Emulsions, Foams and Gels Flashcards
Define emulsion
Emulsion refers to combining fat and water
Define foam
A foam is a substance that is formed by trapping many gas bubbles in a liquid or solid
Define gel
A gel is a sol in which the solid particles are meshed such that a rigid or semi-rigid mixture results. Cross-linking within the gel’s polymer or colloidal network causes a gel to behave as a solid in its steady-state and makes it feel tacky.
Example of an oil-in-water emulsion
Milk Hollandaise Mayonnaise Aioli Cream
Challenges with emulsification
Stability
- flocculation
- creaming
- coalescence
- Oswald ripening
Why is separation of emulsifications bad?
Causes food spoilage, which is less attractive to the consumer
How can we improve emulsification stability?
Adding a biopolymer, emulsifier, texture modifier, ripening inhibitor, and weighting agent
Name the properties of emulsifiers
Phospholipid
Polar and non polar groups form a monolayer
What is the role of an emulsifier?
To reduce surface tension
What are the properties of a ‘good emulsion’?
Good emulsifying capacity
Able to lower the interfacial tension in order to lessen the energy needed to produce particles
How do we assess emulsion stability?
Assess any changes in dispersion, changes on the droplet
Through centrifugation and heating
What factors does emulsion stability depend on?
Van de Waals interactions
Electrostatic repulsion
What are the properties of gels?
Not stable
Rigid
Elastic
Brittle
Where do carrageenan gels originate ?
seaweed
What are polysaccharides gels made from?
Trees, seeds, fruit
