Advancement of forward osmosis (FO) membrane for fruit juice concentration

Simultaneous fruit juice concentration and preservation of the heat-sensitive sensorial and nutritional components is a challenging topic in food processing. Forward-osmosis (FO) membrane is one of the promising alternatives to concentrate juice at low temperature and pressure. There are a number of negative propensities in FO operation, inter alia, internal and external concentration polarization, organic fouling, and product contamination due to back salt diffusion from the draw solution. To address these issues, preparation methods have been developed to obtain highly hydrophilic membrane with low fouling tendency, concentration polarization, and solute diffusion. The desired membrane has been obtained by modifying active and support layers of the membrane. Draw solutions are also optimized recently with desirable characteristics such as low reverse salt permeation, easy to re-concentrate, favorable price, stable and minimal toxicity. This paper reviews mechanism and principle of FO membrane technology, recent advancement of the membrane (including membrane preparation and modification, and important parameters), as well as challenges and strategies for the future development of FO membranes in fruit juice concentration.