Thesis (Ph. D.)--Baylor University, 2006. / Includes bibliographical references (p. 222-233).

Thesis presented in partial fulfilment of the requirements for the degree of Master of Technology (Food Technology) Department of Food Technology Faculty of Applied Sciences 2014 / The aim of this study was to evaluate the effect of transglutaminase (TG) and cyclodextrinase (CG) on the rheological characteristics of oat dough and shelf-life characteristics of oat bread with a view to developing oat bread with improved texture and shelf-life. Firstly, the effects of yeast, carboxylmethylcellulose (CMC), plain yoghurt (YG), transglutaminase (TG) and cyclodextrinase (CG) on the mixing, pasting, thermal, quantification of free amino acid groups and protein crosslinking properties of oat dough were investigated through a 25-2 fractional factorial design resolution III with yeast (1.25, 3.25%), CMC (1, 2%), YG (10.75, 33.75%), TG (0.5, 1.5%) and CG (10, 40 μl) as independent variables. Among all the ingredients, only CMC, YG, and TG exhibited significant (p < 0.05) effects on the mixing properties of oat dough while yeast and CG slightly affected it. TG addition increased water absorption (34.80 - 38.45%) and peak resistance (696.40 - 840.30 FU) but decreased the dough softening (93.20 - 67.75 FU) as its level varied from 0.5 to 1.5 g. CG did not significantly (p > 0.05) affect the mixing properties of oat dough. As its level increased from 10 - 40 μl, the water absorption (38.45 - 34.80%), energy at peak (11.45 - 3.75 Wh/kg), peak resistance (840.30 - 696.40 FU) slightly decreased while the softening of oat dough increased from 67.75 to 93.20 FU. The addition of yeast and YG showed significant (p < 0.05) impacts on the pasting properties of oat dough compared to CMC, TG and CG. The storage modulus of oat dough was slightly (p > 0.05) increased by adding TG (180.37 - 202.78 kPa) and CG (170.75 - 175.71 kPa). TG decreased the loss modulus (65.95 - 62.87 kPa) of oat dough while CG increased it from 62.01 - 64.61 kPa. The thermal properties of oat dough were slightly affected by all the ingredients. The denaturation temperature was increased by incorporation of TG (6.53 - 8.33°C) and CG (6.42 - 8.33°C) but there was a decrease of enthalpy due to addition of TG (from 0.76 to –4.05 J/g) and CG (1.11 to –4.05 J/g). Only CG decreased the number of free amino acid groups (0.94 - 0.62) confirming that it catalysed the protein crosslinking of the oat glutelin while other ingredients increased it. Secondly, as CMC, YG and TG affected the mixing, pasting and thermal properties of oat dough, oat bread was baked with carboxylmethylcellulose (CMC), yoghurt (YG) and transglutaminase (TG) following a 33 Box-Behnken design consisting of CMC (1, 2 g), YG (10.75, 33.75 g) and TG (0.5, 1.5 g) as independent variables. The physical and textural analysis of oat bread showed that CMC, YG and TG addition did affect oat bread. TG decreased the springiness (6.47 - 4.14 mm), specific volume (1.61 - 1.54 ml/g) and increased hardness (537.85 - 692.41 N) of oat bread. No significant effect was observed on the colour parameters of crust and crumb of oat bread. Despite the optimal oat bread exhibited a high desirability, its high hardness and low springiness remain some challenges associated with oat bread production. Since it was well established that TG increased hardness and decreased springiness of the optimal oat bread, improvement was needed for the production of best oat bread. Thirdly, Psyllium husks (PH) and cyclodextrinase (CG) were added in five (05) best oat bread formulations such as (1) PH + CG, (2) CG, (3) TG + CG, (4) TG + PH and (5) TG + PH + CG. The best oat bread formulation with low hardness containing PH and CG was further used for sensory and shelf-life studies. The combination of ingredients psyllium husks and cyclodextrinase significantly (p < 0.05) improved the textural properties of best oat bread. It decreased the hardness (94.88 N) and increased the springiness (10.97 mm) of the best oat bread. Fourthly, the sensory evaluation showed that the consumers highly appreciated the crumb colour and texture of the best oat bread than the ones of wheat bread. In addition, they found that there was a strong correlation in crust and crumb colour between wheat and the best oat bread. However, some differences existed between the wheat and best oat bread. The best oat bread exhibited a less preference in taste than its wheat counterpart. The best oat bread positively received an overall acceptability (4.07) as wheat bread (4.22). Fively, the shelf-life studies of the best oat bread revealed that the pH and TVC of the best oat bread were more affected by the time, temperature and the interaction of both parameters (time and temperature) than Total Titratable Acidity (TTA), yeasts and mould as the storage time passed. The best oat bread could safely be stored up to 21 days at refrigeration temperature (5°C) with a Total Viable Count (TVC) load of 105 cfu/g. Finally, using survival analysis for the shelf-life studies of the best oat bread, the mathematical model revealed that the risk of deteriorating increased with the temperature.

Thesis (MSD) --Boston University, Henry M. Goldman School of Dental Medicine, 2015 (Department of Molecular and Cell Biology). / Includes bibliography: leaves 46-50. / Celiac disease (CD) is an autoimmune disorder characterized by enteropathy caused by ingested gluten. Human transglutaminase 2 (TG 2) localized in the lamina propria of the small intestine modifies gluten by deamidating glutamine residues, which enhances gluten binding to T-cell receptors and downstream inflammatory immune responses. Many other human TGs and microbial transglutaminases (MTGs) share a similar catalytic activity with TG2. This study aimed to investigate the presence and activities of oral TGs from both human and microbial origins in whole saliva (WS) and dental plaque of healthy individuals. It also aimed to establish a method and positive control to detect MTG activity from oral bacteria. [TRUNCATED]

Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 117-135).

published_or_final_version / Botany / Master / Master of Philosophy

Transglutaminases (EC 2.3.2.13) are a group of thiol enzymes that catalyse acyl-transfer reaction in which the gamma-carboxyamide groups of peptide-bound glutaminyl residues are the acyl donors. They cause post-translational modification of proteins mainly by protein to protein cross-linking, but also through acyl transfer reaction and deamidation of glutamine residues. / Crude liver and flesh extracts of bluefish (Pomatomus saltatrix ) were investigated to ascertain the effects of storage time and temperature on the stability and activity of transglutaminase (TGase). TGase activity was measured and the enzyme was subsequently characterized using CBZ-L-glutaminylglycine and hydroxylamine as substrates. Frozen bluefish liver and flesh extracts had higher specific activities (0.321 Units and 0.230 Units respectively) in comparison to refrigerated liver and flesh extracts (0.124 Units and 0.071 Units respectively) at the end of a 30 day storage period with the frozen liver extract retaining the highest stability. The optimum temperature for the crude bluefish liver TGase reaction with CBZ-L-glutaminylglycine and hydroxylamine was between 40&deg;C and 45&deg;C. The enzyme was stable at temperatures below 55&deg;C, beyond which it lost activity progressively. The crude enzyme extract was active within the pH range of 6.0-7.5, with an optimum pH of 7.0, and was stable from pH 6.5-8.0. / TGase was partially purified from the frozen liver extract of bluefish by gel filtration on 8ephacryl S-200 HR. The partially purified extract was further characterized with respect to its response to temperature and pH. The effects of sodium as well as calcium chloride and other divalent cations, and the inhibitory effects of various chemicals on the activity of the partially purified TGase were also investigated. The partially purified bluefish TGase had an optimum temperature of 40&deg;C via the reaction with CBZ-L-glutaminylglycine and hydroxylamine. The enzyme was observed to be stable at temperatures below 50&deg;C and approximately 90% of the initial TGase activity was retained at the end of a 30 min incubation period. The partially purified bluefish TGase had a pH optimum of pH 7.5 and was stable within a narrow pH range of 7.0 - 8.0. / The partially purified enzyme showed requirement for calcium (Ca 2+) ions for activity and no activity was observed in the absence of Ca2+. The replacement of Ca2+ by other divalent cations such as Mg2+, Mn2+, Ba2+, Zn2+ and Fe2+ produced various levels of activity with the enzyme, albeit less than that achieved with Ca2+. Increasing NaCl concentrations, 0 - 15mM, did not seem to have an enhancing effect on the activity of partially purified bluefish TGase. TGase was inhibited by sulfhydryl alkylating agents (monoiodoacetic acid (IAA) and N'-ethylmaleimide (NEM)).

Orientador : Carlos Raimundo Ferreira Grosso / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T23:16:33Z (GMT). No. of bitstreams: 1 ChambiMamani_HuldaNoemi_M.pdf: 2171478 bytes, checksum: c08170d38156c56f03a865760dd7dab8 (MD5) Previous issue date: 2004 / Mestrado

No description available.

Orientador: Helia Harumi Sato / Dissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-13T21:55:21Z (GMT). No. of bitstreams: 1 Bagagli_MarcelaPavan_M.pdf: 2162265 bytes, checksum: 1def96dba6cfee03d3797c85fd357d3c (MD5) Previous issue date: 2009 / Resumo: A transglutaminase (TGase, EC 2.3.2.13) é uma enzima que catalisa a formação de ligações cruzadas entre resíduos de glutamina e aminas livres de proteínas formando agregados protéicos. Foi estudado o aumento da escala de produção da transglutaminase de Streptomyces sp. P20, de frascos Erlenmeyer agitados de 50 mL contendo 15 mL de meio de cultivo para fermentador de bancada de 6 L com volume útil de 3 L. Para a fermentação em frascos agitados foi utilizado o meio de cultivo otimizado por MACEDO et al. (2007) e para a fermentação do microrganismo em reator de bancada foi utilizado esse útimo meio de cultivo modificado, composto de extrato de 2,5% de farinha de soja, 2% de amido de batata, 1% de peptona, 0,1% de glicose, 04% de KH2PO4 e 0,2% de MgSO4, ajustado para pH 7,0. Foi estudado, através de delineamento fatorial, os efeitos da temperatura, agitação e aeração na fermentação da linhagem de Streptomyces sp. P20 no reator de bancada e a produção de transglutaminase. O aumento da escala de 200 vezes proporcionou uma elevação na atividade enzimática de 7,2 vezes, e o tempo para obtenção desta atividade foi reduzido de 120 horas para 42 horas de fermentação, utilizando dois estágios de temperatura. A atividade máxima obtida em reator de bancada foi de 2,05 U/mL de caldo fermentado. No estudo da produção da transglutaminase de Streptomyces sp. P20, por fermentação em meio semi-sólido, utilizando-se como substratos farinha de feijão branco e farinha de amendoim, foram obtidos, respectivamente, atividade de transglutaminase iguais a 0,88 U/g de substrato seco e 0,77 U/g de substrato seco. A caracterização bioquica da transglutaminase bruta de Streptomyces sp. P20 foi estudada, bem como a aplicação da enzima em carne bovina e proteína texturizada de soja. Os valores de temperatura ótima e pH ótimo desta enzima foram avaliados, sendo verificado que a temperatura ótima de atividade foi de 35°C e o pH 6,5, sendo encontrada uma segunda faixa de pH ótimo em 9,0, o que pode indicar a presença de isoenzimas. A MTGase mostrou-se estável na faixa de pH 6,0 ¿ 9,0, e at·a temperatura de 35°C em pH 6,0 por 30 minutos. O aminoácido L-cisteína aumentou a estabilidade térmica da MTGase de Streptomyces sp. P20. O efeito de íons metálicos, do EDTA, L-cisteína, L-glutationa e PEG 6000 na atividade da MTGase foram avaliados. Os íons Hg2+, Cu2+, Zn2+ e Mn2+, inativaram a enzima, sugerindo a presença de grupos tiol no seu sítio ativo. O íon Mg2+ aumentou a atividade da MTGase cerca de 100%. A aplicação da MTGase de Streptomyces sp. P20 em carne bovina e em prote?a texturizada de soja foi eficiente quando comparada a aplicação da enzima comercial Activa TG-BP aplicada nas mesmas condições / Abstract: Transglutaminase (TGase, EC 2.3.3.13) is an enzyme that catalyzes cross-linking between the glutamine and free amine residues of proteins leading to the formation of protein aggregates. The scale up of the production of transglutaminase by Streptomyces sp. P20 from shaken flasks to a bench fermenter was studied. Initially, the effect of temperature and agitation on the microorganism was studied in 50 mL conical flasks containing 15 mL of culture medium previously optimized by MACEDO et al. (2007). The production in 250 mL conical flasks containing 50 mL of the same culture medium was then studied. For fermentation in the bench reactor the same medium was used, modified, containing extract of 2.5% powdered soy, 2% potato starch, 1% peptone, 0.1% glucose, 0.4% KH2PO4 and 0.2% MgSO4, pH 7.0. A factorial design was used to study the effects of temperature, agitation and aeration on the fermentation of the strain Streptomyces sp. P20 in a 6L bench fermenter. The x200 scale up led to a x7.2 enhancement in enzymatic activity, and the fermentation time decreased from 120 h to 42 h using two temperature (from 34°C during the first 24 hours to 26°C for the remaining time) and agitation (from 350 rpm during the first 24 hours to 150 rpm for the remaining time) shifts. The maximum transglutaminase activity obtained was 2.05 U/mL. In the solid state fermentation study using semi-solid media containing white bean flour and peanut flour, transglutaminase activities of 0.88 U/mg dried substrate and 0.77 U/mg dried substrate, respectively, were obtained. The biochemical characterization of the crude transglutaminase obtained from Streptomyces sp. P20 and its application in beef and texturized soy protein were studied. The optimum temperature and pH values for MTGase activity were investigated, exhibiting optimum activity at 35°C and at both pH 6.5 and pH 9.0, probably due to the presence of an isoenzyme. The enzyme was stable in the pH range from 6.0 ¿ 9.0, and at temperatures of up to 35?C it was stable for 30 minutes at pH 6.0. The amino acid Lcysteine enhanced the thermal stability of the MTGase from Streptomyces sp. P20. The effects of metal ions, EDTA, L-cysteine, L-glutathione and PEG 6000 on the activity of MTGase were investigated. The ions Hg2+, Cu2+, Zn2+ and Mn2+ inhibited enzyme activity, suggesting the presence of a thiol group at the active site of the enzyme. The ion Mg2+ increased MTGase activity by 100%. The application of MTGase from Streptomyces sp. P20 in beef and texturized soy protein was efficient when compared to the application of commercial Activa TG-BP under the same conditions / Mestrado / Mestre em Ciência de Alimentos

Thesis (doctoral)--University of Helsinki, 2007. / Includes bibliographical references. Also available on the World Wide Web.