2 results for Pinder, DN

  • Effect of high-pressure treatment on normal rice and waxy rice starch-in-water suspensions

    Oh, HE; Hemar, Yacine; Anema, SG; Wong, M; Pinder, DN (2008-07-19)

    Journal article
    The University of Auckland Library

    The effects of treatment pressure (???700 MPa), temperature at treatment (10???60 ??C), and treatment duration (0???30 min) on the gelatinization of normal and waxy rice starches were investigated. Pressure-treated starch suspensions were examined for pasting behaviour, initial apparent viscosity (??initial), degree of swelling, birefringence changes, and leaching of starch and amylose. The ??initial measurements provided an objective and analytical means of determining the degree of pressure-induced gelatinization of starch. Both normal and waxy rice starches exhibited sigmoidal-shaped pressure-induced gelatinization curves. The degree of gelatinization was dependent on the type of starch, the pressure, the temperature, and the duration of treatment. Different combinations of these factors could result in the same degree of gelatinization. There was a linear correlation between the degree of swelling and ??initial. After treatments at ???500 MPa, both starches lost all birefringence although they experienced different extents of change in ??initial and the degree of swelling.

    View record details
  • DWS microrheology of a linear polysaccharide.

    Hemar, Yacine; Pinder, DN (2006-03)

    Journal article
    The University of Auckland Library

    Diffusing wave spectroscopy has been used to measure the rheological behavior of pullulan (Mw = 1 ?? 10^{5}) aqueous solutions up to concentration of 40 g/dL. It was found that these solutions were mainly viscous, with the loss modulus G?????? higher than the elastic modulus G???. The plot of the specific viscosity ??sp as a function of pullulan concentration showed two critical concentrations c* = 4 g/dL and c** = 15 g/dL. For c < c*, ?? sp ??? c^{1.25??0.05}; for c* < c < c**, ?? sp ??? ^{c2??0.05}; and for c > c**, ?? sp ??? c^{4.5??0.5}. These results are in very good agreement with those reported in the literature.

    View record details