Effect of κ-carrageenan addition to dairy emulsions containing sodium caseinate and locust bean gum

Sodium caseinate-stabilized emulsions containing locust bean gum (LBG) were formulated to resemble soft-serve ice cream mixes, in order to study the effect of κ-carrageenan on the inhibition of phase separation in such systems. These emulsions behaved very different than skim milk powder (SMP)-stabilized emulsions, at similar protein concentration. Fat globule creaming was observed, due to depletion flocculation between sodium caseinate-coated fat droplets and excess sodium caseinate in solution. The cream layers were not enriched in protein, in contrast to SMP emulsions, in which the creamy layer after phase separation contained almost 90% of the casein. However, sodium caseinate and LBG were shown to be incompatible by confocal scanning laser microscopy, leading to a microscopic phase separation. κ-carrageenan was not as effective at inhibiting the formation of the cream layer in sodium caseinate emulsions compared to inhibition of phase separation in SMP systems, and its functionality was attributable to κ-carrageenan self-association, rather than to interaction with casein proteins, again in contrast to SMP systems. The addition of calcium ions improved κ-carrageenan functionality.