Table 1.
Comparisons between the extraction yield, TPC, OD420 value, and contents of FF and HMF in the extracts obtained from PHWE at different temperatures and from conventional extractions.
| Extracts | Extraction Yield (%) | TPC (mg GAE/g RM) |
Browning Intensity (OD420) |
FF µg/g RM |
HMF µg/g RM |
|---|---|---|---|---|---|
| Maceration | 3.31 ± 0.06 a | 1.29 ± 0.22 a | 0.28 ± 0.00 a | ND | ND |
| Reflux | 7.1 ± 0.4 b | 2.56 ± 0.15 c | 0.50 ± 0.02 b | ND | ND |
| PHWE 100 °C | 7.60 ± 0.21 c | 1.58 ± 0.05 b | 0.30 ± 0.02 a | ND | ND |
| PHWE 120 °C | 8.75 ± 0.17 d | 2.0 ± 0.5 bc | 0.30 ± 0.01 a | ND | ND |
| PHWE 140 °C | 9.2 ± 0.7 d | 3.28 ± 0.06 d | 0.39 ± 0.02 a | ND | 69 ± 6 a |
| PHWE 160 °C | 14.18 ± 0.09 e | 5.11 ± 0.10 e | 0.54 ± 0.01 b | 221 ± 16 a | 523 ± 25 b |
| PHWE 180 °C | 22.6 ± 0.7 f | 7.6 ± 0.4 f | 0.72 ± 0.11 c | 2805 ± 97 b | 2246 ± 36 c |
Results are expressed as mean ± standard deviations (SD) (n = 3). Values represented with different lowercase letters are statistically significant differences (p < 0.05). TPC: total phenolic content, OD420: optical density measured at 420 nm, FF: furfural, HMF: 5-hydroxymethylfurfural, PHWE: pressurized hot water extraction, ND: Not detected, RM: raw material of Bambusa chungii culms.