Publication no. C-2001-1204-01R |  VIEW ARTICLE

Steady and Dynamic Shear Rheological Properties of Starch and Decolorized Hsian-tsao Leaf Gum Composite Systems.

Lih-Shiuh Lai (1,2) and Chih-Lun Liao (1). (1) Department of Food and Nutrition, Providence University, 200 Chungchi Rd., Shalu, Taichung 433, Taiwan, ROC. (2) Corresponding author. E-mail: <lslai@pu.edu.tw> Phone: 886-4-26328001, Ext. 5301. Fax: 886-4-26318407. Cereal Chem. 79(1):58-63. Accepted September 26, 2001. Copyright 2002 American Association of Cereal Chemists, Inc.

Rapid Visco Analyser (RVA) and dynamic rheological measurements were performed on a mixture of decolorized hsian-tsao leaf gum (dHG) and starch as a function of starch-to-gum ratio (S/G 0:6, 1:5, 2:4, 3:3, 4:2, 5:1, and 6:0), starch type (wheat, corn, and tapioca), and total solid content (2, 3, and 4%). Under S/G of 5:1, 4:2 and 3:3, dHG interacted with starch synergistically, which resulted in a marked increase in viscosity during cooling. The storage modulus of the resulting mixed gel was higher than the loss modulus, and both moduli were almost frequency-independent throughout the frequency range tested, indicating that the composite gels could be classified rheologically as elastic gels. Mixed systems with tapioca starch showed higher pseudo-gel viscosity in the RVA test, but lower storage modulus in the dynamic test than those with wheat or corn starch. Such results implied that tapioca starch contributed a more viscous property but wheat and corn starch contributed a more elastic property to the mixed systems.