Evaluation of Process Conditions and Food Quality in Carob Molasses Production by Osmotic Distillation

Abstract Carob fruit, rich in nutrients and beneficial for treating chronic gastrointestinal diseases, is typically consumed as a concentrated extract. However, conventional methods to process it in a concentrated form can alter its food quality due to the employment of high temperatures. In this work, carob molasses is produced by osmotic membrane distillation utilizing a hydrophobic hollow fiber membrane contactor. Carob extract of 12°Brix obtained by ultrasonication at 25 °C was employed as the feed solution while 4 M of CaCl 2 solution was used as the draw solution. The impacts of process temperature and the feed and draw solution flowrates on transmembrane flux in osmotic distillation were investigated. The highest water flux value was 378.7 g m −2 h −1 . The study compared osmotic distillation with thermal and vacuum evaporation methods in terms of physicochemical properties, color, antioxidant and phenolic activity, and 5-hydroxymethylfurfural (HMF) kinetics of the products obtained by each of said methods. The carob juice was concentrated to approximately 63°Brix from 12°Brix by each method. The products obtained by osmotic distillation contained higher phenolic (498.64 mg GAE/100 g) and antioxidant activity (434.05 mg TE/100 g) than the ones obtained by other methods. Furthermore, osmotic distillation avoided HMF formation. This research is a pioneer study on carob concentration using osmotic distillation. The study revealed key insights into extraction and optimization techniques and into the adaptability of osmotic distillation systems for obtaining food extracts. The experimental results show that with further research and technological advances, these systems could significantly impact the food industry.