Emulsions: Principles and preparation - Questions

8 important questions on Emulsions: Principles and preparation - Questions

Surfactants generally adsorb at oil-water interfaces faster than proteins. T/F

True

Membrane emulsification produces larger throughputs than conventional agitation techniques for emulsification. T/F

False

The ageing step in ice cream processing is important because
  • It allows enough time for proteins to absorb at the oil-water interface
  • It allows small ice crystals to form
  • It allows enough time for proteins to adsorb at the air-water interface
  • It allows enough time for low molecular weight emulsifiers to adsorb at the oil-water interface

It allows enough time for low molecular weight emulsifiers to adsorb at the oil-water interface
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In emulsions, flocculation:
  • May precede droplet coalescence
  • Can decrease the effective dispersed phase volume fraction
  • Is associated with the rupture of the interfacial film between two associated droplets
  • Is generally encountered in emulsions with a high net surface charge of the droplets

May precede droplet coalescence

Which of the following emulsifiers would you select to prepare a water-in-oil emulsion:
  • Sodium caseinate
  • Sodium stearoyl lactylate (anionic surfactant, HLB ~ 20)
  • Polysorbate 20 (non-ionic surfactant, HLB ~ 16)
  • PGPR (non-ionic surfactant, HLB ~ 3)

PGPR (non-ionic surfactant, HLB ~ 3)

Emulsification using a high pressure homogeniser:
  • Can produce highly mono disperse emulsion droplets
  • Does not require multiple passes
  • Is suitable for producing small emulsion droplets
  • Is adapted when the product contains shear- and temperature-sensitive ingredients

Is suitable for producing small emulsion droplets.

What does the HLB of surfactants mean for dissolving oil or water?

Surfactants with a low HLB dissolve oil. Surfactants with a high HLB dissolve in water.

If we would plot the strength of droplet-droplet repulsive interactions in an oil-in-water emulsion as a function of the dispersed phase volume fraction (graph below), milk would be located:

In area 1

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