Competitive destabilization/stabilization of beta-lactoglobulin foam by PEO-PPO-PEO polymeric surfactants
2006 (English)In: Journal of Dispersion Science and Technology, ISSN 0193-2691, E-ISSN 1532-2351, Vol. 27, no 4, 527-536 p.Article in journal (Refereed) Published
The effect on ss-lactoglobulin foamability and foam stability of the poly(ethylene oxide)-poly(propylene oxide) block copolymers F127 (PEO99-PPO65-PEO99), molecular weight 12500 g/mol, and P85 (PEO26-PPO39-PEO26), molecular weight 4600 g/mol, has been investigated at constant protein concentration, 10 mu M (0.2 mg/L), and varying block copolymer concentrations, ranging from 0.02 to 1600 mu M. Foam was generated by means of air sparging and the foam volume and liquid volume of the foam were measured for one hour. It was found that foam stabilized by F127 or P85 in the concentration range 20-1600 mu M contained a larger liquid volume initially than pure ss-lactoglobulin foam. Furthermore, ss-lactoglobulin foamability was only marginally affected by the presence of F127, while it was reduced in an interval of low P85 concentrations. The protein foam stability was retained in the presence of the larger polymer F127, whereas P85 largely reduced the stability, indicating that the size of the polymeric surfactant is important. The results are discussed in relation to surface rheological properties and forces acting across foam films. Steric repulsion generated between the surfaces of foam films is suggested to be the main stabilizing factor in dry foam containing F127. The instability of the mixed ss-lactoglobulin/P85 system is suggested to be caused by two effects. First, there are incompatible stabilization mechanisms of block copolymer and protein, as supported by previous surface rheological data. Second, there is a reduced importance of long-range steric repulsion when P85 is added, compared to the case where F127 and ss-lactoglobulin are mixed.
Place, publisher, year, edition, pages
2006. Vol. 27, no 4, 527-536 p.
protein, beta-lactoglobulin, block copolymer, nonionic polymeric surfactant, foamability, foam stability, drainage, adsorbed protein layers, aba triblock copolymers, air-water-interface, nonionic surfactant, molecular-diffusion, air/water interface, liquid interfaces, aqueous-solution, films, stability
IdentifiersURN: urn:nbn:se:kth:diva-15597DOI: 10.1080/01932690500374300ISI: 000236740700014ScopusID: 2-s2.0-33645869579OAI: oai:DiVA.org:kth-15597DiVA: diva2:333639
QC 201005252010-08-052010-08-052010-10-11Bibliographically approved