Flow Behavior of Sweet Potato Starch in Mixed Sugar Systems

  • Cho, Sun-A (Department of Food Science and Technology, Dongguk University) ;
  • Kim, Bae-Young (Department of Food Science and Technology, Dongguk University) ;
  • Yoo, Byoung-Seung (Department of Food Science and Technology, Dongguk University)
  • Published : 2008.09.30


Flow behaviors of sweet potato starch (SPS) pastes (5% w/w) were studied in the presence of various sugars (xylose, glucose, fructose and sucrose) and sugar alcohols (xylitol and sorbitol). The flow properties of SPS-sugar mixtures were determined from the rheological parameters of power law model. The vane method was also employed for determining yield stresses of SPS-sugar mixtures directly under a controlled low shear rate. At $25^{\circ}C$ all the samples showed shear-thinning behaviors ($n=0.35{\sim}0.44$) with yield stress. The consistency index (K) values of SPS-sugar mixtures increased in the following order: sorbitol> xylitol> control (no sugar)> sucrose> fructose> glucose> xylose, showing that the addition of sugar alcohols enhanced the K values. The yield stress values were reduced in the presence of ugars and sugar alcohols and they also increased with an increase in swelling power of starch granules in the SPS-sugar mixture systems.


sweet potato starch;sugar;flow behavior;viscosity;vane yield stress


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