Table 2.
Colour attributes of beetroot powder under varying drying condition and slice thickness.
| Drying parameter | Slice thickness (mm) | Total colour difference (∆E) | Browning index (BI) | |
|---|---|---|---|---|
| Power level (W) | Vacuum (mm Hg) | |||
| Microwave vacuum drying | ||||
| 160 | 710 | 1 | 6.99 ± 0.44ᵇ | 93.01 ± 2.10ᵇ |
| 320 | 710 | 1 | 5.90 ± 0.36ᶜ | 82.11 ± 5.78ᶜ |
| 160 | 660 | 1 | 7.63 ± 0.22ᵇ | 100.47 ± 3.77ᵇ |
| 320 | 660 | 1 | 5.62 ± 1.01ᶜ | 86.27 ± 4.77ᶜ |
| 160 | 610 | 1 | 11.22 ± 1.76ᵃ | 147.49 ± 18.59ᵃ |
| 320 | 610 | 1 | 6.87 ± 0.76ᵇ | 103.99 ± 1.44ᵇ |
| 160 | 710 | 2 | 6.60 ± 0.59ᵇ | 80.49 ± 3.79ᶜ |
| 320 | 710 | 2 | 10.60 ± 0.38ᵃ | 65.62 ± 1.19ᵈ |
| 160 | 660 | 2 | 4.70 ± 0.30ᶜ | 104.32 ± 3.07ᵇ |
| 320 | 660 | 2 | 7.11 ± 0.75ᵇ | 79.93 ± 13.10ᶜ |
| 160 | 610 | 2 | 4.86 ± 0.35ᶜ | 126.08 ± 3.72ᵃ |
| 320 | 610 | 2 | 4.50 ± 1.32ᶜ | 99.20 ± 2.96ᵇ |
| Freeze drying (0.062 m bar, −40 °C) | 1 | 4.84 ± 0.99ᶜ | 102.88 ± 8.32ᵇ | |
| 2 | 2.42 ± 1.21ᶜ | 80.95 ± 13.74ᶜ | ||
Different superscript small letters in each column denote significant difference at p ≤ 0.05.