Enhancing the applicability of forward osmosis membrane process utilizing food additives as draw solutes

Abstract

Food additives as draw solutes were investigated to improve the feasibility of forward osmosis (FO) for concentration of liquid food products. Three widely used food additives were selected: monosodium glutamate (MSG), sodium saccharine, and trisodium citrate. The osmotic pressures generated by food additives were measured to be similar or even higher than that of NaCl. However, the water flux produced by FO using food additives was 70–78% lower than that of NaCl. This observation was mainly attributed to severe internal concentration polarization (ICP). Conversely, the reverse solute flux (RSF) of food additives in the FO process was low at only 3–9% of that of NaCl, suggesting they pose a low contamination. The FO process using MSG draw solutions yielded a 15% solid content of whey. To further improve FO concentration, pressure-assisted osmosis (PAO) was adopted for dewatering whey and lactose solutions. The PAO process applying a pressure of 10 bar to feed solution increased the water flux by 36% (whey) and 49% (lactose) with a 2 M MSG draw solution, thus demonstrating the potential of the developed FO/PAO with food additive draws for the food industry.