Opportunities and Challenges in Application of Forward Osmosis in Food Processing.

Food processing and preservation technologies must maintain the fresh-like characteristics of food while providing an acceptable and convenient shelf life as well as assuring safety and nutritional value. Besides, the consumers' demand for the highest quality convenience foods in terms of natural flavor and taste, free from additives and preservatives necessitated the development of a number of membrane-based non-thermal approaches to the concentration of liquid foods, of which forward osmosis has proven to be the most valuable one. A series of recent publications in scientific journals have demonstrated novel and diverse uses of this technology for food processing, desalination, pharmaceuticals as well as for power generation. Its novel features, which include the concentration of liquid foods at ambient temperature and pressure without significant fouling of membrane, made the technology commercially attractive. This review aims to identify the opportunities and challenges associated with this technology. At the same time, it presents a comprehensive account of recent advances in forward osmosis technology as related to the major issues of concern in its rapidly growing applications in food processing such as concentration of fruit and vegetable juices (grape, pineapple, red raspberry, orange, and tomato juice and red radish juice) and natural food colorants (anthocyanin and betalains extracts). Several vibrant and vital issues such as recent developments in the forward osmosis membrane and concentration polarization aspects have been also addressed. The asymmetric membrane used for forward osmosis poses newer challenges to account both external and internal concentration polarization leading to significant reduction in flux. The recent advances and developments in forward osmosis membrane processes, mechanism of water transport, characteristics of draw solution and membranes as well as applications of forward osmosis in food processing have been discussed.