Table 4.
Changes in hydroxytyrosol content during the spontaneous fermentation of Spanish-style green olive processing wastewaters under different temperature and initial pH conditions.
| Fermentation Conditions | Hydroxytyrosol Content (mg/L) 1 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Temperature | Initial pH Value | Fermentation Time (d) | ||||||||
| 1 | 2 | 10 | 20 | 30 | 60 | 120 | 180 | 360 | ||
| 15 °C | 3.5 | 420.9 ± 26.7 a,A | 371.6 ± 16.8 b,A | 349.3 ± 15.4 bc,A | 328.0 ± 15.9 c,AF | 326.8 ± 15.4 c,A | 474.7 ± 24.5 d,A | 490.5 ± 16.8 d,A | 195.9 ± 11.3 e,A | 72.6 ± 5.1 f,A |
| 5.0 | 417.3 ± 17.5 a,AD | 356.6 ± 13.6 b,AF | 359.3 ± 12.5 b,A | 418.2 ± 18.8 a,B | 328.0 ± 16.1 c,A | 332.5 ± 11.5 bc,B | 501.2 ± 19.2 d,AH | 273.0 ± 12.6 e,B | 120.4 ± 9.2 f,B | |
| 11.5 | 234.0 ± 10.0 a,B | 135.6 ± 5.4 bc,B | 133.6 ± 9.5 b,B | 150.4 ± 8.2 bc,C | 152.9 ± 8.2 c,B | 238.0 ± 17.0 a,C | 222.5 ± 14.1 a,B | 35.6 ± 4.5 d,C | 2.2 ± 0.1 e,C | |
| 30 °C | 3.5 | 336.7 ± 13.5 a,C | 324.6 ± 13.0 a,C | 363.7 ± 19.7 b,A | 319.5 ± 13.5 a,A | 291.9 ± 9.9 c,C | 361.9 ± 15.4 b,D | 443.7 ± 17.4 d,C | 258.6 ± 12.7 e,B | 59.7 ± 2.1 f,D |
| 5.0 | 392.8 ± 15.1 ad,D | 332.5 ± 13.9 b,C | 431.5 ± 15.1 c,C | 433.1 ± 16.9 c,B | 377.1 ± 14.7 a,D | 409.6 ± 16.9 cd,E | 552.9 ± 26.9 e,D | 240.1 ± 19.3 f,D | 112.8 ± 7.7 g,E | |
| 11.5 | 231.0 ± 14.1 a,B | 210.1 ± 10.2 b,D | 207.2 ± 8.6 b,D | 254.0 ± 13.3 c,D | 259.9 ± 15.6 c,E | 266.8 ± 13.3 c,F | 206.8 ± 12.9 b,B | 45.5 ± 5.9 d,C | 13.2 ± 1.2 e,F | |
| 50 °C | 3.5 | 343.0 ± 16.1 a,C | 295.0 ± 15.4 b,E | 324.9 ± 12.9 a,E | 295.2 ± 13.8 b,E | 295.3 ± 12.2 b,C | 302.0 ± 14.0 b,G | 343.1 ± 16.1 a,E | 144.5 ± 7.0 c,E | 54.3 ± 1.7 d,D |
| 5.0 | 339.8 ± 16.7 a,C | 335.6 ± 14.5 a,CF | 308.0 ± 13.9 b,E | 346.2 ± 13.1 a,FH | 220.7 ± 10.8 c,F | 231.5 ± 11.1 c,C | 253.8 ± 8.6 d,F | 84.0 ± 5.8 e,F | 23.7 ± 0.9 f,G | |
| 11.5 | 194.1 ± 7.2 ab,E | 207.9 ± 7.6 a,D | 208.5 ± 9.6 a,D | 203.3 ± 9.5 ab,G | 189.4 ± 9.4 b,G | 133.0 ± 12.0 c,H | 139.6 ± 8.9 c,G | 7.5 ± 0.7 d,G | 0.0 ± 0.0 d,C | |
| Room temperature |
3.5 | 323.4 ± 14.3 a,C | 267.9 ± 11.7 b,G | 418.5 ± 20.7 c,C | 432.7 ± 18.0 ce,B | 365.0 ± 16.6 d,D | 446.4 ± 15.0 e,I | 519.3 ± 16.8 f,H | 298.3 ± 14.2 a,H | 144.9 ± 6.9 g,H |
| 5.0 | 324.9 ± 17.4 a,C | 321.8 ± 14.8 a,C | 355.7 ± 17.6 b,A | 365.4 ± 15.2 b,H | 320.9 ± 11.7 a,A | 382.2 ± 14.3 b,D | 456.3 ± 19.4 c,C | 233.9 ± 13.9 d,D | 107.2 ± 4.2 e,E | |
| 11.5 | 203.5 ± 7.5 a,E | 241.0 ± 15.3 b,H | 175.2 ± 10.2 c,F | 159.4 ± 12.4 d,C | 63.1 ± 4.6 e,H | 0.0 ± 0.0 f,J | 0.0 ± 0.0 f,I | 0.0 ± 0.0 f,G | 0.0 ± 0.0 f,C | |
1 Initial hydroxytyrosol content: 280.5 mg/L ± 10.9 mg/L. Data are the mean ± standard deviation (n = 3). Different lowercase letters in the same row or capital letters in the same column represent significant differences in values (p < 0.05).