and the effect of the components on the adsorption behaviour will be discussed. The inhibitory effect and the adsorbed amount of components have been compared. Results revealed a relationship between the amount of plant humates on the surface and the crystal growth inhibition.The nature of the adsorption has been investigated with confocal laser scanning microscopy. These results will show that humic material adsorbs at the edges and in the corners of the crystals. In the presence of quaternary amines, the humic material occupies the main crystal faces as well. The nucleation of sodium oxalate from humic solution and from a mixture of humates and quaternary amine resulted in crystals with different morphology.Fourier Transform Infrared Attenuated Total Reflection Spectroscopy investigations will present the adsorption of quaternary amine on oxalate, and will indicate that the adsorption is pH dependent.
288

Changes of tomato fruit composition in response to salinity

Gao, Yuan, Ph.D. January 1991 (has links) (PDF)
Includes bibliographical references
289

Determination of the optical constants of ash samples from kraft recovery boilers

Samretvanich, Artit 24 April 1997 (has links)
Graduation date: 1997
290

Quality of Applesauce and Raspberry Puree Applesauce as Affected by Type of Ascorbic Acid, Calcium Salts and Chelators under Stress Storage Conditions

Goan, Eric Calvin 01 May 2011 (has links)
Applesauce prepared for the US military is processed as MRE (meals-ready-to-eat) in several forms including Type VI - Applesauce with raspberry puree, and Type VII - Carbohydrate enriched applesauce. Production of MRE applesauce starts with commercially prepared and thermally processed applesauce that is further processed by a military contractor. The further processing includes adjusting pH, ºBrix, and ascorbic acid level, packaging into pouches, and again thermally processing. Both types of the MRE applesauce are very much liked by troops, but under stress storage applesauce darkens and its consumption is drastically reduced. The overall goal of this project was to identify additives to be used during further processing in order to slow darkening when exposed to elevated temperatures during shipping and storage. The specific objective was to determine whether different types of ascorbic acid, calcium salts, or addition of chelators can reduce deterioration under stress storage. Applesauce (AS), applesauce with raspberry puree (RPAS), MRE AS (Type VII) and MRE RPAS (Type VI) for all experiments were provided by Sopakco, Bennettsville S.C. The research was carried out in three phases. From the Phase 1, we learned that Type VII and Type VI darkened at faster rates at the beginning of the storage, but the effects of storage at 50°C for more than 2 weeks overcame any differences caused by further processing. Phase 2 helped us determine the formulations for the processing on the industrial scale. The formulations were: 0.15% L-ascorbic-acid (AA), and 0.15% AA with 300 ppm EDTA for both AS and RPAS, with 0.83% calcium lactate gluconate (CLG) for AS, and 0.15% ascorbyl-palmitate for RPAS. The results from the Phase 3 indicated that AS with addition of CLG and RPAS with total of 0.18% AA had the least total color change. In all samples, accumulation of HMF was related to amount of ascorbic acid with exception of samples with Pal which had the lowest HMF content. Our results indicate that current MRE Types VI and VII may have better stability at stress storage if the level of AA is limited to 0.18% and 0.83% CLG is added to the AS formulation.

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