Table 1.
Analysis of phenolic compounds (mg/L) in MF, NF and RO samples by UHPLC.
| Phenolic Compounds | Feed | MF-P | NF-R | NF-P | RO-R | RO-P |
|---|---|---|---|---|---|---|
| Caffeic acid | 8.1 ± 0.5 c | 7.6 ± 0.5 d | 27.7 ± 1.4 b | 1.8 ± 0.2 e | 45.7 ± 1.2 a | 0.5 ± 0.03 f |
| p-Coumaric acid | 6.4 ± 0.4 c | 4.3 ± 0.2 d | 12.2 ± 0.8 b | 2.6 ± 0.2 e | 35.9 ± 1.6 a | nd |
| Ferulic acid | 6.9 ± 0.6 c | 6.3 ± 0.3 d | 20.1 ± 1.1 b | nd | 51.3 ± 1.4 a | nd |
| Luteolin | 15.2 ± 0.6 c | 13.7 ± 1.1 d | 71.5 ± 2.7 b | nd | 82.8 ± 3.1 a | nd |
| 4-Hydroxyphenyl acetate | 72.6 ± 1.8 a | 67.0 ± 2.6 b | 29.6 ± 1.2 e | 64.0 ± 3.2 c | 57.1 ± 1.2 d | nd |
| Hydroxytyrosol | 373.3 ± 4.8 c | 320.1 ± 5.8 d | 1017.5 ± 8.8 b | 268.3 ± 1.2 e | 1522.2 ± 7.3 a | 18.8 ± 1.2 f |
| Oleuropein | 106.8 ± 4.0 c | 85.2 ± 2.7 d | 263.2 ± 4.2 b | nd | 510.0 ± 5.5 a | nd |
| Tyrosol | 89.7 ± 2.1 c | 68.1 ± 5.1 d | 157.3 ± 4.3 b | 64.8 ± 1.2 e | 519.0 ± 6.2 a | 5.0 ± 0.6 f |
| Vanillic acid | 29.4 ± 0.3 c | 27.8 ± 1.7 d | 97.0 ± 2.5 b | 6.5 ± 0.9 e | 116.2 ± 3.1 a | 1.4 ± 0.1 f |
| Verbascoside | 26.7 ± 1.1 c | 18.0 ± 1.3 d | 82.8 ± 3.4 b | nd | 130.9 ± 1.2 a | nd |
MF, microfiltration; NF, nanofiltration; RO, reverse osmosis; P, permeate; R, retentate. Data are expressed as mean ± S.D.; Differences were evaluated by one-way analysis of variance (ANOVA) completed with a multicomparison Tukey’s test. Means in the same row with different small letters differ significantly (p < 0.05). nd: not detected.