Surface active material Flashcards
What is a surface active material ?
Are molecules that contain both hydrophilic side an hydrophobic side.
Surface active material: 1. Fatty acids
Small molecules, they have a small hydrophilic(they often sit more in the oil** ) part due to the carboxyl group. And they have a hydrophobic part which can vary in length. They cam adsorb ant oil water interfaces.
**They are not really suitable to stabilize the interfaces
Surface active material: 2. Surfactants(esters)
The size of the hydrophilic groups can be altered.
Surface active material: 3. Proteins: globular proteins
Large molecules, they have a core that is hydrophobic and outside is more hydrophilic. To be one part and the other in oil and water, is necessary to have large distinct hydrophobic and hydrophilic areas. To do this the proteins may slightly unfolded.
**Very suitable for making emulsions
With hydrolysis –>smaller molecules–>not enough areas. (PEPTIDES)
E.g: whey proteins, B-lactoglobulin, lysozyme, ovalbumin, etc.
Surface active material: 3.Felxible proteins
Examples: caseins, caseinates, gelatin.
Linera chain of peptides without secondary structure. This proteins contain both hydrophilic groups and hydrophobic groups, as they are very flexible they can easily rearranged at the interface.
Surface active material: 5. Polymers (macromolecules)
Only chemically block co-polymers can be found, which are used a lot in pharmaceutical industry. Not any in nature, too hydrophilic !!!So you have to modified polysaccharides.
Surface active material: 5. Polysaccharide (gum arabic)
One exception of one polysaccharide, the surface is active by nature. It has a carbohydrate group(attached to the backbone) and a protein group (backbone–>some hydrophobic areas). The proteins are surface active, the carbohydrate parts are mostly hydrophilic and will be present mostly in aqueous phase.
