Latest Development in Low Pressure Osmotic-based Membrane Separation for Liquid Food Concentration: A Review

Low-pressure osmotic-based membrane separation, such as osmotic membrane distillation (OMD) and forward osmosis (FO), is a separation process suitable for the concentration of liquid food with heat-sensitive components. In FO, a dense hydrophilic membrane is used with osmotic-pressure gradient as the driving force. Reverse salt diffusion and low osmotic gradient are major phenomena impeding the FO application. Food preservatives can be applied as the draw solutions, however, it is imperative to ensure the limit of food additives for safe consumption of the concentrated product. In OMD, a porous hydrophobic membrane is employed, and vapor-pressure difference acts as the driving force. Wetting is the major drawback for OMD industrialization that needs to be resolved. The application of dense membrane in OMD for liquid food concentration to overcome the wetting is highlighted in this study.