The goal of this research was the development of a method to extract pure (1,3/1,6)-β-glucans from Saccharomyces cerevisiae. These β-glucans are of pharmaceutical importance because an animal’s immune system can recognize glucan molecules, and these molecules can act as immunomodulators, essentially turning on the immune system. The problem in the past has been that previously published methods produce β-glucans with low side chain lengths and few branching occurrences. This issue was tackled by a multivariable approach that reduced extraction steps, initial sample size, and concentrations of reagents used. This method has been shown to produce greater yields of β-glucans while maintaining high purity. Analyses such as 1H-NMR and GC-MS have been used to confirm the content of the extracted glucans. Ideally, this research will generate interest for further β-glucan studies and ultimately be utilized pharmacologically with immunocompromised individuals.

β-D-Glucan has been proposed to suppress appetite related perceptions thus contribute favourably to the regulation of energy intake and the increasing obesity problem in North America. Due to its low concentrations in grains, the challenge has been to produce β-glucan concentrates that can be incorporated into foods without adversely affecting product attributes. Therefore in the first part of the study, a protocol for the concentration of β-glucan, based on protein-polysaccharide incompatibility, was investigated. The extract obtained was utilized in the second part, where the effect of beverages with increased β-glucan content on perceived satiety and blood glucose, at different fibre concentrations was studied. Twenty nine healthy adults participated in this study. 5 beverage pre-loads, containing between 0-2.5 g of β-glucan in 500 mL of the sample, were ingested 120 min before the given meal. Results showed a trend towards a decrease in appetite scores with increasing β-glucan content of the beverages, as well as differences in the blood glucose readings, though these were not significant, and could not solely be attributed to β-glucan content due to differences in beverage composition.

Health benefits of high molecular weight (MW) β-glucans are well documented. Therefore, understanding and controlling depolymerization of β-glucan in baked products, would increase the effectiveness of β-glucan to confer health benefits. In this study we demonstrated that endogenous β-glucanase in wheat kernels are responsible for the depolymerization of β-glucans. A protocol was developed based on the Megzayme procedure to detect low levels of β-glucanase activity in wheat flour. This was confirmed by using HPLC-Calcofluor detection to monitor molecular weight changes. The distribution of β-glucanase in wheat kernels was also investigated. The effect of genotype, location, planting season and environmental factors on the level of endogenous β-glucanase in selected wheat cultivars was investigated using different wheat varieties planted under different condition and different seasons. Furthermore, kinetics of β-glucan depolymerization by endogenous glucanase in two dough systems with different moisture content was investigated. The results demonstrated that enzymes with β-glucanase activity are concentrated primarily in the outer layer of wheat kernels. Also genotype, environmental conditions and agronomic practice all had significant effects on the β-glucanase activity in wheat flours and poor harvesting conditions can significantly increase β-glucanase activity level in wheat. The kinetics results demonstrated that moisture content, incubation time and levels of endogenous β-glucanase activity of the system had significant impact on the final MW of β-glucan in the dough. Among all factors investigated, moisture content had the greatest impact. This study presents opportunities for industry to fortify baked products with high molecular weight β-glucan. / Ontario Ministry of Agricultural Food and Rural Affairs

The aim of this study was to understand the cellular mechanisms in enterocytes, which may decrease glucose uptake by viscous oat β-glucan. An in-vitro cell model examined the effect of diffusion limitation, fluid shear stimulation, and increased intestinal stretching. Mechanical stimulation of IEC-6 was assessed. A Flexcell Cell Streamer device applied different fluid flow stresses on cells. Flexcell FX-4000 was used for biaxial stretching of the cells. Following the confirmation of appropriate use of the cell model, the results indicated that high viscosity oat β-glucan might provide a physical barrier limiting diffusion of nutrients to the cells apical surfaces. Western blot analysis confirmed weak mechanical stimulation on the cells. Mechanical stimulation did not influence glucose uptake. Strain-induced cells showed lower activities in their glucose uptake. In conclusion, there may be a significant contribution of direct effects of the viscosity of oat β-glucan on cellular mechanisms of uptake in enterocytes.

Barley has been receiving increased attention as a human food due to the health benefits associated with β-glucan fiber and its potential as a low glycemic index (GI) functional food. Research has shown a relationship between the physico-chemical properties of β-glucan and the physiological effects, which may be altered by processing. However, it is not known if the physiological effects of consuming barley are affected by variations in chemical composition among cultivars or by common processing methods such as pearling or milling. The primary objective of this thesis was to characterize the effects of differences in cultivar starch and fibre content, level of pearling and milling on the GI, satiety and the physico-chemical properties of β-glucan. Nine barley cultivars varying in starch-type and β-glucan content were studied in three experiments in separate groups of ten healthy participants. Blood glucose and satiety ratings were measured and the GI was calculated. Total starch, total fibre, β-glucan, molecular weight (MW), solubility and β-glucan viscosity were determined in vitro. Results showed that GI varied by cultivar (CDC-Fibar, 26 ± 3 vs. AC-Parkhill, 35 ± 4, P < 0.05) and pearling (WG, 26 ± 4 vs. WP 35 ± 3, P < 0.05). When two cultivars were milled and processed to wet pasta the GI increased by 184% (P < 0.05). The pearled wet pasta had a significantly lower GI compared to the whole grain (P < 0.05). Boiled barley kernels tended to elicit greater satiety than white bread, but the difference was not significant. In both the boiled barley kernels and the wet pasta, pearling did not affect the MW, viscosity and solubility. MW did not significantly differ between cultivars but solubility and viscosity did (P < 0.05). The wet pasta had significantly lower MW, solubility, viscosity but not β-glucan content than the boiled barley kernels (P < 0.05). In conclusion, pearling did not have an effect but milling and extruding resulted in significant reduction in MW, solubility and viscosity. The GI of barley is influenced significantly by cultivar, pearling and milling. Further studies are required to determine the effect on satiety.

Barley has been receiving increased attention as a human food due to the health benefits associated with β-glucan fiber and its potential as a low glycemic index (GI) functional food. Research has shown a relationship between the physico-chemical properties of β-glucan and the physiological effects, which may be altered by processing. However, it is not known if the physiological effects of consuming barley are affected by variations in chemical composition among cultivars or by common processing methods such as pearling or milling. The primary objective of this thesis was to characterize the effects of differences in cultivar starch and fibre content, level of pearling and milling on the GI, satiety and the physico-chemical properties of β-glucan. Nine barley cultivars varying in starch-type and β-glucan content were studied in three experiments in separate groups of ten healthy participants. Blood glucose and satiety ratings were measured and the GI was calculated. Total starch, total fibre, β-glucan, molecular weight (MW), solubility and β-glucan viscosity were determined in vitro. Results showed that GI varied by cultivar (CDC-Fibar, 26 ± 3 vs. AC-Parkhill, 35 ± 4, P < 0.05) and pearling (WG, 26 ± 4 vs. WP 35 ± 3, P < 0.05). When two cultivars were milled and processed to wet pasta the GI increased by 184% (P < 0.05). The pearled wet pasta had a significantly lower GI compared to the whole grain (P < 0.05). Boiled barley kernels tended to elicit greater satiety than white bread, but the difference was not significant. In both the boiled barley kernels and the wet pasta, pearling did not affect the MW, viscosity and solubility. MW did not significantly differ between cultivars but solubility and viscosity did (P < 0.05). The wet pasta had significantly lower MW, solubility, viscosity but not β-glucan content than the boiled barley kernels (P < 0.05). In conclusion, pearling did not have an effect but milling and extruding resulted in significant reduction in MW, solubility and viscosity. The GI of barley is influenced significantly by cultivar, pearling and milling. Further studies are required to determine the effect on satiety.

The viscous properties of oat beta-glucan in the gut are influenced not only by beta-glucan content, but also solubility and molecular weight. The objective of this study was to determine the effects of oat processing, genotype and growing location on the physicochemical properties of beta-glucan. Five oat genotypes (HiFi, Leggett, CDC Dancer, Marion and CDC Morrison) grown in two locations (Saskatoon and Kernen) were dehulled (untreated) and processed in a pilot facility through kilning (kilned/not flaked) and subsequent steaming and flaking (kilned/flaked). Three oat genotypes (HiFi, Leggett and Furlong) went through a commercial processing including dehulling, kilning and steaming and flaking. Both pilot and commercial scale processing, genotype and growing environment had significant effects on viscosity, molecular weight and solubility of beta-glucan. Results indicate that there is potential for processors to improve the physicochemical/nutritional properties of oat end products through processing of specific oat genotypes from selected growing locations.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 119-147). Available also in a digital version from Dissertation Abstracts.

Glucan phosphate is a water‐soluble, yeast‐derived, (1 → 3)‐β‐D‐glucopyranose polymer that has been demonstrated to be a potent immune stimulant. Glucan phosphate administration is associated with stimulation of immunity and a concomitant increase in resistance to a variety of experimentally induced disease states. Preclinical safety evaluation indicates that glucan phosphate does not induce mortality or significant toxicity over a wide dose range. Phase I clinical data indicate that glucan phosphate will ameliorate immunosuppression, stimulate immunity, decrease susceptibility to infection and alter ultimate outcome in trauma patients following laparotomy or thoracotomy. This work reviews the development, characterization, preclinal and clinical evaluation of glucan phosphate.

Background: Candida albicans is an opportunistic fungal pathogen that induces strong proinflammatory responses, such as IL-1β production. Much less is known about the induction of immune modulatory cytokines, such as the IL-1 receptor antagonist (IL-1Ra) that is the main natural antagonist of IL-1, by C. albicans. Methods: Peripheral blood mononuclear cells (PBMC) of healthy individuals were stimulated with C. albicans and different components of the fungal cell wall. The role of pathogen recognition receptors (PRRs) for the induction of IL-1β and IL-1Ra was investigated by using specific blockers or in PBMC from Dectin-1 deficient patients. Results: C. albicans induced a strong IL-1Ra response, and this induction was primarily induced by the cell-wall component β-glucan. Blocking IL-1Ra significantly increased C. albicans β-glucan hyphae induced IL-1β and IL-6 production. Surprisingly, blocking the β-glucan receptor Dectin-1 or the downstream Syk or Raf-1 pathways only marginally reduced C. albicans-induced IL-1Ra production, while blocking of the complement receptor 3 (CR3), TLR2 or TLR4 had no effect. In line with this, blocking MAP kinases had little effect on Candida-induced IL-1Ra production. PBMC isolated from Dectin-1 deficient patients produced normal IL-1Ra amounts in response to C. albicans stimulation. Interestingly, the IL-1Ra synthesis induced by β-glucan was blocked by inhibitors of the Akt/PI3. K pathway. Conclusions: β-glucan of C. albicans induces a strong IL-1Ra response, which is independent of the β-glucan receptors dectin-1 and CR3. These data strongly argue for the existence of an unknown β-glucan receptor that specifically induces an Akt/PI3. K-dependent anti-inflammatory IL-1Ra response upon recognition of C. albicans.