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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

Towards constructing functional protocells for origin of life studies

Jin, Lin 03 July 2018 (has links)
Earth’s crust and primordial ocean formed more than 4 billion years ago and life is believed to have originated on earth at least 3.6 billion years ago. This suggests that primitive cellular life must have evolved from non-living matter during that period of several hundred million years. To study the transition from chemistry to biology, a simple vesicular system called a protocell is an ideal model that is self-organized and contains informational or metabolic materials. This thesis starts by exploring the replication of a model genetic material under plausible prebiotic conditions. The non-enzymatic copying of RNA was found to be catalyzed by Fe2+, which used to be abundant in aqueous environments on the early anoxic earth. Fe2+ was found to be a better catalyst of non-enzymatic RNA copying and ligation in slightly acidic to neutral pH conditions than Mg2+, the divalent cation used to catalyze these reactions in previous studies. This finding suggests that ferrous iron could have facilitated the replication and evolution of RNA on the prebiotic earth. To gain a better understanding of the properties of protocell membranes, the impact of membrane composition and multi-bilayer structure on non-enzymatic and enzymatic biochemical reactions was studied. A fatty acid/phospholipid hybrid membrane system was proposed as a potential intermediate state in protocellular evolution. This membrane composition was investigated for its stability and permeability, two fundamental features of functional protocells. The system proved stable in the presence of divalent cations and retained permeability to small building block molecule. Vesicles with this composition were shown to host faster non-enzymatic RNA copying, and to enable enzymatic protein synthesis. To study the effects of multi-lamellarity, giant multilamellar vesicles (GMVs) were prepared by an extrusion-dialysis method. Compared with small unilamellar vesicles (SUVs), GMVs show slightly better ability to retain encapsulated RNA, while maintaining good permeability for small charged molecules. The multilamellar structure also promotes non-enzymatic RNA copying, providing preliminary evidence that membranes could also mediate catalytic functions as well as acting as a compartment. / 2020-07-02T00:00:00Z
82

Utilização da celulose de resíduos lignocelulósicos para obtenção de produtos de alto valor agregado / Utilization of cellulose from lignocellulosic residues for obtaining of products with high added value

Candido, Rafael Garcia 13 April 2011 (has links)
Como conseqüência do aumento da produção de cana nos últimos anos, ocorreu o aumento da quantidade de resíduos agroindustriais gerados a partir deste processo, sendo os principais a palha e o bagaço da cana-de-açúcar. O potencial de produção desses resíduos representa em média 14% da massa da cana processada. A celulose é o principal constituinte desses materiais e pode dar origem a outros materiais por meio de reações de derivatização. Entre os derivados de celulose mais importantes, estão os éteres e os ésteres de celulose. A celulose também pode ser fragmentada, a fim de se utilizar seu monômero formador, a glicose. O presente trabalho teve como objetivo extrair a celulose da palha e do bagaço de cana para utilizá-la na produção de dois derivados, o acetato de celulose e a carboximetilcelulose, além de fragmentá-la a glicose, visando a estudar a hidrólise enzimática necessária para produção de etanol celulósico. Para isso, foram testadas duas vias de obtenção da celulose, uma via denominada ácida e outra, denominada alcalina. Ao término de cada etapa das vias, os materiais produzidos foram caracterizados quimicamente com a finalidade de se elucidar o que acontecia em cada etapa. Ao final dos dois processos, o material obtido foi submetido às reações de acetilação e de carboximetilação. Os derivados de celulose foram caracterizados quanto aos seus graus de substituição e por FTIR. Com o acetato de celulose, foram produzidas membranas através de dois métodos distintos, a evaporação de solvente e a inversão de fases. Essas membranas foram caracterizadas fisicamente por MEV, DMA e teste de permeabilidade. Elas também foram testadas quanto à remoção de íons cobre em solução em estado estacionário. Todos os materiais obtidos nas duas vias testadas foram hidrolisados enzimaticamente utilizando-se as enzimas Celluclast 1.5L e ?-glicosidase. Em todas as vias estudadas e para os dois materiais analisados, foram obtidos como produtos finais, materiais com alto teor de celulose (em torno de 90%) e baixo de teor de lignina (menor que 4%), sendo a via alcalina considerada a de melhor desempenho, pois ocorreu menor perda de celulose nessa via do que na via ácida. Foram produzidos acetatos de celulose com grau de substituição 3, ou seja, triacetatos, ideais para a produção de membranas. Contudo, a presença da lignina, mesmo em pequena quantidade, não permitiu que fossem produzidas membranas com alta resistência mecânica. Em geral as membranas foram capazes de remover cerca de 15,0% dos íons cobres em uma solução aquosa. Dos dois métodos estudados, o de inversão de fases foi o que produziu as melhores membranas. Quanto à carboximetilcelulose, foram produzidas CMCs de diferentes características e mais uma vez a lignina interferiu no processo, quanto mais lignina possuía o material antes da produção de CMC, menor foi o grau de substituição obtido. Nas reações de hidrólise enzimática, quanto mais puro era o material em relação ao teor de celulose, maior foi a concentração de glicose no hidrolisado, sendo alcançadas concentrações em torno de 85,00%. / As a consequence of sugarcane increased production in recent years, there was an increased of residues generation from this process, being the straw and bagasse the main ones. The production potential of these wastes represents around 14% of the processed sugarcane mass. Cellulose is the main constituent of these materials and may give rise to other materials by derivatization reactions. Among the most important derivatives of cellulose, are ethers and esters of cellulose. Cellulose can also be fragmented in order to use its monomer, the glucose. The present work aims at extracting the cellulose from sugarcane straw and bagasse to use it in the production of two derivatives, cellulose acetate and carboxymethylcellulose and to fragment it into glucose for studying the enzymatic hydrolysis, which is a required step for ethanol cellulosic production. For this, it was tested two pathways of cellulose obtaining, the acid route and the alkaline route. At the end of each stage of the process, the materials were characterized chemically in order to elucidate what occurred in each step. After finishing both processes, the material was subjected to reactions of acetylation and carboxymethylation. The cellulose derivates were characterized physically for its degree of substitution and for FTIR. The cellulose acetate was utilized to produce membranes through two different methods, the solvent evaporation and the phase inversion. The membranes were characterized for MEV, DMA and permeability test. They were also tested for cooper ions removal. All materials produced at both pathways were hydrolyzed enzymatically for the enzymes Celluclast 1.5L and ?-glucosidase. In all cases, the final material presented high level of cellulose (about 90,0%) and low level of lignin (low than 4,0%). The alkaline route can be considered the one which achieved the best results, since it was in this pathway that the lowest cellulose lost occurred. The cellulose acetates presented a degree of substitution 3, in other words, they are triacetates, ideal for membrane production. Nevertheless, the presence of lignin, even in low amount, did not allow producing membranes with high mechanic resistance. In general, the membranes were able to remove about 15,0% of cooper ions in a aqueous solution. Between the methods carried out, the phase inversion was the one which produced membranes with the best properties. In relation to carboxymethylcellulose, it was obtained CMCs with different characteristics and, once more, the lignin interfered in the process. The more lignin content before CMC production, the less degree of substitution obtained. In the reactions of enzymatic hydrolysis, the highest cellulose purity proportioned the highest glucose concentrations in the hidrolysates, and it was reached conversion values around 85,00%.
83

Lodo de esgoto como matriz orgânica na formulação de fertilizante organomineral para a cultura da soja / Sewage sludge as an organic matrix in the organomineral fertilizer formulation for soybean cultivation

Rodrigues, Mayra Maniero 05 July 2019 (has links)
O lodo de esgoto é associado a altas concentrações de poluentes inorgânicos em amplitudes que podem inviabilizar o uso direto em solo agrícola, de acordo com os limites máximos normatizados pela legislação, cujo destino final são aterros sanitários que, apesar de ser uma alternativa de menor impacto ambiental, é uma prática onerosa e finita. Entretanto, esse material é rica fonte matéria orgânica, macro e micronutrientes para as plantas como boro, cobre, cobalto, ferro, manganês, molibdênio, níquel e zinco para as plantas, comumente deficientes em solos tropicais. Em nosso estudo, exploramos esse subproduto como matriz orgânica para a formulação de um fertilizante organomineral (FOM) como alternativa à adubação mineral convencional para a cultura da soja em solos de Cerrado, além de possíveis alterações na comunidade microbiana do solo. O experimento foi conduzido em casa de vegetação utilizando dois Latossolos Vermelhos distróficos de texturas distintas (argiloso e franco-argilo-arenoso), diferentes doses de aplicação de FOM (40%, 60%, 80%, 100% e 120%) em três formas físicas (granulada, peletizada e farelada), em comparação com a adubação mineral convencional com (M+Mi+S) e sem (M+S) os micronutrientes B e Zn, além do tratamento sem adubação (CT). O delineamento utilizado foi de blocos inteiramente casualizados. As plantas foram conduzidas até os 60 dias após o plantio (DAP) e foram avaliados os parâmetros fitotécnicos pertinentes a massa seca da parte aérea (MSPA), massa seca de raiz (MSR), altura de plantas, diâmetro do colmo e número de nódulos ativos. A análise química da parte aérea (macro e micronutrientes) foi utilizada para cálculo do teor de nutrientes acumulados no tecido vegetal. Para avaliar a atividade microbiana dos solos utilizou-se a respiração basal do solo (RBS), carbono da biomassa microbiana (C-BM) e atividade das enzimas urease, fosfatase ácida e β-glucosidase. Em ambos os solos, tanto o FOM em menores doses (40% e 60%) quanto os tratamentos minerais, apresentaram desempenhos fitotécnicos semelhantes entre si, bem como o acúmulo de nutrientes no tecido vegetal das plantas, exceto para os elementos P, K e B. Não foram observadas diferenças significativas no desenvolvimento das plantas e nos atributos microbiológicos que possam ser atribuídas as formas físicas do FOM. Embora a RBS tenha indicado aumento na atividade microbiana dos solos a partir da adição de doses crescentes de FOMs, isso não refletiu nos demais parâmetros fitotécnicos ou microbiológicos avaliados, indicando que a planta foi a principal moduladora do comportamento da comunidade microbiana e da dinâmica de nutrientes. Adicionalmente, as análises enzimáticas mostraram-se pouco efetivas diante de condições de estresse observadas neste estudo para gerar respostas em função dos tratamentos. Conclui-se que a utilização de lodo de esgoto como matriz orgânica na formulação de FOMs pode ser uma alternativa agronomicamente viável e sustentável à adubação mineral convencional para a fertilização da soja em solos de Cerrado. / Sewage sludge is associated with high concentrations of inorganic pollutants in amplitudes that may make direct use in agricultural soil unfeasible, in accordance with the maximum limits established by legislation, the final destination of which are sanitary landfills, which, despite being a lower impact alternative is an onerous and finite practice. However, this material is rich source organic matter, macro and micronutrients for plants such as boron, copper, cobalt, iron, manganese, molybdenum, nickel and zinc for plants, commonly deficient in tropical soils. In our study, we explored this by-product as an organic matrix for the formulation of an organomineral fertilizer (FOM) as an alternative to the conventional mineral fertilization for soybean cultivation in Cerrado soils, as well as possible changes in the soil microbial community. The experiment was conducted in a greenhouse using two different dystrophic Red Latosols of different textures (clayey and sandy loam), different doses of FOM application (40%, 60%, 80%, 100% and 120%) in three (M + Mi + S) and without (M + S) the micronutrients B and Zn, besides the treatment without fertilization (CT). The design was completely randomized blocks. The plants were harvested up to 60 days after planting (DAP) and the relevant plant breeding parameters were evaluated for aerial dry mass (MSPA), dry root mass (DMW), plant height, shoot diameter and number of nodules active. The chemical analysis of aerial part (macro and micronutrients) was used to calculate the nutrient content accumulated in the vegetal tissue. Soil microbial biomass (C-BM) and activity of the enzymes urease, acid phosphatase and β-glucosidase were used to evaluate soil microbial activity. In both soils, FOM at lower doses (40% and 60%) and mineral treatments presented similar phytotechnical performances as well as nutrient accumulation in the plant tissue of the plants, except for the elements P, K and B. No significant differences were observed in the development of the plants and in the microbiological attributes that can be attributed to the physical forms of FOM. Although RBS indicated an increase in microbial activity of the soils from the addition of increasing doses of FOMs, this did not reflect the other phytotechnical or microbiological parameters evaluated, indicating that the plant was the main modulator of microbial community behavior and nutrient dynamics. In addition, the enzymatic analyzes showed little effectiveness in the stress conditions observed in this study to generate responses depending on the treatments. It is concluded that the use of sewage sludge as an organic matrix in the formulation of FOMs can be an agronomically viable and sustainable alternative to conventional mineral fertilization for soybean fertilization in Cerrado soils.
84

Spectrophotometric measurement automatization for the analysis of enzymatic processes

Nilsson, Karolina January 2010 (has links)
<p>This thesis work consisted of the development of a virtual instrument that automates enzyme activity measurements and spectrum measurements with the spectrophotometer UVmini-1240. The purpose was to expand the functionality of the instrument, to eliminate the human error and to decrease the amount of time spent on measurements. A PC was connected to the UVmini-1240 via a RS-232C interface and the cell position and temperature was regulated with a CPS-240A controller. The new interface allows all the parameters to be set in the same place. It allows a visualization of the continuous monitoring of the sample absorbance and the option to save the data for post-processing. Also a module for measuring the spectrum of a sample in the wavelength range of 190 nm to 1100 nm is included. The graphical programming language LabView was used to develop the virtual instrument. This thesis work also contained measurement series of the catalase enzyme activity. These were carried out to determine the best storage temperature for the catalase solution and to determine the optimal surrounding temperature for the highest activity in the catalase solution. The conclusions were that the activity does not change considerably the first week of storage, not matter the temperature, and that the activity goes down when the surrounding temperature reaches above 30° C. These measurements were part of a bigger project to develop an ultrasonic method for measuring enzyme activity at the Institute of Acoustics at C.S.I.C in Madrid.</p>
85

Study of a torus bioreactor for the enzymatic elimination of phenol

Pramparo, Laura Mariela 19 June 2008 (has links)
Phenols are priority pollutants that are commonly found in a large number of industrial wastewaters. Different processes are currently available for the elimination of phenol from wastewater but present some disadvantages like low efficiency, high energy-consumption, the necessity of acclimatisation of the sludges or the limitation of the treatment capacity. The need to find alternatives has made the enzymatic processes a good option. In the last two decades, several processes were implemented with different enzymes from plants and microorganisms, including peroxidases from several sources, as the horseradish peroxidase.Also, different enzyme configurations, free or immobilised enzyme and different supports for immobilisation have been studied. Substantial attention has been devoted to the covalent immobilisation of enzymes on porous insoluble supports such as glass, alumina, silica, and chitosan.The main novelty of this work is the utilisation of a torus reactor for the removal of organic contaminants from wastewaters. This reactor, which can be considered as a loop reactor, presents some advantages over other stirred tank reactors.The goal of this work is the study of the hydrodynamics of a torus reactor for its further application in the enzymatic elimination of phenol and the coupling of the kinetics and the modelisation.In a first step, the enzymatic elimination of phenol was experimentally studied in the torus reactor. In order to compare the performances, several assays were also carried out with a stirred reactor. A high degree of conversion was obtained for the enzymatic elimination of phenol in both reactors with the tested quantities of phenol. It was concluded that, keeping a ratio of 1:1 between the phenol and the H2O2 initial molar quantities, the highest final reaction conversion was obtained. Using the torus reactor was obtained 97% of phenol conversion when the optimal concentrations of substrates were usedIn order to improve economically the process, the enzyme should be used in a continuous regime over a long time period to exploit it completely. For this reason it was necessary to immobilise the enzyme. This work presents a new configuration that has never been tested: the horseradish peroxidase supported on Eupergit.In a second step, the characterisation using the CFD of the flow-field in a torus reactor of 100 ml, similar to the experimental reactor, was carried out for two different configurations, batch and continuous operating modes. Moreover, the scale-up of the volume of the torus reactor was carried out using CFD for a 300 ml reactor.Finally, the enzymatic reaction of phenol with the HRP was modelled using the CFD coupled to the kinetic model of the enzymatic reaction to the flow simulation. These results allowed the possibility of optimising and scaling-up the process using the CFD modelisation. / Los compuestos fenólicos son contaminantes prioritarios que se encuentran comúnmente en una gran cantidad de efluentes industriales. Diferentes procesos están disponibles actualmente para la eliminación de fenol desde dicho efluentes pero los mismos presentan algunas desventajas como pueden ser una baja eficiencia, un mayor consumo de energía, la producción de lodos conteniendo hierro o limitaciones en la capacidad de tratamiento. La necesidad de encontrar alternativas a estos problemas ha hecho del proceso enzimático una buena opción. En las últimas dos décadas, varios procesos han sido implementados utilizando diferentes enzimas extraídas de plantas y microorganismos como pueden ser las peroxidasas de diversas fuentes, incluyendo la horseradish peroxidasa.Diferentes configuraciones de enzimas, libre e inmovilizada y diferentes soportes para la inmovilización han sido también estudiados. Sustancial atención ha sido dedicada a la inmovilización de enzimas por enlace covalente sobre soportes porosos insolubles tales como vidrio, aluminio, sílice y chitosan. El objetivo de este trabajo es el estudio de la hidrodinámica dentro de un reactor tórico para su posterior aplicación en la eliminación enzimática de fenol y el acople entre las cinéticas y la modelización.En una primera etapa, la eliminación enzimática de fenol es estudiada experimentalmente en el reactor tórico. Con el objetivo de comparar el rendimiento de dicho reactor, varios ensayos se realizaron en un reactor agitado tradicional. Un alto grado de conversión de fenol ha sido obtenido para la eliminación enzimática de fenol en ambos reactores para las cantidades estudiadas de fenol. Ha sido observado que es necesario mantener una relación de 1:1 entre la concentración inicial de fenol y la de peróxido de hidrógeno para lograr la mayor conversión de fenol. Usando el reactor tórico ha sido obtenido un 97% de conversión de fenol cuando las concentraciones óptimas de substratos y enzimas fueron utilizados. Con el objetivo de mejorar económicamente el proceso y hacerlo factible para su uso a escala industrial, la enzima debería ser utilizada en un proceso en continuo sobre un largo período de tiempo para explotarla completamente. Por esta razón, ha sido necesario inmovilizar la enzima. Este trabajo muestra una nueva configuración que no ha sido aún probada: la horseradish peroxidase soportada en Eupergit. Asimismo, la caracterización usando CFD del campo de flujo de un reactor tórico similar al experimental de 100 ml ha sido realizada para un reactor trabajando de forma batch y continua. Un escalado en el volumen del reactor tórico ha sido realizado utilizando CFD para un reactor de 300 ml. Finalmente, la reacción enzimática de fenol con HRP has sido modelada acoplando el modelo cinético obtenido experimentalmente con las simulaciones del campo de flujo dentro del reactor. Estos resultados permitirán la optimización y el escalado del proceso usando CFD.
86

Spectrophotometric measurement automatization for the analysis of enzymatic processes

Nilsson, Karolina January 2010 (has links)
This thesis work consisted of the development of a virtual instrument that automates enzyme activity measurements and spectrum measurements with the spectrophotometer UVmini-1240. The purpose was to expand the functionality of the instrument, to eliminate the human error and to decrease the amount of time spent on measurements. A PC was connected to the UVmini-1240 via a RS-232C interface and the cell position and temperature was regulated with a CPS-240A controller. The new interface allows all the parameters to be set in the same place. It allows a visualization of the continuous monitoring of the sample absorbance and the option to save the data for post-processing. Also a module for measuring the spectrum of a sample in the wavelength range of 190 nm to 1100 nm is included. The graphical programming language LabView was used to develop the virtual instrument. This thesis work also contained measurement series of the catalase enzyme activity. These were carried out to determine the best storage temperature for the catalase solution and to determine the optimal surrounding temperature for the highest activity in the catalase solution. The conclusions were that the activity does not change considerably the first week of storage, not matter the temperature, and that the activity goes down when the surrounding temperature reaches above 30° C. These measurements were part of a bigger project to develop an ultrasonic method for measuring enzyme activity at the Institute of Acoustics at C.S.I.C in Madrid.
87

Production, Fractionation, and Evaluation of Antioxidant Potential of Peptides Derived from Soy Protein Digests

Robinson, Mary Anna January 2010 (has links)
Oxidation plays an important role in the basic processes of life, such as the production of energy and phagocytosis employed by the immune system. However, when an imbalance between oxidants and antioxidants exists in vivo, oxidation can become uncontrolled and result in diseases such as arthritis, cancer, artherosclerosis, and Alzheimer’s Disease. Dietary antioxidants including polyphenolic compounds, proteins, and peptides have been identified as being physiologically functional foods capable of contributing to the restoration of this oxidant-antioxidant balance. The objective of this study was to explore the production of antioxidant soy peptides from a commercially available soy protein isolate (SPI) by enzymatic hydrolysis in a process similar to that occurring in the human digestive tract. In this study Archer-Daniels Midland SPI PRO-FAM 974 was used as a raw material for the production of antioxidant soy peptides. The digestion consisted of enzymatic digestion of the SPI (3.12 wt %) with pepsin (37ºC, pH 1.5) and/or pancreatin (40ºC, pH 7.8) either individually or sequentially. The enzyme concentration and digestion time for each enzyme was optimized using a 2^4 factorial experimental design to produce the greatest concentration of peptides quantified in PheGly equivalents by the OPA assay. A maximum peptide concentration of approximately 65 mM PheGly equivalents was achieved in the follow-up digests resulting from this factorial design model, using pepsin (0.15 g/L, 15 minutes) and pancreatin (4.5 g/L, 120 minutes) sequentially to digest the SPI. Fractionation of the peptides by sequential dead-end membrane ultrafiltration with molecular weight cut-offs (MWCO) of 3 kDa and 1 kDa was performed to produce peptide fractions with increased antioxidant capacity. The permeate flux as a function of time was fit to empirical models, revealing that the membrane fouling resulting in the permeate flux decline is largely reversible and most likely the result of cake filtration. Antioxidant capacity was quantified by the DPPH, FCR, and ORAC assays to determine the electron-donating and proton-donating capacities of the soy peptides. The electron-donating DPPH assay was not suitable to quantify the antioxidant capacity of the soy peptides due to poor peptide solubility in the assay media and sensitivity. The electron-donating FCR assay and the proton-donating ORAC assay were used to distinguish between the ultrafiltration and digestion conditions employed to produce the soy peptides and the antioxidant capacity was quantified in equivalence to the standard antioxidant Trolox. The soy peptide fraction with the greatest antioxidant capacity was produced by enzymatic digestion with pancreatin (4.5 g/L, 120 minutes) alone and had a molecular weight cut-off of between 3 kDa and 1 kDa. This fraction had an equivalent antioxidant capacity of approximately 190 mg Trolox/g sample in the ORAC assay and approximately 180 mg Trolox/g sample in the FCR assay. A preliminary linear model for the optimum digestion and ultrafiltration conditions for the production of antioxidant peptides with the greatest ORAC antioxidant capacity was also developed. The model includes a positive pancreatin digestion time term and a negative pepsin digestion time term. No ultrafiltration terms were found to be significant in this preliminary model, but a large constant term persisted. In conclusion, the enzymatic digestion of commercially available SPI with pancreatin and fractionated by ultrafiltration successfully produced a soy peptide fraction with increased antioxidant capacity.
88

Fundamental investigation into oxidoreductase enzymatic bleaching systems

Sealey, James E., II 12 March 1998 (has links)
No description available.
89

Simultaneous Saccharification and Fermentation of Dry-grind Highly Digestible Grain Sorghum Lines for Ethanol Production

Hernandez, Joan R. 2009 May 1900 (has links)
The potential of high digestible grain sorghum (HDGS) with a modified starch protein endosperm matrix to replace corn in ethanol production was investigated using dry grind simultaneous saccharification and fermentation (SSF). Preliminary experiments showed that HDGS yielded higher amounts of glucose and ethanol than normal digestible grain sorghum (NDGS) and corn particularly in the first 48 hrs of fermentation. It was hypothesized that fast conversion of starch to glucose and ethanol during hydrolysis and fermentation are results of improved protein digestibility of HDGS. The invagination of protein structures in HDGS produced a flourier endosperm texture, softer kernels and lower starch content than the normal digestible protein (ND) lines. Highly digestible protein (HD) lines have better pasting properties (significantly lower pasting temperature, faster rate of gelatinization and higher peak viscosity) than ND lines based on the RVA profile. Increasing protein digestibility of the HDGS improved starch digestibility (increased rate of glucose conversion and total glucose yield during saccharification), which is supported by highly significant correlation of turbidity with rate of glucose conversion and efficiency of enzymatic conversion. The efficiency of ethanol conversion is significantly correlated with starch digestibility, pasting properties, and protein digestibility. Results also showed that HD sorghum lines had significantly faster rate of conversion and shorter reaction time needed to achieve completion than ND sorghum lines and corn. Increasing the dry solid concentration from 22% to 30% (w/v) increased the ethanol yield from 8% v/v to 13%v/v. This will allow considerable saving of water, reduced distillation cost and increased ethanol production for a given plant capacity and labor cost. Fineness of grind influences the amount of sugar formed due to variation in surface area of the flour. The hypothesis that finer particles has faster and higher glucose yield, defined as g of glucose converted per g of theoretical glucose, is supported by highly significant correlation of mass fraction of 3 to 60 mu m size range and mass median diameter (MMD) of 60 to 1000 mu m size range with glucose conversion efficiency and glucose conversion rate during saccharification and fermentation.
90

Development of Oxidative Lime Pretreatment and Shock Treatment to Produce Highly Digestible Lignocellulose for Biofuel and Ruminant Feed Applications

Falls, Matthew David 2011 August 1900 (has links)
At present, the United States generates biofuels (ethanol) from corn grain. Unfortunately, low crop yields and limited growth regions result in limited availability. Furthermore, the use of staple food crops for ethanol production has generated a highly controversial food vs. fuel debate. Because of its high abundance and relatively low cost, lignocellulosic biomass is a promising alternative feedstock for biofuel production; however, structural features of lignocellulose limit accessibility of enzymes or microorganisms. These structural barriers include high lignin content, acetyl groups on hemicellulose, high cellulose crystallinity, cellulose degree of polymerization, and small pore volume. To overcome these barriers, a variety of pretreatment processes (chemical and mechanical) have been developed. Oxidative-lime pretreatment (OLP) is highly effective at reducing lignin content and removing acetyl groups from hemicellulose. Combining OLP with a mechanical treatment process greatly enhances the enzymatic digestibility of lignocellulose. Recommended OLP conditions were determined for Dacotah (120 °C, 6.89-bar O2, 240 min) and Alamo (110 °C, 6-89-bar O2, 240 min) switchgrass. Using recommended conditions, 72-h glucan digestibilities (g glucan hydrolyzed/100 g glucan in raw biomass; 15 filter paper units/g raw glucan) of 85.2 and 88.5 were achieved for Dacotah and Alamo, respectively. Adding ball milling to OLP further enhanced glucan digestibility to 91.1 (Dacotah) and 90.0 (Alamo). In previous studies, shock treatment achieved promising results, but was often inconsistent. This work refined shock treatment with a focus on using consistent procedures and performance analysis. The combination of OLP and shock treatment enhanced the 72-h glucan digestibility of several promising biomass feedstocks: bagasse (74.0), corn stover (92.0), poplar wood (94.0), sorghum (71.8), and switchgrass (89.0). Highly digestible lignocellulose can also be used as ruminant animal feed. Shock treatment plus OLP increased the total digestible nutrients (TDNN; g nutrients digested/100 g organic matter) of corn stover from 51.9 (untreated) to 72.6. Adding in pre-washed corn stover solubles to produce a combined feed (17.8 percent corn stover solubles and 82.2 percent shock OLP corn stover) increased TDNN to 74.9. Mixing in enough solubilized protein to match the crude protein content of corn grain further improved TDNN to 75.5, only 12.6 less than corn grain.

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