Sustainable dewatering of grapefruit juice through forward osmosis: Improving membrane performance, fouling control, and product quality

Abstract

Highly enriched grapefruit juice is expected to be obtained through forward osmosis (FO) without degradation of its nutrients. However, this technology is facing several key issues that must be explored to validate the suitability of FO as a dewatering process, namely, membrane performance testing, fouling control, and product quality assessment. In this work, grapefruit juice was dewatered using a commercial thin-film composite FO membrane that exhibited stable performance. The simulation results also suggested that the dewatering could be further enhanced by improving the S value of the current TFC FO membrane. Severe membrane fouling was observed, and it was predominantly due to suspended particles larger than 0.45 mu m, such as pectin. However, sustainable osmotic dewatering operation could be attained by implementing appropriate fouling control strategies, such as separating large-sized particles by sedimentation or centrifugation prior to osmosis and recovering the declined water flux by physical cleaning. The dehydrated feed exhibited no significant loss of nutritional value, suggesting that the FO membrane dewatered the juice effectively while retaining its constituents. In addition, the FO process could be further improved to obtain enhanced-quality grapefruit juice by applying pressure to the feed stream or employing a sugar-based draw solution such as glucose.