A quitosana é um biopolímero estudado em diversas áreas, tais como, ambiental, alimentícia, farmacêutica, biomédica e biotecnológica. Ela pode ser obtida de diferentes formas polimórficas de quitina, dentre as quais a forma β tem se mostrado vantajosa, pois favorece modificações químicas mais homogêneas e leva a um produto final menos alergênico. A quitosana pode ser combinada com outros compostos a fim de interagir e/ou reagir com eles e modificar suas propriedades. O objetivo deste trabalho foi estudar como uso de ácido adípico, em substituição ao acético, afeta as propriedades de géis e esponjas de quitosana e de quitosana/gelatina, que foram posteriormente reticuladas com os agentes reticulantes EDC/NHS. As técnicas utilizadas para os estudos foram: reologia, FTIR, MEV, absorção em PBS e ensaios de citotoxicidade. Por reologia, observou-se que o aumento na concentração dos géis de quitosana tornou os géis mais elásticos e viscosos. O mesmo ocorreu na presença de gelatina ou EDC/NHS. O efeito do uso de ácido adípico em substituição ao acético também foi mostrado nos ensaios reológicos, pois os géis com 2% de quitosana e com quitosana/gelatina sem EDC/NHS se mostraram mais elásticos e mais viscosos quando o ácido adípico foi usado. Os espectros FTIR mostraram a presença de interações entre a quitosana e a gelatina e a formação de ligações amidas II após reticulação com EDC/NHS. Na preparação das esponjas observou-se que os géis de quitosana em ácido adípico geravam esponjas instáveis que se desfizeram durante a neutralização, mas essa instabilidade não ocorreu com a blenda. As esponjas preparadas com a blenda foram estudadas após neutralização e o MEV mostrou que o uso de EDC/NHS alterou a morfologia levando a formação de poros interconectados. Nos ensaios de absorção em tampão de PBS foi observado que o uso de ácido acético aumenta a absorção para as esponjas sem EDC/NHS, enquanto para as esponjas com EDC/NHS a absorção é maior quando se usa ácido adípico. Todas as esponjas foram não citotóxicas o que torna esses materiais promissores para serem estudados em aplicações na área médica, tais como material de curativo, implantes, liberação controlada de fármacos. / Chitosan is a natural polymer studied in various fields such as environmental, food, pharmaceutical, biomedical and biotechnology. It can be obtained from different polymorphic forms of chitin, of which the form β has proven advantageous because it promotes more homogeneous and chemical modifications leads to a final product less allergenic. Chitosan can be combined with other compounds and thus further improve its properties. The aim of this study was to analyze how the use of adipic acid, replacing acetic acid affects the properties of gels and sponges of chitosan and chitosan/gelatin, which were subsequently crosslinked with EDC/NHS. The techniques used for these studies were: rheology, FTIR, SEM, absorption in PBS and cytotoxicity assays. In rheology, it was observed that increasing the concentration of chitosan was possible to prepare more elastic and viscous gels. The same occurs in the presence of gelatin or EDC/NHSO. The effect of the use of adipic acid to replace the acetic acid was also shown on rheological measurements, because the gels with 2% chitosan or chitosan/gelatin without EDC/NHS were more elastic and more viscous when the adipic acid has been used. The FTIR spectra showed the presence of interactions between chitosan and gelatin and the formation of amide II Bonds after crosslinking with EDC/NHS. In the preparation of the sponges it was observed that the gels of chitosan with adipic acid generated unstable sponges crumbled during neutralization, but this instability does not occur with the blend. Sponges prepared with the blend were studied after neutralization and SEM showed that the use of EDC/NHS altered the morphology leading to the formation of interconnected pores. The use of acetic acid increases the absorption in PBS for sponges without EDC/NHS, while for sponges with EDC/NHS the absorption is greater when adipic acid was used. All sponges were non-cytotoxic making them promising materials to be studied for applications in the medical field, such as dressing materials, implants, controlled drug release.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references.

Gelatin was extracted from shark and salmon skins by an enzyme aided process. A three factor, two level central composite rotatable design was used to optimize the process. The factors were namely, enzyme: dry fish skin weight ratio, incubation time, and temperature. The data were analyzed by response surface methodology to determine the optimum conditions for the deproteinization, demineralization and extraction process variables. / Optimum conditions for deproteinization of shark skin by trypsin was about 25°C for 3h, and an E/S ratio of 0.08% (w/w). That for salmon was optimum at 25°C for 1 h with an E/S ratio of 1:1000. The ash content of the shark skins was reduced to over 80% at optimum demineralization conditions of 0.7M citric acid at 25°C for 3h. / Demineralised salmon skins treated with pepsin at an E/S ratio of 0.02% (w/w) for 1h at 25°C resulted in maximum gelatin yield ranging from 7--8%. For shark, the maximum yield was between 18--20% at an E/S ratio of 0.02% (w/w) for 3h at 25°C. The chemical and enzyme treatments had an effect on the viscosity, bloom value and molecular weight for both salmon and shark gelatins.

Thesis (Ph. D.)--University of Michigan, 1921.

Thesis (M.S.)--California Polytechnic State University, 2010. / Mode of access: Internet. Title from PDF title page; viewed on April 14, 2010. Major professor: Dr. Lanny Griffin. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Biomedical Engineering." "April 2010." Includes bibliographical references (p. 73-75).

Thesis (Ph. D.)--University of Michigan, 1921.

Thesis (D.Eng.)--University of Delaware, 2009. / Principal faculty advisors: John F. Rabolt and D. Bruce Chase, Dept. of Materials Science & Engineering. Includes bibliographical references.

Resumo: O comportamento reológico de soluções aquosas de gelatina e colágeno hidrolisado (4 e 10 % de sólidos totais) e de gelatina e amido de milho modificado de forma ácida (AMMA) (10 % de sólidos totais) foi estudado através de testes dinâmicos oscilatórios em um reômetro de tensão controlada com geometria cone e placa (60 mm de diâmetro e distância de trabalho de 52 mm). Para todas as concentrações, o módulo de armazenamento, G', aumentou com aumento da freqüência angular. Como esperado, os valores dos módulos correspondentes aos platôs aumentou com o aumento da concentração de gelatina e os valores de G' foram maiores nas soluções contendo amido. Os valores de G' e G' aumentaram com a diminuição da temperatura. O colágeno hidrolisado não apresentou comportamento de gel. A substituição de 25 % de gelatina por amido de milho modificado resultou em valores similares de G' nas amostras contendo somente gelatina. Foi realizado um estudo de separação de fases nas suspensões aquosas de gelatina e AMMA através de microscopia laser confocal, sendo observado que os biopolímeros co-existem, sem separação de fases na amostra em que gelatina e AMMA representam, respectivamente, 37,5 % e 62,5 % dos sólidos totais. Em geral, os demais sistemas apresentaram separação de fases, sendo esta mais pronunciada à medida que as amostras foram ficando enriquecidas com gelatina ou amido. Também foi estudado o comportamento reológico por compressão e as propriedades colorimétricas de gomas de gelatina dietéticas enriquecidas com colágeno hidrolisado e preparadas à base de xarope de maltitol e xilitol. A análise dos parâmetros de textura e o estudo colorimétrico permitiram observar que não há efeitos significativos (p<0,05) na interação entre concentração de gelatina e colágeno hidrolisado quanto à dureza das amostras. Além disso, a maior concentração... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The rheological behavior of aqueous solutions of gelatin and hydrolyzed collagen (4 and 10 % total solids) or gelatin and acid modified corn starch (AMCS) (10 % total solids) was studied. A controlled stress rheometer fitted with a cone and plate geometry (60 mm, gap 52 mm) was used for the dynamic oscillatory shear tests. For all concentrations, the storage modulus increased with the increasing angular frequency. As expected, the modulus plateau values increased with gelatin concentration increasing and G' was higher in the solutions with modified corn starch. G' and G' values attained the highest observed values at lower temperatures. Hydrolyzed collagen did not show gel formation ability. When 25 % of the gelatin content was substituted by AMCS, the observed values of G' were similar to those corresponding to pure gelatin suspensions. A phase separation study was carried out with gelatin and AMCS aqueous suspensions using confocal laser scanning microscopy. The results showed that the two biopolymers co-exist, without phase separation in a system containing 37,5 % of gelatin and 62,5 % of AMCS (based in a 10 wt% total solids). In general, the others systems showed phase separation, which was more intense with increasing gelatin/AMCS concentration. The rheological behavior in compression and the optical proprieties of diet gelatin gummy enriched with hydrolyzed collagen were also studied. The gummies were prepared with maltitol syrup and xilitol. The analysis of texture and opacity parameters showed that significant effects (p<0.05) were not observed in the interaction between the two factors with regard to samples hardness. High concentrations of gelatin and hydrolyzed collagen resulted in a high opacity. The rheological behavior in compression and the optical proprieties of gelatin/AMMA gels were also studied. When AMCS was introduced into gelatin gels, the system structure... (Complete abstract click electronic access below) / Orientador: Vânia Regina Nicoletti Telis / Coorientador: Geórgia Álvares Castro Fernandes / Banca: Rosiane Lopes da Cunha / Banca: Célia Maria Landi Franco / Mestre

abstract: It is widely recognized that dietary protein induces greater satiety compared to carbohydrate and fat. Two separate trials were conducted to assess the use of protein as a dietary approach to manage energy intake (EI). The first, crossover trial, examined 24&ndash; hour EI after consuming a high protein bar (HP) vs. a high carbohydrate (HC) bar upon awakening on two separate days and a control, no bar day. Of the 54 participants who entered the trial, 37 subjects completed the study in its entirety. Results showed there was no significant difference in mean EI between the intervention days when the bars were consumed and the control day. The subjects consumed 1752±99 kcal on the control day, and 1846&plusmn;75 and 1891&plusmn;110 kcal on the days the HP and HC bars were consumed, respectively (P=0.591). However, compared to the control day, snack bar ingestion was significantly related to an increase in EI for the subjects who self-reported high weekly physical activity levels (n=11) (+22%; P=0.038 and +45%; P=0.030, HP and HC bars, respectively). These data suggest that individuals who have moderate to low physical activity levels compensate for the ingestion of energy bars (regardless of protein content) over a 24&ndash;hour period. The second parallel-arm, pilot trial examined the effect of 6 g daily gelatin ingestion vs. control on EI and weight change in healthy, overweight and obese women who initiated a walking program. Of the 37 women who entered the trial, 28 completed the six week trial. The results showed activity level (steps/d) increased in both groups (+ 22%, P=0.022). There was a significant group difference in mean EI at week 6 vs. baseline (&ndash;174&plusmn;612 kcal/d and +197&plusmn;320 kcal/d, P=0.001; gelatin and control groups, respectively). However, there was no significant between group difference for changes in weight, percent body fat and waist circumference. Those subjects having baseline Disinhibition scores of &ge;12 gained significantly more weight throughout the study vs. those scoring <12 (P=0.004). These results indicate that daily gelatin ingestion may be a practical strategy for controlling EI among overweight and obese women initiating an exercise program. / Dissertation/Thesis / Ph.D. Physical Activity, Nutrition and Wellness 2012

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