CARRAGEENAN-THICKENED MILK BASE BY ULTRAFILTRATION

Solutions of 0.1% carrageenan were concentrated by ultrafiltration 4-5 fold in water and in milk using a ceramic membrane with a rated pore size of 500 Angstrom (1P19-40 US filter, Warrendale, PA). At a transme mbrane pressure of 103 kPa, cross flow velocity of 4 m/sec and tempera ture of 70 degrees C, flux for carrageenan-water system dropped from 3 00 l per square meter per h (LMH) at volume concentration ratio (VCR) 1 to 95.3 LMH at VCR 5. Flux was pressure dependent up to a pressure o f 200 kPa. For carrageenan-milk suspensions, flux dropped from an init ial value of 96.2 LMH to 21.3 LMH at a VCR of 4. In contrast, with mil k alone, flux dropped from 148.4 LMH to 23.3 LMH at VCR 4. Fluxes for the 2 milk systems were pressure independent above 50 kPa and flux inc reased at higher velocities, indicating that concentration polarizatio n was rate controlling. It was concluded that a liquid carrageenan (us e concentration 0.5%) and a thickened milk (0.4% carrageenan) can be p roduced by concentrating dilute solutions (0.1%) of carrageenan in wat er and in milk using ultrafiltration membranes.