Table 3. Lactic Acid and SCFA Concentrations (mM) in Fermentation Broth with Different Ratios of SDF Substrates and at 16, 32, and 48 h of In Vitro Fermentationa.
| item | SDF 0% | SDF 25% | SDF 50% | SDF 75% | SDF 100% | P value |
|---|---|---|---|---|---|---|
| 16 h | ||||||
| lactic acid | 1.04 ± 0.03d | 1.68 ± 0.13c | 1.74 ± 0.10c | 2.25 ± 0.02b | 1.75 ± 0.07c | <0.01 |
| formic acid | 0.12 ± 0.01d | 1.32 ± 0.36c | 1.17 ± 0.07c | 2.46 ± 0.05b | 1.30 ± 0.08c | <0.01 |
| acetic acid | 0.47 ± 0.03d | 0.81 ± 0.11c | 0.77 ± 0.05c | 1.23 ± 0.02b | 0.79 ± 0.04c | <0.01 |
| propionic acid | 0.46 ± 0.03d | 4.14 ± 0.97c | 3.83 ± 0.27c | 7.19 ± 0.10b | 4.13 ± 0.36c | <0.01 |
| butyric acid | 0.06 ± 0.03 | 0.05 ± 0.01 | 0.06 ± 0.02 | 0.07 ± 0.00 | 0.08 ± 0.02 | 0.69 |
| 32 h | ||||||
| Lactic acid | 1.21 ± 0.04e | 1.54 ± 0.16de | 6.79 ± 0.80cd | 9.20 ± 0.25bc | 14.53 ± 2.72b | <0.01 |
| Formic acid | 1.14 ± 0.01d | 9.54 ± 0.20cd | 11.28 ± 2.48c | 25.78 ± 0.99b | 31.72 ± 3.83b | <0.01 |
| Acetic acid | 3.49 ± 0.20d | 10.11 ± 0.26c | 12.43 ± 0.54c | 21.60 ± 1.26b | 26.58 ± 2.67b | <0.01 |
| Propionic acid | 0.36 ± 0.10 | ND | ND | ND | ND | |
| Butyric acid | 0.13 ± 0.13 | ND | ND | ND | ND | |
| 48 h | ||||||
| Lactic acid | 0.13 ± 0.13d | 1.40 ± 0.12d | 6.30 ± 0.11c | 10.86 ± 1.19b | 12.69 ± 1.14b | <0.01 |
| Formic acid | 1.05 ± 0.09e | 10.45 ± 0.40d | 16.06 ± 1.30d | 28.16 ± 1.62c | 39.13 ± 2.86b | <0.01 |
| Acetic acid | 3.70 ± 0.09e | 11.11 ± 0.14d | 12.28 ± 0.82d | 24.16 ± 0.93c | 28.64 ± 1.07b | <0.01 |
| Propionic acid | 0.35 ± 0.11 | ND | ND | ND | ND | |
| Butyric acid | 0.13 ± 0.11 | ND | ND | ND | ND | |
a
Data are presented as mean ± SEM (n = 6), and values in the same row with different letter superscripts (b–e) means a significant difference (P < 0.05). ND means that the metabolites are undetectable and multiple comparisons cannot be made. SDF 0% means SDF/IDF = 0:1; SDF 25% means SDF/IDF = 1:3; SDF 50% means SDF/IDF = 1:1; SDF 75% means SDF/IDF = 3:1; and SDF 100% means SDF/IDF = 1:0.