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This thesis describes a way to achieve higher conversion rates of sugars from lignocellulosic biomass that can then be used for cellulosic ethanol production. Using oat hulls as the biomass, several chemical and physical pretreatment techniques were explored to overcome the recalcitrance and allow access to cellulose and hemicellulose. Experimentation with enzyme cocktails and dosing was done to obtain the highest conversions of cellulose and xylan to produce sugars. High solids-loading of the substrate, 14-16%, enabled higher conversion rates and would amount to lower cost of production in a commercial facility; however, end-product inhibition by the accumulation of inhibitors is also realized. To remove inhibition, a solid-liquid separation step was implemented which allowed enzymes to operate at a higher efficiency. The best combination of pretreatment and enzymatic hydrolysis led to a glucose of 89% and xylose yield of 84%, for trials conducted in a 20L bioreactor.

Thesis (Ph.D.)--Tufts University, 1975. / Submitted to the Dept. of Chemistry. Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (Ph. D.)--University of Hong Kong, 1993.

Orientador: Antonio José Goulart / Banca: Renata Bonini Pardo / Banca: Hamilton Cabral / Resumo: O leite de búfala representa 12% da produção mundial de leite, com maiores teores de proteínas e gorduras que o de vaca. O soro de leite é o co-produto da indústria queijeira que vem sendo, muitas vezes, descartado no meio ambiente, causando grande impacto ambiental em função de sua constituição rica em proteínas e lactose. Hidrólise enzimática é um avanço tecnológico importante por melhorar propriedades físicas, químicas e funcionais dessas proteínas. O objetivo do trabalho foi produzir hidrolisados protéicos a partir das proteínas presentes no soro do leite de búfala e simular a digestão in vitro pelo método da dialisabilidade. O soro lácteo bubalino foi dialisado para retirada de lactose e pequenos peptídeos e aminoácidos, e tratado com caulim para adsorção da gordura. Os produtos de médio e alto grau de hidrólise foram obtidos por ação da pepsina, tripsina, quimotripsina e carboxipeptidase A em pHs e temperaturas específicos, adicionados ao soro conjuntamente e em separado, em diferentes tempos de hidrólise. A determinação quantitativa de proteínas, aminoácidos, lactose e gordura foram realizadas segundo os métodos Bradford (1976), cromatografia líquida de alta eficiência, Miller (1959) e Gerber, respectivamente. A caracterização qualitativa das proteínas e produtos de hidrólise fez-se por eletroforese não-desnaturante (PAGE) e desnaturante (SDS-PAGE). Os ensaios de biodisponibilidade dos produtos de hidrólise foram realizados pelo método in vitro da dialisabilidade segundo metodologia descrita por Luten et al. 1996. Os resultados encontrados para o soro deslactosado e desengordurado foram 6,53g prot.L -1 , redução de 99% de lactose e < 0,10 % de gordura. Bandas protéicas... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Buffalo milk represents 12% of world production of milk, with high protein and fat content of the cow. The whey is the co-product of cheese industry that has been often discarded into the environment, causing great environmental impact due to its rich protein and lactose constitution. Enzymatic hydrolysis is an important technological advance to improve the physical, chemical and functional properties of these proteins. The objective of this research was to produce protein hydrolysates from whey proteins present in buffalo milk and to simulate the digestion in vitro by the method of dialyzability. The whey was dialyzed to remove lactose and small peptides and amino acids, and treated with kaolin for fat adsorption. The partial and total hydrolysates were obtained by the action of pepsin, trypsin, chymotrypsin and carboxypeptidase A in specific pH and temperature, added to the whey together or separately at different times of hydrolysis. Quantitation of proteins, amino acids, lactose and fat were performed according to Bradford (1976), HPLC, Miller (1959) and Gerber respectively. The qualitative characterization of proteins and hydrolysis products was made by PAGE and SDS-PAGE. Tests of absorption of hydrolysis products were performed in vitro by dialyzability. The results for dialyzed and defatted whey was 6.53 g prot L -1 , reduction of 99% lactose and <0.10% fat. Protein bands... (Complete abstract click electronic access below) / Mestre

No description available.

Nature creates high performance materials under modest conditions, i.e., neutral pH and ambient temperature and pressure. One of the most significant materials is the plant cell wall. The plant cell wall is a composite of oriented cellulose microfibrils reinforcing a lignin/hemicellulose matrix. In principle, the plant cell wall composite is designed much like a synthetic fiber-reinforced polymer composite. Unlike synthetic composites, the plant cell wall has an excellent combination of high modulus, strength, toughness and low density that originates in the optimal interactions between the biopolymers. Therefore, to produce high performance composites, a unique route may be to mimic a biological system like the plant cell wall. The present work focuses on understanding the thermodynamics of biopolymer assembly to exploit the process in vitro. In our system, we use an already polymerized nanocellulose template and polymerize phenolic monomers on the template using a peroxidase enzyme. In the first part, we have polymerized phenol using horseradish peroxidase (HRP) in the presence of TEMPO-oxidized nanocellulose. Similar to native plant cell wall structures, the polyphenol-nanocellulose composite had intimate mixing of polyphenol and cellulose at the nanoscale with the presence of cellulose promoting a uniquely organized structure. The obtained composite material showed synergy that enhanced the thermal stability, hydrophobicity, and possibly mechanical properties. In the second part, monolignol coniferyl alcohol was polymerized in the presence of nanocellulose by the same procedure. A comparison between the polyphenol composite and poly(coniferyl alcohol) (PCA) composite revealed that the propanyl substitution imparted flexibility to the PCA molecules so that they could bend and form a hollow globule structure to envelope nanocellulose inside. Polyphenol could not do this because of its rigidity. / Master of Science

As celuloses nanocristalinas (CNC) são partículas de, pelo menos, uma dimensão nanométrica, possuem baixa densidade, alta resistência e área de superfície para realizar modificações químicas, podendo melhorar as propriedades de materiais compósitos. O método mais tradicional para isolar CNC é por hidrólise ácida com ácido sulfúrico, porém este procedimento apresenta desvantagens. Além disso, a ação não seletiva do ácido também ataca as regiões cristalinas levando a um baixo rendimento de produção, e a obtenção de uma suspensão muito diluída de açúcares solubilizados e outros compostos indesejáveis, o que inviabiliza a recuperação dos açúcares. Outra possibilidade para o isolamento de CNC envolve a utilização de preparos enzimáticos de celulases, uma alternativa promissora. Porém, a utilização de baixa carga de polpa celulósica e alta quantidade de enzima tipicamente utilizadas na rota enzimática para obter nanocristais são fatores limitantes. A fim de tentar superar estes problemas, este trabalho teve como objetivo avaliar um sistema de tratamento enzimático em duas etapas para possibilitar a condução do tratamento enzimático em alta concentração de polpa celulósica e baixa dose de enzimas e permitir a produção de CNC e recuperar os açúcares solubilizados em alta concentração. Os resultados mostraram que ao realizar uma hidrólise com baixa carga de sólidos e com suplementação de ?- glicosidade foi possível obter uma conversão de celulose 30% maior, mas uma significativa redução da eficiência enzimática foi observada quando a carga de sólidos foi aumentada, mesmo utilizando a suplementação.Por meio do sistema de duas etapas, foi possível obter uma conversão de celulose e uma concentração de açúcares relativamente alta, além de obter CNC com propriedades comparáveis as obtidas em situações tradicionais de hidrólises. No entanto, o diferencial da hidrólise aplicando o sistema de duas etapas se caracterizou pela utilização de, aproximadamente, metade da quantidade de enzimas utilizadas nas hidrólise tradicionais. Alem disso, o sistema em duas etapas possibilitou a reciclagem das enzimas não adsorvidas para reações de hidrólises subsequentes, se mostrando mais um fator de destaque para a área de conversão enzimática. Conclui-se, portanto, que este sistema se mostrou muito eficiente e promissor o que é interessante do ponto e vista econômico para processos subsequentes à hidrólise. / Nanocrystalline celluloses (CNC) are particles of at least one nanometric dimension, have low density, high strength and surface area to perform chemical modifications, and can improve the properties of composite materials. The most traditional method for isolating CNC is by hydrolysis with sulfuric acid, however this procedure has drawbacks. In addition, the non-selective action of the acid also attacks the crystalline regions leading to a low yield of production, and obtaining a very diluted suspension of solubilized sugars and other undesirable compounds, which impairs prevents the recovery of sugars. Another possibility for the isolation of CNC involves the use of enzymatic preparations of cellulases, a promising alternative. However, the use of low cellulosic pulp load and high amount of enzyme typically used in the enzymatic route to obtain nanocrystals are limiting factors. In order to overcome these problems, this work had as objective to evaluate a system of enzymatic treatment in two stages to enable the conduction of the enzymatic treatment in high concentration of cellulose pulp and low dose of enzymes and to allow the production of CNC and to recover the solubilized sugars in high concentration. The results showed that when hydrolysis was carried out with low solids loading and with ?-glycoside supplementation, 30% higher cellulose conversion was achieved, but a significant reduction of the enzymatic efficiency was observed when solids loading was increased, even using by means of the two-stage system, it was possible to obtain relatively high cellulose conversion and sugar concentration, in addition to obtaining CNCs with properties comparable to those obtained in traditional hydrolysis situations. However, the differential of the hydrolysis applying the two-stage system was characterized by the use of approximately half the amount of enzymes used in traditional hydrolysis. In addition, the two-step system allowed the recycling of the non-adsorbed enzymes to subsequent hydrolysis reactions, showing another important fator for the enzymatic conversion area. It is concluded, therefore, that this system proved very efficient and promising what is interesting from the economic point of view of processes subsequent to the hydrolysis.