Potassium acetate solution as a promising option to osmotic distillation for sour cherry (Prunus cerasus L.) juice concentration

Different osmotic agents (OA), such as potassium acetate (CH3COOK), potassium carbonate (K2CO3) and ammonium nitrate (NH4NO3), have been examined as alternatives to the traditionally used calcium chloride (CaCl2) for osmotic distillation concentrating of clarifi ed and pre-concentrated sour cherry (Prunus cerasus L.) juice. Comparison of the process performances based on the permeate fl uxes has been carried out. Regarding the permeate fl ux results, simplifi ed estimation of the overall mass transfer coeffi cient of the most effective osmotic agent and the reference (CaCl2) solution has been also performed. Furthermore, analytical methods such as total antioxidant activity (TAA) and total polyphenolic content (TPC) using spectrophotometric assays have been also carried out to evaluate the effect of the osmotic distillation on the valuable compounds content of concentrated sour cherry juice. CH3COOK was found to be the most effective, resulted more than 25% higher permeate fl ux during the sour cherry juice concentration. K2CO3 and NH4NO3 were less effective. The simplifi ed mass transfer estimation showed that the CH3COOK is more effective only at near saturated concentrations compared to the CaCl2. Regarding the TAA and TPC contents, a signifi cant loss was found in case of all OAs during the concentration procedures.