Table 2.
Changes in pH, turbidity and color parameters of milk processed with HHP (600 MPa/15 min), pasteurization (72 °C/15 s) and pasteurization-HHP (72 °C/15 s + 600 MPa/15 min) during storage at 4 °C.
| Day | ||||||||
|---|---|---|---|---|---|---|---|---|
| 0 | 3 | 7 | 11 | 15 | 22 | 30 | ||
| pH | Untreated | 6.45 ± 0.15 Ac | - | - | - | - | - | - |
| 600 MPa/15 min | 6.45 ± 0.07 Ab | 6.36 ± 0.04 ab | 6.36 ± 0.04 ab | 6.26 ± 0.13 ab | 6.31 ± 0.11 ab | 6.25 ± 0.02 ab | 6.26 ± 0.07 ab | |
| 72 °C/15 s | 6.68 ± 0.01 Bd | 6.66 ± 0.01 d | 6.64 ± 0.01 cd | 6.66 ± 0.01 d | 6.59 ± 0.01 c | 6.43 ± 0.01 b | 6.18 ± 0.07 a | |
| 72 °C/15 s + 600MPa/15 min | 6.69 ± 0.01 Be | 6.64 ± 0.02 c | 6.65 ± 0.01 cd | 6.68 ± 0.02 de | 6.69 ± 0.01 e | 6.56 ± 0.01 b | 6.39 ± 0.01 a | |
| Turbidity (NTU) | Untreated | 384.10 ± 11.74 Bb | - | - | - | - | - | - |
| 600 MPa/15 min | 326.10 ± 18.67 Aab | 324.60 ± 15.70 ab | 305.40 ± 23.33 a | 309.23 ± 17.93 a | 356.00 ± 4.24 b | 328.75 ± 22.41 ab | 330.00 ± 2.12 ab | |
| 72 °C/15 s | 422.30 ± 43.70 Bab | 408.5 ± 52.18 ab | 388.70 ± 15.70 ab | 383.00 ± 5.09 ab | 448.70 ± 1.27 b | 400.80 ± 50.35 ab | 362.00 ± 2.55 a | |
| 72 °C/15 s + 600 MPa/15 min | 325.45 ± 45.75 Aab | 341.05 ± 4.17 ab | 297.00 ± 2.12 ab | 293.40 ± 7.21 ab | 335.95 ± 8.84 b | 327.9 ± 0.85 ab | 313.20 ± 0.42 a | |
| L* | Untreated | 82.76 ± 0.27 B | - | - | - | - | - | - |
| 600 MPa/15 min | 80.79 ± 0.39 Aab | 80.91 ± 0.65 b | 80.36 ± 0.68 ab | 80.53 ± 0.61 ab | 80.85 ± 0.93 ab | 79.90 ± 0.10 a | 80.24 ± 0.21 ab | |
| 72 °C/15 s | 82.64 ± 0.94 Bbc | 81.945 ± 0.57 ab | 82.80 ± 0.22 c | 83.22 ± 0.23 cd | 83.77 ± 0.16 d | 82.57 ± 0.34 bc | 81.43 ± 0.14 a | |
| 72 °C/15 s + 600 MPa/15 min | 81.26 ± 0.66 Abc | 80.98 ± 0.44 b | 81.64 ± 0.14 cd | 81.81 ± 0.24 cd | 82.17 ± 0.33 d | 80.84 ± 0.67 b | 80.04 ± 0.03 a | |
| a* | Untreated | −1.51 ± 0.06 B | - | - | - | - | - | - |
| 600 MPa/15 min | −1.71 ± 0.05 Abc | −1.62 ± 0.40 c | −1.88 ± 0.03 b | −2.13 ± 0.07 a | −1.69 ± 0.06 bc | −1.79 ± 0.04 bc | −1.19 ± 0.04 d | |
| 72 °C/15 s | −1.49 ± 0.06 Bb | −1.27 ± 0.05 c | −1.70 ± 0.14 a | −1.77 ± 0.06 a | −1.51 ± 0.05 b | −1.43 ± 0.06 b | −1.18 ± 0.036 c | |
| 72 °C/15 s + 600 MPa/15 min | −1.73 ± 0.05 Ab | −1.56 ± 0.07 c | −1.87 ± 0.11 a | −1.93 ± 0.04 a | −1.72 ± 0.043 b | −1.64 ± 0.03 bc | −1.31 ± 0.06 d | |
| b* | Untreated | 1.95 ± 0.17B | - | - | - | - | - | - |
| 600 MPa/15 min | 1.36 ± 0.31 Abc | 1.46 ± 0.32 bc | 1.48 ± 0.35 bc | 1.61 ± 0.25 c | 1.06 ± 0.36 ab | 0.71 ± 0.32 a | 3.08 ± 0.10 d | |
| 72 °C/15 s | 2.20 ± 0.16 Bbc | 2.32 ± 0.44 c | 1.27 ± 0.14 a | 1.86 ± 0.35 b | 2.18 ± 0.08 bc | 2.14 ± 0.14 bc | 3.11 ± 0.06 d | |
| 72 °C/15 s + 600 MPa/15 min | 1.46 ± 0.21 Aa | 1.65 ± 0.20 a | 1.68 ± 0.13 a | 1.59 ± 0.18 a | 1.45 ± 0.06 a | 1.49 ± 0.26 a | 3.16 ± 0.05 b | |
| ΔE | Untreated | 0 | - | - | - | - | - | - |
| 600 MPa/15 min | 4.24 | 3.66 | 6.1 | 5.47 | 4.45 | 9.79 | 7.72 | |
| 72 °C/15 s | 0.08 | 0.86 | 0.50 | 0.29 | 1.07 | 0.76 | 3.22 | |
| 72 °C/15 s + 600 MPa/15 min | 2.52 | 3.25 | 1.44 | 1.20 | 0.65 | 3.91 | 8.88 | |
-, not tested. Values in the same column with different superscript capital letters indicate significant differences between the samples after different treatments (p < 0.05). Values in the same line with different superscript lowercase letters indicate significant changes of one sample during storage (p < 0.05).