Concentration of proteins as a result of the phase separation of the water‐protein‐polysaccharide systems Part 3. Regeneration and repeated use of the polysaccharide during concentration

Abstract

Earlier, with particular reference to skimmed milk, it has been shown that protein solutions can be concentrated by the membraneless osmosis. The practical significance of this method is determined by the possibility of the regeneration of the polysaccharide from its diluted so1ut;ons (from the polysaccharide phase) and its repeated use for protein concentration. This work deals with the possibility of pectin isolation from the polysaccharide phase resulting from the phase separation of the water-skimmed milk proteins-pectin system and its further use for milk protein concentration. The pectin was precipitated as a part of the insoluble complexes with milk proteins at pH values below their IEP. The complexes were destroyed at pH values being increased to 6.5-6.7 and the pectin obtained was used again in the process of the membraneless osmosis. In case of a single-cycle regeneration and repeated use of pectin the total loss of protein did not exceed 2.6:;and that of pectin 30 %. The amount of water removed with unit weight of pectin during a single-cycle pectin regeneration was 1.7 times higher than th&t which took place during concentratio? without subsequent regeneration. The additional energy expenditures due to the single-cycle regeneration and the repeated use of pectin did not exceed 15 % of the energy spent in all the cycles of protein concentration.