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Introduction - Foam of industrial protein preparations

Q: Does a LMW surfactant give a good foam ability and foam stability?

Ability yes, because the molecules are small they have a very high adsorption rate. Stability no, because their elastic modulus is low (10-20 mN/m) and their is a low hydrophobicity (no aggregation).

Q: Do particles give a good foam ability and foam stability?

Ability no, because the particles are large they have a very low adsorption rate. Stability yes, because of pickering (steric) stabilisation and a very high (infinity) elastic modulus.

Q: What is the effect on adding a surfactant to a protein on the foam stability?

It depends on the pH. A BLG protein at pH 7 does not benefit from a surfactant (the stability is only lower), at pH 3 the stability does increase with addition of a surfactant.

Q: What is the influence of centrifugation/filtration on the foam ability and stability?

Centrifugation (remove larger particles) results in a small improvement of the quality. Microfiltration (remove small particles) results in a very large increase in foam ability and stability.

Q: Why is the foam stability in a heated lysozyme higher than in untreated lysozyme?

Because of the hydrophobicity, the hydrophobic groups are more exposed, it absorbs fasters to the air/water interface and results in a higher foam ability and stability.

6 important questions on Introduction - Foam of industrial protein preparations

What are 3 surfactants with their molecular weight and size?

LMW surfactants, 200-1200 Da, <2 nm
Proteins, 10 kDa - 700 kDa, 2-10 nm
Particles, 1-500 um

Does a LMW surfactant give a good foam ability and foam stability?

Ability yes, because the molecules are small they have a very high adsorption rate. Stability no, because their elastic modulus is low (10-20 mN/m) and their is a low hydrophobicity (no aggregation).

Do particles give a good foam ability and foam stability?

Ability no, because the particles are large they have a very low adsorption rate. Stability yes, because of pickering (steric) stabilisation and a very high (infinity) elastic modulus.

What is the effect on adding a surfactant to a protein on the foam stability?

It depends on the pH. A BLG protein at pH 7 does not benefit from a surfactant (the stability is only lower), at pH 3 the stability does increase with addition of a surfactant.

What is the influence of centrifugation/filtration on the foam ability and stability?

Centrifugation (remove larger particles) results in a small improvement of the quality. Microfiltration (remove small particles) results in a very large increase in foam ability and stability.

Why is the foam stability in a heated lysozyme higher than in untreated lysozyme?

Because of the hydrophobicity, the hydrophobic groups are more exposed, it absorbs fasters to the air/water interface and results in a higher foam ability and stability.

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