1. Rheology in Daily Life: The Orbitz Drink
Jason Hower
Corvallis High School
Dr. Skip Rochefort
Chemical Engineering Dept.
Oregon State University
Acknowledgements
NYPRO Oregon
NutraSweet KELCO Company

2. Belly up for a pop of free-floating globules
Belly up for a pop of free-floating globules! How ‘bout those new sodas with the colored gelatinous blobs in them?
Clearly Canadian, maker of transparent fruit-flavored
drinks, has a new idea: Orbitz
Looking like a Perrier with measles, it mingles the trade-
mark soft drink with floating globules of colored fruit gel.
Orbitz went on sale Feb. 13 in Oregon and is available in
27 states. An estimated 300 million US pop drinkers can
choose from four flavors: raspberry/citrus, vanilla/orange,
blueberry/melon/strawberry, pineapple/banana/cherry/
coconut. The globules seem relatively tasteless and feel like
the pulp that defines “real” orange juice.
The drink works because the carbohydrate gel spheres
are roughly the same specific gravity as the surrounding
liquid.
One way to make them sink? Add a little alcohol and
the colored gel sinks to the bottom.
- Oregonian Newspaper (1997)
INGREDIENTS: Water, High Fructose
Corn Syrup, Sugar, Sodium Citrate,
Citric Acid, Natural Flavor, Gellan Gum,
Xanthan Gum, color added
Orbitz Beads: Gellan Gum
Orbitz Fluid: Water, Corn Syrup, Xanthan Gum

3. Claims made by Oregonian Article
The Orbitz gel beads are ”roughly the same specific gravity as the surrounding fluid.” This is the reason they float.
“Add a little alcohol and the colored gel sinks to the bottom.”

4. Goals
To determine if the explanation given by the Oregonian is corrupt or if there is another explanation for the gel beads staying suspended.
To test the claim that when alcohol is added to Orbitz, the gel beads sink to the bottom of the drink.
To replicate the drink and its properties

5. Fluid Density and Bead Behavior
Measured density of Orbitz fluid
Performed panel taste tests to arrive at an approximate sugar concentration
Made solutions of water, karo syrup and XG to match the density of Orbitz fluid.
Placed Orbitz gel beads in solutions to test behavior

7. Viscosity Background Viscosity is a fluid property
Defined as Resistance to flow
Bohlin Constant Stress Rheometer (Model CS-50)
Couette geometry (Cup and Bob)

8. Couette Geometry Cup and Bob geometry Rotated to maintain shear stress
Shear stress measured between the bob and cup wall

9. Viscosity Background Viscosity = shear stress/shear rate
Shear Stress(Pa) is the stress put on the fluid
Shear rate(1/s) is proportional to the bob rotation rate
Bohlin Rheometer measures shear rate and shear stress and calculates Shear Viscosity (Pa-s)
Water viscosity = 1.0E-3 Pa-s(1.0 mPa-s)

10. Fluid Behaviors
Newtonian fluid: constant viscosity with increasing shear stress
Shear Thinning fluid: decreasing viscosity with increasing shear stress
Bingham fluid: possesses a yield stress

11. Study of Orbitz Viscosity
Bohlin Constant Stress Rheometer (CS-50)
Orbitz is shear thinning, Bingham fluid (yield stress)

12. Xanthan Gum
Xanthan gum(XG) is a high molecular weight polymer produced in a bacterial fermentation
XG used in many food applications as a thickening and suspending agent

13. Orbitz Replica Attempts
Compared Orbitz viscosity to xanthan gum solutions
Made xanthan gum, Karo syrup and water solutions
Measured viscosity with Bohlin Rheometer

14. Orbitz Replica Attempts
750ppm XG + 12% KS matched high shear viscosity
Unable to obtain Yield Stress

15. When Alcohol is Added
Oregonian article claimed that adding alcohol would make beads sink
Added equivalent of one shot of 90 proof alcohol per bottle
Orbitz drink final concentration = 4.5vol% alcohol

16. When Alcohol is Added Orbitz + 4.5% Ethanol: Density= 1.019 g/mL
Gel Beads remain suspended (indefinitely)

17. Conclusions
Oregonian’s explanation for gel bead behavior (neutral buoyancy) is incorrect.
Gel beads are suspended because Orbitz drink is a viscous fluid with a yield stress. Due to addition of xanthan gum.
Oregonian’s claim that the addition of alcohol will cause the beads to sink is incorrect.

18. Future Work Make Orbitz beads from Gellan gum
Replicate Orbitz fluid properties
Find way to create a yield stress in xanthan solutions