Production and functional properties of micellar casein/κ-carrageenan aggregates

When mixtures of reconstituted skim milk powder (SMP; 10.5% solids) and κ-carrageenan (0.025%) were cooled from 60 to 25 °C while shearing, casein micelles and κ-carrageenan formed 10–100 μm aggregates. Aggregation decreased with increasing total milk solids at constant casein:κ-carrageenan ratios. Reducing ionic concentration from reconstituted SMP by ultrafiltration prior to κ-carrageenan addition restored aggregate formation, thus enabling production of a spray-dried powder containing 10–100 μm aggregates. When reconstituted, the aggregate powder had a lower viscosity than an unaggregated mixture of κ-carrageenan and skim milk and was very close to the retentate at the same concentration. Acidification and rennet gelation of the aggregates were greatly modified compared with the unaggregated mixture. A process for the manufacture of aggregated casein micelles in skim milk powder has been demonstrated.