Concentration of Sour Cherry Juice Using Osmotic Distillation G. Racz 1 , N. Papp 3 , A. Hegedűs 2 , E. Bányai 3 , G. Vatai 1 1 Corvinus University of Budapest, Department of Food Engineering 2 Corvinus University of Budapest, Department of Genetics and Plant Breeding 3 Corvinus University of Budapest, Department of Applied Chemistry Hungary 3 gabor.racz2@uni-corvinus.hu Sour cherry is one of the most famous and characteristic Hungarian fruit what is commonly used for in food production as colour additive. Valuable compounds in fruit juice –vitamins, polyphyenols, etc.- are heat and mechanical sensitive molecules and during the concentrate process should have to avoid from degradation. Osmotic distillation seems suitable option to product high quality of sour cherry juice because this process not requires high temperature or pressure. Raw juice with approximately 15°Brix was used for the experiment and tried to concentrate up to 60°Brix where the water activity enough low to inhibit the microbiological effects. Before and after the process TPC (total phenolic compounds) and AC (antioxidant capacity) was measured by spectrophotometric method to determine the effect of the osmotic distillation. Results point out that osmotic distillation is a promising method to make concentrated sour cherry juice while the valuable compounds could avoid the degradation. 1. Introduction Osmotic distillation is a kind of mass transfer driven membrane process where the driving force is the vapour pressure difference between two solutions. Similar that membrane distillation (MD) in case of OD is also used hyrdophobic, porous, polymeric membranes. For the osmotic distillation process usually high concentration of osmotic agent, mostly salt solution (NaCl, CaCl 2 , K 2 HPO 4, K–acetate) or some kind of organic solutions (polyethylene-glycol, glycerol, etc.) is used wich can keep and sustain very low value of vapour pressure during the process. These osmotic agents able to performe the suitable vapour pressure difference with the high concentration and low vapour pressure value between the two sloutions (Bailey et al. 2000; Cassano et al. 2007/a; Gostoli et al.1999; Hongvaleerat et al. 2008). OD process based on a phenomenon: between two aqueous solutions wich have different water actity occurs a volatile compound stream to equalize the vapour pressure different of the two solution. In case of OD a microporous hydrophobic membrane in present between these solutions wich is separate totally them from each other because of the hydrophobicity and surface energy. Thus aqueous solutions cannot penetrate into the pores than two liquid-vapour interface form at the entrances of the pores with different water activity. As a result, volatile compound molecules (water) evaporate from the higher water activity liquid-vapour interface (liquid food side), cross the pores by diffusion and condense at the lower water activity vapour-liquid interface (osmotic agent side). Figure 1. shows the flow sheet of the osmotic distillation process (Bélafi-Bakó et al. 2007; Courel et al. 2000/b; Mansuori et al. 1999; Thanedgunbaworn et al. 2007/a.)