Influence of protein concentration and homogenisation pressure on O/W emulsifying and emulsion-stabilising properties of sodium caseinate and whey protein isolate.

Since both whey protein isolate and sodium caseinate are frequently used O/W emulsifiers of dairy origin, their emulsifying and emulsion stabilising properties have been determined at pH conditions that ressemble practical circumstances. In order to enable a quantitative evaluation, two 3-level experimental designs were set-up considering the effect of homogenisation pressure and protein concentration on average droplet size, residual serum protein concentration as well as serum separation of 20% O/W emulsions. Although both proteins were characterised by a similar surface load, still the residual protein content indicated that sodium caseinate was much more surface active. The results revealed that either 0.25% sodium caseinate or 0.50% of whey protein isolate at a homogenisation pressure of 200 bar not only yielded stable emulsions, but also limited the amount of unadsorbed protein in the continuous phase.