Forward osmosis and direct contact membrane distillation: Emerging membrane technologies in food and beverage processing

Thermal processes widely implemented in food and beverage manufacturing inevitably cause the deterioration of food quality such as nutritional and organoleptic properties. Moreover, the scarcity of freshwater resources around the globe necessitates the advance of technologies to manage the waste stream produced during food and beverage manufacturing operations. Many membrane filtration processes have been proposed to deal with such issues. Forward osmosis (FO) and direct contact membrane distillation (DCMD) have emerged as promising membrane technologies to be used for liquid food products/beverage concentration, water purification, or contaminant removal from processed products. The main advantages of FO and DCMD over conventional thermal processes and pressure-based filtration technologies include the use of low-grade waste heat, lack of hydraulic pressure, low fouling formation, and high concentration capability. In this review, the fundamentals governing the filtration mechanisms of FO or DCMD are first described. The advantages and limitations as well as detailed summaries of FO or DCMD application to the food industry are also presented. Next, the effects of operational parameters on the filtration performance FO or DCMD are discussed. Finally, the potential and application of a hybrid system, the integrated FO-DCMD, are examined to highlight this unique approach to food and beverage manufacturing.