Table 5.
Effect of drying method on the mean values of β-carotene (μg/100 g), ascorbic acid (mg/100 g), total phenols content (TPC, mg GAE/g), total antioxidant activity (TAA, % DPPH inhibition) (±SD) and percent daily value (%DV∗, as is basis) of stinging nettle and spinach∗∗∗ leaves.
| Drying method (DM) |
Fresh |
Freeze dried |
Oven dried |
p-values |
|||||
|---|---|---|---|---|---|---|---|---|---|
| Species (SP) | Nettle | Spinach | Nettle | Spinach | Nettle | Spinach | SP | DM | SP x DM |
| β-carotene | 58059a (243) | 44160d (256) | 56341b (453) | 43537d (62) | 52504c (447) | 40847e (479) | 0.01 | 0.01 | 0.01 |
| Vitamin A, μg RAE∗∗/serving | 728 | 383 | 659 | 508 | 634 | 488 | |||
| % DV | 83.7 | 44.0 | 75.7 | 58.4 | 72.9 | 56.0 | |||
| Ascorbic acid | 94.7a (3.3) | 77.0c (0.5) | 83.8b (2.3) | 75.7c (0.6) | 68.5d (0.6) | 65.3d (2.1) | 0.01 | 0.01 | 0.01 |
| Vitamin C, mg/serving | 14.2 | 8.0 | 11.8 | 10.6 | 9.9 | 9.4 | |||
| % DV | 23.7 | 13.3 | 19.6 | 17.7 | 16.5 | 15.6 | |||
| TPC | 118.4b (0.8) | 87.3d (3.9) | 121.5b (3.8) | 111.0c (1.5) | 128.7a (1.3) | 117.8b (0.2) | 0.01 | 0.01 | 0.01 |
| TAA | 65.1b (1.6) | 52.9c (1.6) | 66.6b (1.7) | 55.1c (0.5) | 70.6a (0.9) | 65.1b (0.6) | 0.01 | 0.01 | 0.01 |
a-d Means within same row with different superscripts are different (p < 0.05) when analysed using analysis of variance.
Without ‘db’ represent dry basis.
∗∗∗
Spinach leaves were used as anexternal reference sample.
∗∗
represent vitamin A content of fresh and dried leaves was calculated as retinol activity equivalents (RAE) using an RAE conversion factor of 12 μg β-carotene to 1 μg retinol (Joint FAO/WHO, 2001).
∗
represent percent contribution from a serving of 100 g fresh or 15 g dried stinging nettle or spinach leaves to the daily value of vitamin A and C was calculated as described by US FDA (2013) using the following equation: