Fructooligosaccharides (FOS) were fractionated using nanofiltration cascades. Instead of creating one product and a residual stream, we report on configurations that create 3 separate product streams rich in: (1) monosaccharides (DP1), (2) DP3 and (3) DP ≥ 5. We developed a modular system allowing different operating pressures and membrane types at each stage. Two possible alternative configurations were assessed for a 3-stage cascade both experimentally and via simulation. The simulation was performed using a steady state model and was in a good agreement with the experimental data. Using the simulation model, the system was optimized towards 4 and 5 stage cascades. All designs were evaluated based on the purities and yields of 3 components of interest in the corresponding product streams. Selecting the correct set up, the cascade was able to reach maximum purity of monosaccharides to 66 wt% (from 9 wt%), DP3 to 33 wt% (from 24 wt%) and DP ≥ 5 to 54 wt% (from 34 wt%). Increasing the number of stages improved the maximum purities of the 3 fractions. However, a fifth stage did not increase the purification and the best purities were found using 4-stage rather than 5-stage cascades.
- Membrane cascades