Behavioral Objectives

          Chapter 5

          Purdue griffin

          1. Define or identify:

          • viscoelastic
          • yield stress (yield value)
          • pseudoplastic flow
          • Newtonian flow
          • thixotropic flow
          • hystersis
          • viscosity
          • short flow
          • long flow
          • junction zone
          2. Describe and give a molecular explanation of the effects of the following on polysaccharide solution viscosity:
          • chemical structure
          • molecular shape
          • temperature
          • concentration
          • pH
          • ionic strength*
          • concentration of solutes*
          * Explain why these factors increase the viscosity of some polysaccharide dispersions and decrease the viscosity of others.

          3. Describe and compare the two general kinds of shear-thinning rheologies.

          4. Describe, with examples of applications, how use can be made of pseudoplastic rheology in processing and formulating products.

          5. Discuss the molecular basis for pseudoplasticity and thixotropy.

          6. Discuss the effects of concentration and molecular weight on pseudoplasticity.

          7. Describe and discuss the relationship of pseudoplasticity to mouthfeel.

          8. Describe the molecular basis for a yield value (yield stress).

          9. Discuss how polysaccharides that produce solutions with yield values can be applied, using examples. Identify applications of yield value.

          10. Describe the molecular bases for gel formation.

          11. List and describe the 5 types of junction zones related to food gum use.

          12. Given the structure of a polysaccharide, predict the properties of that polysaccharide. Such properties should include (a) solubility, (b) viscosity, (c) the effect of pH on viscosity and solubility, and/or (d) the effect of salts on viscosity.
           


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