The effects of a simulated in vitro digestion model on the viscosity of solutions comprised of high methoxyl, low methoxyl, and low methoxyl amidated pectins were examined in conjunction with a human satiety study with healthy men (n=10) and women (n=15). Participants attended 8 morning sessions with a washout period of one week after a 12 h overnight fast. Self reported measurements were taken for the satiety parameters of hunger, fullness, satisfaction and prospective food intake using 100 mm VAS scales at predetermined time intervals over the course of 3 h. Orange juice solutions of each type of fibre were formulated to be either low viscosity (LV, 0.039±0.007 Pa•s) or high viscosity (HV, 0.14±0.035 Pa•s). The apparent viscosities of an in vitro digestion model simulating the gastric and duodenal phases in the presence of hydrolytic enzymes and bile salts were reported at 10 s-1 and 50 s-1. All pectin types showed varying apparent viscosities during the gastric phases, but showed considerable reductions in viscosity after the final phase. The low-methoxyl low and high viscosity pectin beverages were associated with the greatest effect on human subjective ratings of satiety, and high methoxyl low and high viscosity pectin beverages inconsistently exerting effects on satiety. Thus, some types of pectin are able to increase perception of satiety in humans. However, there was not a strong correlation between apparent viscosity of in vitro digestive fluids and total mean AUC for satiety related questions. Thus, fiber-induced satiety cannot be explained in full by digestate viscosity alone. / NSERC

Enzyme immobilization as a technique attaches free forms of enzyme molecules to stationary support materials to permit enzymes to be reused several times. Bovine trypsin as a model enzyme was immobilized onto controlled pore glass (CPG) beads to investigate the optimum conditions for immobilization, as well as the physico-chemical properties of the immobilized enzyme versus the free form of the enzyme. At pH 9, about 60% of the enzyme protein incubated with CPG was immobilized onto the CPG, and immobilized bovine trypsin activity was determined as 0.265 BAPNA U/g CPG beads. The immobilized bovine trypsin showed lower affinity for its substrate, lower susceptibility to inhibition by soybean trypsin inhibitor and higher thermal stability, while the optimum pH and optimum temperature values were shifted to higher values compared to those of the free enzyme. The immobilized enzyme was evaluated for its capacity to extract carotenoproteins from shrimp shell. After 11 re-uses, the immobilized enzyme retained about 77% of its initial activity, and the total yield of the product from the same immobilized trypsin was 4.3 times higher than a single use of the same amount of the free enzyme. Cunner fish is a cold water adapted, stomachless teleost fish. Cunner fish trypsin possesses some unique properties compared with homologous trypsins from (i) species acclimated to warm temperature regimes, and (ii) species with functionally distinct-stomachs. Cunner fish trypsin was extracted from pancreatic tissue, and immobilized onto CPG beads using glutaraldehyde as cross-linking reagent. The influence of enzyme loading, the properties of the immobilized enzyme in terms of specific activities, and responses to pH and temperature were investigated. The kinetic properties and operational stability of the immobilized cunner trypsin were studied as well. The pH optimum of the immobilized fish trypsin shifted from pH 8.5 to pH 9, and the temperature optimum also increased from 45ºC to 50ºC versus the free form of the cunner enzyme. The catalytic efficiencies (Vmax/Km) of the immobilized fish trypsin were determined for both amidase and esterase reactions, using BAPNA and TAME as substrates and were found to be greater than those of immobilized bovine trypsin. Thus, the immobilized cunner fish trypsin had a higher catalytic capacity for the hydrolysis of both the amide and ester substrates. The operational stability of immobilized fish trypsin was studied by extracting carotenoprotein from shrimp shell. The immobilized fish trypsin retained 75% of its initial hydrolytic capacity after 11 re-uses, and the yield obtained was over 20% higher than that of immobilized bovine trypsin. When the immobilized cunner fish trypsin was applied to digest native pectin methylesterase (PME), it exhibited greater capacity to inactivate the PME than immobilized bovine trypsin. The inactivation efficiency of the immobilized fish trypsin was 20% higher than that of the immobilized bovine trypsin. The inactivation of PME was influenced by PME concentration, incubation time and temperature. In general, higher temperature, longer incubation period, and lower initial PME concentration produced more PME inactivation. PME inactivated by immobilized fish trypsin and bovine trypsin regained part of its activity during storage at 4ºC. The initial PME concentration affected the reactivation period. The kinetic studies indicated that the inactivation rate constants increased and D-values (time to inactivate 90% of the enzyme) decreased with increasing temperature for both immobilized fish trypsin and bovine trypsin. The activation energy (Ea) of PME inactivation by the immobilized fish trypsin was lower than that by the immobilized bovine trypsin, which explains why the immobilized fish trypsin had higher catalytic capacity at various temperatures than immobilized bovine trypsin.

No description available.

Four formulations of cranberry gels using raw materials manufactured by a variety of different processes were examined for their rheological and textural properties. Generally, with higher treatment temperature and holding times, the gels’ rheological and textural properties improved. Gels were examined 24 hours, 48 hours, and 4 days after being prepared. Gels generally showed some further improvement of gel strength during the storage, particularly for gels that were initially processed for the shortest time at the lowest temperature. The pectin molecular properties of five different types of raw cranberry purees were examined for the effect of processing conditions. Pectin was extracted from each type of puree, yield determined and FT-IR analysis was performed in order to determine degree of esterification of each type of extracted pectin. Degree of esterification ranged from ~60-90%. Puree from fresh fruit and cranberry puree concentrate had the highest yield and degree of esterification, whereas purees from the byproducts of puree processing had lower yields and degree of esterification. Purees exposed to elevated temperatures and prolonged heating times showed signs of hydrolysis.

No description available.

Xing, Lei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 111-120). / Abstracts in English and Chinese. / ABSTRACT OF THESIS ENTITLED: --- p.I / 論文摘要 --- p.Ill / ACKNOWLEDGEMENTS --- p.IV / ABBREVIATIONS --- p.V / CONTENTS --- p.VI / LIST OF FIGURES --- p.X / LIST OF TABLES --- p.XII / Chapter CHAPTER 1: --- LITERATURE REVIEW --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.1.1 --- Pectic substances --- p.1 / Chapter 1.1.2 --- Structure and classification of pectins --- p.2 / Chapter 1.1.3 --- Classification of pectinases --- p.4 / Chapter 1.1.4 --- Application of pectinases --- p.5 / Chapter 1.1.5 --- Production of pectinases --- p.5 / Chapter 1.2 --- Lentinula edodes as a source of pectinolytic enzymes --- p.12 / Chapter 1.2.1 --- Taxonomy and Life cycle of L. edodes --- p.12 / Chapter 1.2.2 --- Pectin-degrading enzymes in L edodes --- p.13 / Chapter 1.3 --- Expression systems for fungal pectinolytic enzymes --- p.16 / Chapter 1.4 --- Gene expression analysis --- p.19 / Chapter 1.5 --- Objectives and Long-term significance --- p.20 / Chapter CHAPTER 2: P --- EGTINASES IN L. EDODES --- p.23 / Chapter 2.1 --- Introduction --- p.23 / Chapter 2.2 --- Materials and Methods --- p.25 / Chapter 2.2.1 --- Fungal strains and growth conditions --- p.25 / Chapter 2.3.2 --- Gene models --- p.25 / Chapter 2.2.4 --- Enzyme activity assays --- p.26 / Chapter 2.3 --- Results --- p.30 / Chapter 2.3.1 --- Alignment of 24 candidate pectin-degradation gene models --- p.30 / Chapter 2.3.2 --- Conserved domains in protein sequences of 24 gene models --- p.30 / Chapter 2.3.3 --- Signal Peptide prediction of pectin-degradation gene models --- p.30 / Chapter 2.3.4 --- Pectinases activities in L. edodes --- p.31 / Chapter 2.3.5 --- Growth of mycelia of L. edodes on pectin and non-pectin media --- p.31 / Chapter 2.4 --- Discussion --- p.48 / Chapter 2.4.1 --- Elimination of non-pectinolytic genes --- p.48 / Chapter 2.4.2 --- Conserved domains and active sites of 6 polygalacturonases --- p.49 / Chapter 2.4.3 --- Pectinases activities in L. edodes --- p.49 / Chapter 2.4.4 --- Effect of pectin on the growth of mycelia in L. edodes --- p.50 / Chapter 2.5 --- Conclusion --- p.51 / Chapter CHAPTER 3: --- TRANSCRIPTIONAL PROFILING OF PECTINASES GENES IN L. EDODES --- p.52 / Chapter 3.1 --- Introduction --- p.52 / Chapter 3.2 --- Materials and Methods --- p.57 / Chapter 3.2.2 --- Strain cultivation --- p.57 / Chapter 3.2.3 --- RNA extraction and first strand cDNA synthesis --- p.58 / Chapter 3.2.4 --- Quantitative RT-PCR --- p.58 / Chapter 3.2.5 --- Data analysis --- p.59 / Chapter 3.3 --- Results --- p.62 / Chapter 3.3.2 --- RNA quality of various samples in L. edodes --- p.62 / Chapter 3.3.3 --- Transcription of 14 putative pectinases genes --- p.62 / Chapter 3.3.4 --- Transcription profiling of pectinases genes during the development of L. edodes --- p.62 / Chapter 3.3.5 --- Transcriptional levels of pectinases genes in mycelia of L. edodes grown in different media --- p.63 / Chapter 3.4 --- Discussions --- p.73 / Chapter 3.4.2 --- Transcription profiling of pectinases genes in L. edodes during four developmental stages --- p.73 / Chapter 3.4.3 --- Differential transcriptional levels of pectinases genes in L. edodes mycelia grown in two media --- p.73 / Chapter 3.4.4 --- Effect of pectic substrates on the pectinases genes transcription in mycelia of L. edodes --- p.74 / Chapter 3.5 --- Conclusion --- p.76 / Chapter CHAPTER 4: --- CLONING OF PECTINASES GENES AND THEIR HETEROLOGOUS EXPRESSION IN PICHIA PASTORIS --- p.77 / Chapter 4.1 --- Introduction --- p.77 / Chapter 4.2 --- Materials and methods --- p.79 / Chapter 4.2.2 --- Strain cultivation --- p.79 / Chapter 4.2.3 --- RNA extraction and first strand cDNA synthesis --- p.79 / Chapter 4.2.4 --- Cloning and sequencing of pectinases genes --- p.80 / Chapter 4.2.5 --- Subcloning and expression vector construction --- p.80 / Chapter 4.2.6 --- Growth of Pichia pastoris strains --- p.81 / Chapter 4.2.7 --- Transformation into P. pastoris and vivo screening of multiple inserts --- p.81 / Chapter 4.2.8 --- Expression of recombinant P. pastoris strains --- p.82 / Chapter 4.2.9 --- RNA extraction and transcription analysis of pectinases genes in recombinant Pichia strains --- p.83 / Chapter 4.2.10 --- Enzyme activity assays --- p.83 / Chapter 4.2.11 --- SDS-PAGE --- p.84 / Chapter 4.3 --- Results --- p.88 / Chapter 4.3.2 --- RT-PCR for full-length cDNA of 13 pectinases genes --- p.88 / Chapter 4.3.3 --- Cloning and sequences analysis of 4 putative pectinases genes --- p.88 / Chapter 4.3.4 --- Construction of expression vectors of pectinases genes and transformation to P. pastoris --- p.88 / Chapter 4.3.5 --- Screening of multiple inserts clones --- p.88 / Chapter 4.3.6 --- Recombination and integration of pectinases genes in P. pastoris --- p.89 / Chapter 4.3.7 --- Transcription and expression of pectinases genes in recombinant Pichia strains. --- p.89 / Chapter 4.4 --- Discussion --- p.104 / Chapter 4.4.2 --- cDNA sequences of 4 pectinases genes --- p.104 / Chapter 4.4.3 --- Heterologous expression of 2 pectinases genes in P. pastoris --- p.104 / Chapter 4.4.4 --- Characterization of the pectinases expressed by recombinant Pichia strains --- p.106 / Chapter 4.5 --- Conclusion --- p.108 / Chapter CHAPTER 5: --- CONCLUDING REMARKS --- p.109 / REFERENCES --- p.121

No description available.

When available, wet pack peaches are produced by repackaging sliced and/or diced canned clingstone peaches into a 5-ounce MRE pouch, followed by a thermal process. In this study, wet pack diced peaches were processed in 5-ounce pouches using canned, fresh, and frozen peaches as the raw material. Calcium chloride was added at 0.0 or 0.5% (w/w) to the pouches. The pouches were then stored at 37°C for six months or 50°C for six weeks. The peaches were evaluated for texture, drained weight, pH, brix and sensory evaluations.The canned peaches were not significantly different from wet pack peaches processed using frozen and fresh peaches for overall liking when stored at 37°C for six months. Based on the inability of panelists to differentiate between peach types for overall liking, this study suggests that producers should continue to use canned clingstone peaches as the peach source for wet pack peaches.When calcium chloride was applied to wet pack peaches before thermal processing at 0.5% w/w, a significant increase was seen in the firmness of wet pack peaches after processing. Peaches treated with calcium chloride did not lose firmness as quickly when stored at 50°C for six weeks, but showed no difference in firmness loss rates when stored at 37°C for six months. Sensory analysis of the samples stored at 37°C for six months showed an improvement in firmness scores but a drastic decline in overall acceptance due to the impact of flavor scores.viMultiple levels of calcium chloride showed increased firming effects as the percentage of calcium chloride increased, with negative effects on flavor as the percentage increased. Flavor was not significantly affected by calcium chloride at 0.125% in sensory analysis. This study concludes that to optimize flavor and firmness of wet pack peaches, calcium chloride should only be added at a level up to 0.125%(w/w) that will result in a final pH ≥3.85.

No description available.

The current research was designed to determine the effects of different compositions of a pectin-based emulsion coating on the quality indices and shelf life extension of mango and cucumber. The fruits were treated with pectin-based coating (coated) or kept as such (control), and stored under different temperatures and relative humidities. Samples of fruits were then tested periodically to note the changes in quality as determined by visual observation, weight loss, respiration rate, color, firmness, pH, titrable acidity (TA), total soluble solids (TSS), chlorophyll content, and decay. Coated fruits displayed retarded color development, higher TA, higher chlorophyll content, greater firmness, lower pH, and lower TSS. Loss in weight and CO 2 evolution were also reduced significantly. The results of this research suggested that pectin-based coating increased the shelf life of mango and cucumber more than 100% without perceptible losses in quality.