Viscosity development during aqueous dispersion and dissolution: A comparison of PGX super( registered ) with other dietary supplements and individual polysaccharides

• Published in: Food hydrocolloids 2014-07, Vol.38, p.152-162
• Main Authors: Smith, Ian H, Lawson, Christopher J, Harding, Stephen E, Gahler, Roland J, Lyon, Michael R, Wood, Simon
• Format: Article
• Language: English
• Subjects: Dispersions; Dissolution; Emptying; Polysaccharides; Rheometers; Shear; Vanes; Viscosity
• ISSN: 0268-005X
• DOI: 10.1016/j.foodhyd.2013.12.004

Viscosity development with time was studied during the aqueous dissolution of the novel polysaccharide complex PGX super( registered ), a finer particle size version used in meal replacement PGX sub(f,) and a blend of the three polysaccharides 3PB used in their manufacture. Results were compared with those of single polysaccharides and other commercially available soluble-fibre supplements. Measurements were made at 25.0 degree C in a rheometer vane and cup system at similar to 1000 s super(-1). Samples suspended in low MW PEG were discharged from a syringe into water under shear in the measuring system. Final mixtures contained 0.5% w/w sample and 2% w/w PEG. Most samples reaching high final equilibrium/ultimate viscosities (12-138 mPa s), appeared to dissolve completely within 1 h but four samples required 1.5 to >14 h. PGX super( registered ), PGX sub(f) and 3PB gave the highest ultimate viscosities within timescales relevant to stomach emptying. Viscosity-time data were reasonably reproducible except those for xanthan gum. Distinct steps in viscosity development curves for 3PB and Biomed Type 2 were attributed to different dissolution rates of their component polysaccharides. For samples reaching final viscosities < 12 mPa s, dietary fibre products often left residues of insoluble material whilst single polysaccharides appeared to dissolve completely. Attempts at curve fitting the dissolution profiles to single-exponential or logarithmic models failed. Better representations were obtained using a two-component exponential model due to Kravtchenko, Renoir, Parker, and Brigand (1999) or a four-component extension of this model. Dissolution rates were also compared using time to reach 50 and 80% of the ultimate viscosity at full dissolution.