Foam of industrial protein preparations

Question 1

Different types of surfactants:

Answer 1

1. LMW: 200-1200Da, fatty acids, sucrose-monoesters, SDS, <2nm
2. Proteins: 10lDa-700kDa,ovalbumin, B-lactoglobulin, lysozyme. 2-10 nm
3. Particles: , protein aggregates (glass, latex). 1-500 micrómetro.

Question 2

Surfactant mechanisms and properties: for foam ability and foam stability for the different types of surfactants.

Answer 2

LMW (SDS): high foam ability and low foam stability
Proteins (Whey proteins): Low-high foam ability and Low-high foam stability.
Particles (Aggregates): Foam ability very low and very high foam stabilility.
Foam stability Low
(s-min)

Question 2

Surfactant mechanisms and properties: for foam ability and foam stability for the different types of surfactants.

Answer 2

• LMW (SDS): high foam ability (very high adsorption rate) and low foam stability
• Proteins (Whey proteins): Low-high foam ability and Low-high foam stability.
• Particles (Aggregates): Foam ability (make a foam) very low(very slow adsorption rate) and very high foam stability.

Question 3

Foam ability is not related to foam stability. TRUE OR FALSE

Answer 3

TRUE

Question 4

Foam stability: effects of surfactants

Answer 4

Expressing it as a foam half-life time. There is a debile area and the the surfactant dominated regime. Surfactant–>SDS.

Question 5

Varation in foam properties of WPC: surfactants they do not always dissolve very well. Gráfica ejercicios.
Where this come from?

Answer 5

We see that the overrun or the foam ability, for three samples is quite good but for four samples we do not have any foam at all. Even with similar gross composition, some samples make foam, others do.
Where this come from? If we look to powders and dissolve and mix them with water, not all the material dissolves not all molecules go to the solution as a free molecule. Some particles remain, larger particles and smaller particles. Remove the larger particles by centrifugation and smaller particles by microfiltration.

Question 6

Effect of the powder properties in the foam. The presence of non-dissolved particles.

Answer 6

Microfiltration results in a very large increase in foam stability and foam ability. In commercial protein preparations not all protein is ‘dissolved’

Question 7

Foam: effect of protein heat treatment. Lysozyme.

Answer 7

If you look to foam of lysozyme, native lysozyme we cannot make a foam under these conditions. If you do heat treatment to the lysozyme we suddenly get a very nice foam and it also quite stable. The longer i heat higher the stability and we do not create aggregates under this conditions the protein refolds.

Question 8

Look to the foam stability curve of heated lysozyme. Which changed molecular property is most likely the cause of the increased foam stability?
FIGURE 48.

Answer 8

The charge is not affected by heating. Since the protein has refolded, the size should be also constant. Therefore, most likely the refolded protein has an increased exposed hydrophobicity.