| Abstract | Nutrient composition, total phenolic content (TPC) and in vitro protein digestibility (IVPD) of wild and cultivated seaweeds were determined. Seaweeds had a high range of protein (7–31 % of dry weight (DW)), lipid (3–13 % DW), carbohydrate (32–60 % DW), ash (9–45 % DW) and energy (10–18 MJ kg⁻¹ DW). Seaweeds had favourable amino acid (AA) profiles with moderate (0.77–0.86) to high (0.93–1.07) essential AA indices. Major minerals and trace elements included calcium (0.1–1.1 % DW), magnesium (0.2–0.8 % DW), phosphorous (0.1–0.6 % DW), potassium (2.1–4.6 % DW), sodium (1.1–3.9 % DW), sulphur (0.4–6.5 % DW), copper (1–21 mg kg⁻¹ DW), iron (26–945 mg kg⁻¹ DW), manganese (3–191 mg kg⁻¹ DW) and zinc (28–74 mg kg⁻¹ DW). Red seaweeds contained low TPC (4–5 mg gallic acid equivalents (GAE) g⁻¹ DW) whereas most brown seaweeds contained moderate (11–18 mg GAE g⁻¹ DW) to high levels (47–59 mg GAE g⁻¹ DW). IVPD was mid-range (82–87 %) for Saccharina latissima, Palmaria palmata (W), Palmaria palmata (M-S), Chondrus crispus, Meristotheca papulosa and Sarcodiotheca gaudichaudii and lower (79 %) for Ascophyllum nodosum, Fucus vesiculosus and Alaria esculenta. Despite relatively good AA profiles, estimated digestible protein (DP) levels for seaweeds were generally low (<15 % DW) with exception of moderate levels (16–24 % DW) for P. palmata (W), P. palmata (M-S) and S. gaudichaudii. A highly significant inverse correlation (r = −0.81, R² = 0.83, P < 0.001) was found between TPC and IVPD of seaweeds (IVPD = 89.198 × TPC⁻⁰.⁰³⁵). The following species-specific nitrogen-to-protein conversion factors were determined: P. palmata (W), 6.28; P. palmata (M-S), 4.54; C. crispus, 4.85; S. gaudichaudii, 5.55. |
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