Abstract
Using the DDS plate-and-flame module fitted with three kinds of RO membrane made from different materials (cellulose acetate, composite membrane, polyacrylonitrile (PAN)), operating conditions and comparison of each membrane's suitability to concentrate fruit juice were studied. The osmotic pressure of fruit juices and sugar solutions was measured by using RO equipment. The osmotic pressures of glucose and fructose were the same and 1.9 times greater than that of sucrose solution. The osmotic pressures of fruit juices of 10°, 20°, and 30° Bx were 11-15, 26-34, and 46-60 kg/cmcm2, respectively. Sugar composition of fruit juice had great influence on the osmotic pressure. Using clarified juice, the variation of permeation rate with various pressures, temperatures, and flow rates was examined. The permeation rate dependency on flow rate and temperature was similar for each membrane, but the dependency on pressure differed slightly. The operating factor found to be most effective in increasing permeation rate was operating pressure, which was followed by temperature and flow rate.
