Biochemical Profiling of Gracilaria edulis Agar Waste for Aquaculture Applications | ||||
| Egyptian Journal of Aquatic Biology and Fisheries | ||||
| Article 227, Volume 29, Issue 4, July and August 2025, Page 3139-3156 PDF (616.14 K) | ||||
| DOI: 10.21608/ejabf.2025.449750 | ||||
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| Author | ||||
| Tadeo et al. | ||||
| Abstract | ||||
| Agar extraction from Gracilaria edulis generates approximately 65–75% solid waste. This study evaluated Seaweed Agar Waste (SAW) obtained through hot water extraction (T1) and alkaline pre-treatment (T2) methods for potential applications in aquaculture. Parameters analyzed included agar yield, SAW recovery, proximate composition, amino acid profile, and fatty acid composition. Agar yield was higher in T2 (77.46 ± 14.99 g; 28.17 ± 4.71%) compared to T1 (66.62 ± 14.04 g; 24.54 ± 6.41%). SAW recovery was 40.47 ± 4.76% for T1 and 36.42 ± 4.61% for T2. Proximate composition analysis revealed no significant differences in moisture, ash, fat, or fiber content between treatments. Carbohydrates constituted the predominant component, with higher concentrations in T2 (72.4 ± 2.16%) than in T1 (67.2 ± 1.00%). Conversely, crude protein content was higher in T1 (11.51 ± 0.64%) than in T2 (9.20 ± 1.01%). Total amino acid content was 20.72 ± 4.76 g kg⁻¹ DW in T1 and 25.66 ± 6.76 g kg⁻¹ DW in T2. Essential amino acids (EAAs) were more abundant in T1 (11.18 ± 1.61 g kg⁻¹) than in T2 (8.08 ± 3.19 g kg⁻¹), with respective EAA/Total AA ratios of 0.54 ± 0.05 (T1) and 0.31 ± 0.08 (T2). Fatty acid profiling showed saturated fatty acids (SFAs) as dominant in both treatments—40.76% in T1 and 38.93% in T2—followed by monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs). The principal PUFA in T1 was arachidonic acid (C20:4ω6), while eicosapentaenoic acid (EPA, C20:5ω3) predominated in T2. The ω-6/ω-3 ratio was markedly higher in T1 (8.90) compared to T2 (1.45). These findings highlight the nutritional potential of SAW—particularly its protein, amino acid, and fatty acid content—and support its prospective use as an aquaculture feed additive and biofertilizer. | ||||
| Keywords | ||||
| Agar extraction; Agar waste; Amino acid Antioxidant; Fatty acid; Proximate analysis | ||||
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