ORCID Profile
0000-0003-1293-9392
Current Organisations
University of Queensland
,
Murdoch University
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Publisher: Elsevier BV
Date: 05-2009
Publisher: Elsevier BV
Date: 10-2012
DOI: 10.1016/J.FOODCHEM.2012.03.131
Abstract: The kinetics of passage of a model bile salt and complete porcine bile across a dialysis membrane, in the presence and absence of two cereal-derived soluble dietary fibre polysaccharides, were studied as a model for passage across the unstirred water layer that lines the small intestine. A first-order kinetic analysis allowed rate coefficients to be derived which quantified the effectiveness of barley mixed linkage β-glucan and wheat arabinoxylan in retarding the transport of bile. For both, a model bile salt and complete porcine bile, rate coefficients decreased with both concentration and viscosity. A combination of viscosity and molecular interaction effects is suggested to control the effect of the two polysaccharides on the transport of bile.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6FO00383D
Abstract: The aim of this study was to investigate the effects of cereal soluble dietary fibres (SDFs), β-glucans (BG) from oat and barley as well as arabinoxylans (AX) from wheat and rye, on the lipolysis of p-nitrophenyl laurate (p-NP laurate). p-NP laurate emulsions were prepared in the presence of increasing concentrations of SDFs (0.1%, 1.0% and 1.5% w/v), and lipolysis of emulsions by pancreatic lipase, particle size distribution of the p-NP laurate droplets, and viscosity of emulsions with soluble dietary fibres were measured. It was found that with increasing viscosity of SDFs, the rate of lipolysis decreased while the initial droplet size of the emulsion increased. Rate coefficients were more consistently correlated with average droplet size than with viscosity, suggesting that SDFs inhibited lipolysis primarily by increasing the size of droplets through flocculation, thereby decreasing the available surface area for lipase action.
Publisher: Elsevier BV
Date: 02-2024
Publisher: Wiley
Date: 19-01-2016
Abstract: Soluble dietary fibres have shown to have lipid reducing properties. However, their mechanisms of action are still unclear. The present study investigated how a soluble wheat arabinoxylan-rich fraction (AXRF) fed to pigs used as a human model reduced blood triglycerides. After 4 weeks on the experimental diets, blood from the jugular (JV) and hepatic portal (HPV) veins, bile from the gall bladder, and digesta s les from four sites of the small intestine (SI) and cecum were collected. The results showed that the AXRF significantly decreased the concentrations of total bile acid (BA) in the HPV (p < 0.01), JV (p < 0.01), bile (p < 0.05) and SI (p < 0.05), but with no effect on ileal BAs excretion flux. Furthermore, blood triglyceride (TAG) levels were also lower with AXRF (p < 0.01) but with no significant effects on LDL-, HDL- or total cholesterol levels. The lower plasma TAG concentration was consistent with the reduced/delayed digestion and absorption of TAG with the AXRF (total fatty acid and MUFA p < 0.01 unsaturated fatty acid p < 0.05). The results suggest that AXRF reduced the levels of circulating BAs which slowed down the digestion of TAG and absorption of free fatty acids, with consequent reduction in blood TAG. Reduction in circulating bile acids by arabinoxylan causes reduction in lipids digestion and absorption.
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.FOODCHEM.2015.10.104
Abstract: Two main classes of interaction between soluble dietary fibres (SDFs), such as (1,3:1,4)-β-D-glucan (βG) and arabinoxylan (AX) and bile salt (BS) or diluted porcine bile, were identified by (13)C NMR and small angle X-ray scattering (SAXS). Small chemical shift differences of BS NMR resonances were consistent with effective local concentration or dilution of BS micelles mostly by βG, suggesting dynamic interactions whilst the reduced line widths/intensities observed were mostly caused by wheat AX and the highest molecular size and concentrations of βG. SAXS showed evidence of changes in βG but not AX in the presence of BS micelles, at >13 nm length scale consistent with molecular level interactions. Thus intermolecular interactions between SDF and BS depend on both SDF source and its molecular weight and may occur alone or in combination.
Publisher: Elsevier BV
Date: 11-2010
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0FO00080A
Abstract: A number of studies have shown a positive relationship between diets rich in soluble dietary fibres (SDF) such as β-glucan, pectin, guar gum and psyllium, and reduced serum cholesterol and thus a decreased risk of cardiovascular disease (CVD). Three major biological mechanisms have been proposed to explain the cholesterol-reducing effects of SDF: prevention of bile salt (BS) re-absorption from the small intestine leading to an excess faecal BS excretion reduced glycemic response leading to lower insulin stimulation of hepatic cholesterol synthesis and physiological effects of fermentation products of SDF, mainly propionate. Evidence for the latter mechanism is inconclusive, whereas in vivo, ex vivo and in vitro experiments suggest that BS micelles "bind" to SDF preventing their re-absorption. Whereas, glycemic responses to SDF have been studied extensively, the nature of interactions between bile salt micelles and SDF that lead to incomplete BS re-absorption are poorly defined. Three potential physicochemical mechanisms are proposed together with suggestions for in vitro experiments to test them.
No related grants have been discovered for Purnima Gunness.