# Concentrations of Beetroot (_Beta vulgaris_ L.) Peel and Flesh Extracts by Reverse Osmosis Membrane
## 3 Results  
### 3.1. Betalains, TPC, and Antioxidant Compounds Recovery by RO Membrane (X20)  
Spectrophotometric analysis was conducted for the quantification of TBC, TPC, and antioxidant compounds in aqueous extract, membrane permeate, and retentate. Retention percentages of mentioned biomolecules were calculated from the concentration data. As betalains, TPC, and antioxidant compounds were not determined in the permeates, it can be concluded that mentioned biomolecules were rejected by the RO membrane at more than 99%.  
The determined amounts of BC, BX, and TBC in each sample are shown in Table 1. The BC contents in membrane feeds for betroot peel and flesh were 4.06 \(\pm\) 0.11 mg\(\cdot\)g\({}^{-1}\) dm and 1.72 \(\pm\) 0.03 mg\(\cdot\)g\({}^{-1}\) dm, respectively. These values in retentate went up constantly with progresses of VRR. They reached 15 \(\pm\) 0.17 mg\(\cdot\)g\({}^{-1}\) dm and 8.98 \(\pm\) 0.11 mg\(\cdot\)g\({}^{-1}\) dm in final retentates of betroot peel and flesh extracts, respectively. The amount of BX in betroot peel extract was 3.02 \(\pm\) 0.15 mg\(\cdot\)g\({}^{-1}\) dm, and it became 15.06 \(\pm\) 0.13 mg\(\cdot\)g\({}^{-1}\) dm at the end of filtration. In the flesh extract, the amount of BX was 0.89 \(\pm\) 0.03 mg\(\cdot\)g\({}^{-1}\) dm, and it went up to 5.39 \(\pm\) 0.04 mg\(\cdot\)g\({}^{-1}\) dm at the end of the filtration process. The amount of TBC in extract of betroot peel was 7.22 \(\pm\) 0.06 mg\(\cdot\)g\({}^{-1}\) dm, which was three times greater than the flesh extract (2.6 \(\pm\) 0.05 mg\(\cdot\)g\({}^{-1}\) dm). Likewise, the TBC in peel extract was increased more than four times after membrane filtration, whereas it was increased more than five times for flesh extract. Betalain contents in each sample were varied during membrane filtrations. In Figure 1, betalain content is presented with the function of VRR. Concentration ratio (CR) of TBC in final retentates of betroot peel was 4.16. These values were 3.69 and 4.99 for BC and BX, respectively. The betroot flesh filtrates exhibited CR of 5.22 for BC, 6.04 for BX, and 5.52 for TBC.  
Figure 1: Variation of betalains during the concentration by RO membrane (X20).  
Flux behaviors for filtration of beetroot peel and flesh extracts by RO membrane with different VRRs are shown in Figure 4. In both cases, permeate flux was reduced with the increase of VRR. Reduction of permeate flux was more for flesh extract compared to peel extract. VRR reached 1.5, 2, 2.5, and 3 at 7.4, 11.6, 14.3, and 15.8 min of filtration time, respectively, in the case of flesh extract. On the other hand, VRR reached 1.5, 2, 2.5, and 3 at 6.5, 9.7, 11.9, and 13.4 min of filtration time, respectively, in the case of peel extract.  
From pure water flux measurements, after the concentration process of beetroot peel and flesh extracts, fouling resistances of membranes were calculated. Those are depicted in Figure 5. No significant difference in fouling resistance is observed between peel and flesh concentrations.  
Figure 4: Permeate flux with VRR during the concentration process by RO membrane (X20).  
Figure 3: Variation of antioxidant capacity with VRR during concentration by RO membrane (X20).