Glyn O. Phillips
Hubei University of Technology
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Featured researches published by Glyn O. Phillips.
Archive | 2011
Syed K.H. Gulrez; Saphwan Al-Assaf; Glyn O. Phillips
The terms gels and hydrogels are used interchangeably by food and biomaterials scientists to describe polymeric cross-linked network structures. Gels are defined as a substantially dilute cross-linked system, and are categorised principally as weak or strong depending on their flow behaviour in steady-state (Ferry, 1980). Edible gels are used widely in the food industry and mainly refer to gelling polysaccharides (i.e. hydrocolloids) (Phillips & Williams, 2000). The term hydrogel describes three-dimensional network structures obtained from a class of synthetic and/or natural polymers which can absorb and retain significant amount of water (Rosiak & Yoshii, 1999). The hydrogel structure is created by the hydrophilic groups or domains present in a polymeric network upon the hydration in an aqueous environment. This chapter reviews the preparation methods of hydrogels from hydrophilic polymers of synthetic and natural origin with emphasis on water soluble natural biopolymers (hydrocolloids). Recent advances in radiation cross-linking methods for the preparation of hydrogel are particularly addressed. Additionally, methods to characterise these hydrogels and their proposed applications are also reviewed.
International Journal of Biological Macromolecules | 2014
Huiling Kong; Jixin Yang; Yifeng Zhang; Yapeng Fang; Katsuyoshi Nishinari; Glyn O. Phillips
Selenium nanoparticles (SeNPs) were prepared by using gum arabic (GA) as the stabilizer in a facile synthetic approach. The size, morphology, stability and antioxidant activity in vitro of the gum arabic-selenium nanocomposites (GA-SeNPs) were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and ultraviolet-visible spectrophotometry (UV-vis). SeNPs (particle size of ∼34.9 nm) can be stabilized in gum arabic aqueous solutions for approximately 30 days. FTIR results show that SeNPs were combined to the hydroxyl groups of GA. In the present work, the alkali-hydrolyzed GA (AHGA) was also prepared and its efficiency in stabilizing SeNPs was compared with GA. It was concluded that the branched structure of GA was a significant factor for the functionality. The hydroxyl radical scavenging ability and DPPH scavenging ability of GA-SeNPs were higher than those of AHGA-SeNPs and could reach 85.3±2.6%, 85.3±1.9% at a concentration of 4 mg/ml, respectively.
Journal of Colloid and Interface Science | 2012
Xiangyang Li; Yapeng Fang; Saphwan Al-Assaf; Glyn O. Phillips; Fatang Jiang
In a previous study (Langmuir 28 (2012) 10164-10176.), we investigated the complexation of bovine serum albumin (BSA) with sugar beet pectin (SBP). A pH-composition phase diagram was established and structural transitions in relation to the phase diagram during complexation were identified. The present study examines the implications of these interactions on the emulsifying performance of BSA/SBP mixtures. Middle-chain triglycerides (MCTs) in water emulsions were prepared using conditions corresponding to different regions of the phase diagram. At high pHs and in the stable region of mixed individual soluble polymers where complexation is absent, there is no improved emulsifying performance, compared with the individual protein and polysaccharide. For these mixtures, the emulsion characteristics are controlled by the major component in the solutions, as determined by the competitive adsorption of the two components at the oil-water interface. At low pHs and low BSA/SBP ratios, and so mainly within the stable region of intramolecular soluble complexes, BSA/SBP mixtures greatly improve the stability of emulsions. Here, stabilisation is controlled by the cooperative adsorption of the two components at the oil-water interface. Through electrostatic complexation BSA promotes the adsorption of SBP on to interfaces to form a thick steric layer around emulsion droplets and thus providing better stability. At low pHs and high BSA/SBP ratios, that is, mainly within the unstable region of intermolecular insoluble complexes, emulsions prepared are extremely unstable due to bridging flocculation between emulsion droplets.
International Journal of Biological Macromolecules | 2000
Saphwan Al-Assaf; J. Meadows; Glyn O. Phillips; Peter A. Williams; B.J. Parsons
Shear flow, dynamic oscillation and extensional viscosity measurements were used to compare the rheological performance of several hylan samples (M(v) 1.6, 3.2, 3.7, 4.7 and 5.6x10(6)) and hyaluronan (M(v) 1.4 and 1.8x10(6)) before and after hydroxyl radicals (*OH) induced degradation. It was found that the higher molecular weight cross-linked structure of hylan was more resistant to degradation than hyaluronan and that this superior stability was reflected in various rheological parameters. The *OH degradation of the initial hylan and hyaluronan samples produced a range of polysaccharides based on hylan and hyaluronan with molecular weight covering a range from 0.5-5.6x10(6). The rheological parameters associated with the polysaccharides could then also be studied. Zero shear values of the complex viscosity (eta*), dynamic viscosity (eta) and shear viscosity (eta) were calculated using the method of Morris(1) and shown to approach the same value at zero shear or frequency. An adaptation of the method of Gibbs et al. gave a master curve for the storage and loss modulus of hyaluronan and hylan, which encompasses a 10-fold molecular weight and a 5-fold concentration variation. In all instances for hylan, the storage modulus predominates over the loss modulus, whereas for hyaluronan, the reverse is true, demonstrating the greater elasticity of hylan throughout the whole experimental range of molecular weights and concentrations.
Archive | 2005
John F. Kennedy; Glyn O. Phillips; Peter A. Williams
Part 1 Standards for tissue banks and for radiation sterilisation of tissues. Part 2 Methodology in the sterilisation and preservation of tissues. Part 3 Effect of radiation on bone, tissues and their components. Part 4 Viral aspects of tissue for transplantation. Part 5 Microbiological aspects of tissue for transplantation.
Carbohydrate Polymers | 2013
Peng Mao; Meng Zhao; Fan Zhang; Yapeng Fang; Glyn O. Phillips; Katsuyoshi Nishinari; Fatang Jiang
This paper investigates the phase separation and phase separation-induced fractionation of gum arabic (GA)/sugar beet pectin (SBP) mixed solutions. A phase diagram, including cloud and binodal curves, was established by visual observation and phase composition analysis. The deviation of the binodal curve from the cloud curve was a result of phase separation-induced fractionation of polydisperse GA and SBP molecules. Fractionation of GA increased the content of arabinogalactan-protein complex (AGP) from ca. 13% to 27%. The fractionated GA (FGA) showed improved emulsifying functionality, whereas the fractionated SBP (FSBP) had a reduced emulsifying functionality. The changes in emulsifying efficiency can be explained by interfacial adsorption behaviors at the oil-water interface as indicated by interfacial tension measurements.
Proceedings of the Nutrition Society | 2003
Saphwan Al-Assaf; Glyn O. Phillips; Peter A. Williams; Shoji Takigami; Peter W. Dettmar; Michael E. Havler
Molecular variables, using aqueous and alkaline extracts, of the polysaccharide from ispaghula husk (IH) were examined using gel-permeation chromatography linked to multi-angle laser light scattering. Progressive extraction can yield a component with a molecular weight (MW)value up to about 7 x 106 Da, and gels, which accompany the extraction, have MW ranging from 10-20 x 106 Da. To mimic the polysaccharide degradation, particularly in the colon, the solid IH was degraded progressively using ionising radiation. A chain break occurs every 7.5 kGy in NaOH and every 15 kGy in water. The solid-state matrix is opened by the radiation to yield increased visco-elasticity of the aqueous extracts at critical radiation doses, before further degradation occurs after about 12 kGy. Differential scanning calorimetry is used to study the mechanism of interaction of water with IH. The first water to be taken up is non-freezing water and represents about twelve water molecules/disaccharide unit of the polysaccharide. As the water content is increased, the water becomes bound to the polysaccharide and freezes and melts at a temperature different from free water. This water is thermodynamically distinguishable from free water. It forms amorphous ice on cooling which crystallises exothermically and subsequently melts endothermically. Saturation occurs at a water content of 2-3 g water/g polymer, showing that about 60% of the water in the system is bound. The most surprising conclusion is that despite the fact that the IH swells in water to form a solid and stiff gel, the greater part of that water in the gel is still free and behaves like liquid water.
Hyaluronan#R##N#Proceedings of an International Meeting, September 2000, North East Wales Institute, UK | 2002
Michel Milas; Marguerite Rinaudo; I. Roure; Saphwan Al-Assaf; Glyn O. Phillips; Peter A. Williams
ABSTRACT Rheological properties of hyaluronan solutions are related not only to the molecular weight or concentration, but also to the origin of the samples. Here we present a comparative rheological study of hyaluronan, in aqueous solutions, from bacterial and animal sources with a cross-linked hyaluronan (hylan). Using a variety of rheological techniques, the behaviour of hyaluronan (Mw 0.8 − 2.2 × 106), crosslinked hyaluronan (hylan) (Mw 1.8 − 12.5 × 106) and Healon (Mw ˜ 5 × 106) (a proprietary hyaluronan) was studied over a large range of molecular weights. The object was to study the effect of the cross-links in hylan on the various rheological parameters, in comparison with linear hyaluronan. There are significant differences. The Huggins constant and the critical overlap parameter C*[η] are considerably lower for hylan and an increase in moduli at low frequencies was observed for hylan compared with the hyaluronan samples at all molecular weights studied. The results point to a difference in structure in dilute solution for hylan due to the ability to form networks, which can be removed by pressure filtration. In contrast, we do not find an increase of the steady shear viscosity and elastic modulus at higher concentrations when a homogeneous entangled network is reached. In the semi-dilute regime, the Newtonian viscosity scales as C4.1 to C3.6 by increasing the polymer concentration. The critical shear rate and the cross-over frequency (ωρ) vary as C-2 M-3. The plateau modulus G ∼ G0 scales as C2.15. We attribute this behaviour, which agrees well with the de Gennes prediction in a good solvent, to the semi-rigid character of the hyaluronan chain and to the predominance of entanglements over the cross-link points present in hylan in the semi-dilute domain. Due to the higher apparent molecular weights which are possible with hylan structures but not with the hyaluronans currently available, a wider range of applications can be achieved with hylans when viscoelasticity is required, particularly for the viscosupplementation of synovial fluid damaged by osteoarthritis.
RSC Advances | 2016
Xiaolin Yao; Shengping Xiang; Ke Nie; Zhiming Gao; Weiqi Zhang; Yapeng Fang; Katsuyoshi Nishinari; Glyn O. Phillips; Fatang Jiang
Protein/polysaccharide electrostatic complexes have been widely used in food products to confer structure and stability. Intramolecular soluble complexes (ISCs) have superior emulsifying properties in stabilizing oil-in-water (o/w) emulsions. This paper investigates the potential application of ISCs to stabilize polyunsaturated fatty acids that were difficult to disperse and liable to oxidation. The idea was demonstrated using whey protein isolate/gum arabic (WPI/GA) ISCs and conjugated linoleic acid (CLA). Zeta potential measurements indicated a stoichiometry of r = 1.0 for the electrostatic complexation of WPI/GA. Excess of GA (r 20 mM and therefore seriously reduced the stability of ISCs-stabilized CLA emulsions. The superiority of ISCs in stabilizing polyunsaturated fatty acids is due to the cooperative adsorption of protein and polysaccharide at the emulsion interface, providing strong steric and electrostatic effects against droplet aggregation and coalescence and thus excellent physical stability. The improved oxidative stability should arise from the free radical scavenging ability of the protein at the emulsion interface, reducing lipid oxidation.
Food Biophysics | 2015
Meng Zhao; Fangning Qu; Sha Cai; Yapeng Fang; Katsuyoshi Nishinari; Glyn O. Phillips; Fatang Jiang
Correlation between lactic acid bacteria (LAB) survivability and physical properties of microcapsules is critical to revealing the protecting mechanism of microcapsules for LAB. In this paper, five formulae of microcapsules with increasing mechanical strength were chosen to encapsulate Lactobacillus acidophilus CGMCC1.2686 using the method of emulsification/internal gelation. Morphological and size characteristics showed that particle diameter of the five LAB microcapsules ranged from 263.4 to 404.6xa0μm, with a span factor from 0.87 to 1.12. The increased mechanical strength of the microcapsules was accompanied with increased viscoelasticity and structural compactness as observed by scanning electron microscopy. Most of the microspheres shrinked in simulated gastric juice (SGJ), whilst swelling in bile salts solution (BS). Regression analysis showed that cell viability in SGJ was positively correlated with the mechanical strength of microcapsules. However, increasing mechanical strength did not significantly improve cell survival in BS.