18A-8

J. HIGIRO¹, T. J. Herald¹, and S. Alavi². (1) Food Science Institute, Kansas State Univ., 203 Call Hall, Manhattan, KS 66596, (2) Dept. of Grain Science & Industry, Kansas State Univ., 53 Waters Hall, Manhattan, KS 66506

Gum applications use continues to expand. The beverage industry has experienced growth, with gums having a significant contribution to mouthfeel and emulsion stability. Notably, gums have exhibited their gel strength singly or in combination with proteins and starches as described in the literature. Although the same amount of literature does not exist as with gel systems in hypothesizing the mechanism in which gum disperse and interact in dilute solutions. Our objective was to use oscillatory rheological techniques to describe the visco-elastic behavior of xanthan and locust bean gum (LBG) in dilute solution. Xanthan and LBG solutions were dialyzed against deionized distilled water for 72 hr and blends of 0.025% (m/v) prepared. Final concentrations were validated using the phenolic-sulfuric acid test. Gums were evaluated for intrinsic viscosity and elastic component. Molecular conformation of the complex xanthan-LBG was assessed by: 1) the power law equation çsp=aCb where çsp is the specific viscosity, C the gum concentration, a and b the power law coefficients 2) the coefficients Km and á from the model derived from the Huggins equation. Results showed a significant increase of the intrinsic viscosity up to an optimum value of 306.61 dl/g with 60% xanthan and 40% LBG. The coefficient Km for that blend was positive, and á the highest, indicating the strongest attraction. The coefficient b was 0.79 for xanthan and 1.23 for LBG, which agreed with the suggested rod-like and random coil structures, respectively. The same coefficient increased with the increase of LBG in the blend, suggesting a more flexible xanthan-LBG complex. The elastic component was higher than the viscous component in most blends. Xanthan and LBG exhibited unique rheological behavior in dilute solution. Their interaction may be monitored using oscillatory rheological methods. The results may be used by product developers and engineers in designing or improving new or existing beverages.

Session 18A, Carbohydrate: General
2:00 PM - 5:30 PM, Sunday PM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana