Physical Properties of Starch

1
Physical Properties of Starch
2
Considerations

• Five properties to consider when choosing a
  starch for food preparation
• Retrogradation
• Viscosity
• Stability
• Opacity vs. Translucency
• Texture

3
Retrogradation

• Firming of a gel during cooling and standing
• Amylose-amylose bonding
• Desirable when forming a gel
• Undesirable when gel cracks upon standing
• Cracks in a custard pie
• Effect of acids
• Breaks down starches and weaken gels.
• Should be added to a starch mixture after it has
  thickened.

4
Retrogradation

• Syneresis
• Water leaking from a gel due to prolonged
  storage.

5
Viscosity

• Resistance of a mixture to flow
• Starches hold their shape, resist flow
• Example -- flow of water vs. starch paste
• More starch, greater resistance to flow
• Amylose vs. amylopectin

6
Stability

• The ability of a thickened mixture to remain
  constant over time and temperature changes
• Freezing
• Heating
• Waxy maize starch
• Flour
• Cornstarch

7
Opacity vs. Translucency

• Opacity
• How much an object blocks light
• Wheat starch
• Good for sauces and soups
• Translucency
• How much light can pass through an object
• Cornstarch, potato starch, arrowroot
• Good for fruit sauces, pie fillings, glazes

8
Texture

• Consider type of starch
• Gritty vs. smooth texture
• Mouthfeel