Table 4.
Effect of drying method on the mean minerals content (mg/100 g, db ± 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 |
| Ca | 2136a (182) | 500b (4) | 2283a (198) | 536b (4) | 2065a (133) | 543b (26) | 0.01 | 0.31 | 0.32 |
| Ca, mg/serving | 323 | 52 | 320 | 75 | 299 | 78 | |||
| % DV | 32.3 | 5.2 | 32 | 7.5 | 29.9 | 7.8 | |||
| Fe | 16.7a (0.7) | 7.5b (1.8) | 17.9a (0.7) | 8.0b (1.9) | 17.6a (1.8) | 8.3b (1.6) | 0.01 | 0.57 | 0.93 |
| Fe, mg/serving | 2.5 | 0.8 | 2.5 | 1.1 | 2.6 | 1.2 | |||
| % DV | 14 | 4.3 | 14 | 6.3 | 14.2 | 6.6 | |||
| Mg | 692a (13) | 430b (95) | 740a (14) | 460b (102) | 726a (32) | 411b (93) | 0.01 | 0.60 | 0.80 |
| Mg, mg/serving | 104 | 45 | 104 | 64 | 105 | 59 | |||
| % DV | 26 | 11.2 | 26 | 16.1 | 26.3 | 14.7 | |||
| Mn | 2.5ab (0.1) | 2.3c (0.1) | 2.7a (0.1) | 2.5bc (0.1) | 2.6ab (0.0) | 2.3bc (0.2) | 0.01 | 0.09 | 0.97 |
| Mn, mg/serving | 0.4 | 0.2 | 0.4 | 0.3 | 0.4 | 0.3 | |||
| % DV | 19.0 | 11.9 | 18.9 | 17.2 | 18.5 | 16.8 | |||
| Zn | 3.5a (0.1) | 2.4b (0.6) | 3.8a (0.1) | 2.6b (0.7) | 3.8a (0.2) | 2.5b (0.7) | 0.01 | 0.71 | 0.94 |
| Zn, mg/serving | 0.5 | 0.2 | 0.5 | 0.4 | 0.6 | 0.4 | |||
| % DV | 3.5 | 1.7 | 3.5 | 2.4 | 3.7 | 2.4 | |||
| P | 550a (31) | 543a (62) | 588a (33) | 582a (66) | 584a (47) | 558a (53) | 0.60 | 0.44 | 0.93 |
| P, mg/serving | 82.6 | 56.7 | 82.5 | 81.5 | 84.6 | 80 | |||
| % DV | 8.3 | 5.7 | 8.2 | 8.2 | 8.5 | 8.0 | |||
| K | 1266a (60) | 610b (73) | 1354a (62) | 653b (78) | 1278a (43) | 663b (91) | 0.01 | 0.30 | 0.58 |
| K, g/serving | 0.2 | 0.1 | 0.2 | 0.1 | 0.2 | 0.1 | |||
| % DV | 5.4 | 1.8 | 5.4 | 2.6 | 5.3 | 2.7 | |||
| Na | 3.1b (0.8) | 110.9a (25) | 3.3b (0.9) | 118.7a (26) | 3.4b (0.9) | 107.9a (26) | 0.01 | 0.87 | 0.87 |
| Na, g/serving | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |||
| % DV | 0.0 | 0.5 | 0.0 | 0.7 | 0.0 | 0.6 | |||
ab Means within same rowwith different superscripts are different (p < 0.05) when analysed using analysis of variance.
∗∗
Spinach leaves were used as anexternal reference sample.
∗
Percent contribution from a serving of 100 g fresh or 15 g dried stinging nettle or spinach leaves to the daily value of the specific mineral elements (e.g. 1000mg Ca, 18 mg Fe, 400 mg Mg, 2 mg Mn, 1000 g P, 15 mg Zn, 3.5 g K and 2.4 g Na) was calculated as described by US FDA (2013) using the following formula: