# Evaluation and Characterization of Alginate Extracted from Brown Seaweed Collected in the Red Sea
## 2 Materials and Methods
### Biochemical Composition of the Extracted Sodium Alginate  
The biochemical composition of the sodium alginate extracted from different brown seaweeds is given in Table 5. The seaweed carbohydrate yields were similar among the analyzed species (around 80%)--the only species presenting a lower yield was _P. boergesemii_ (76.3 \(\pm\) 0.4% DW). The total lipid, protein, and ash contents of the extracted sodium alginate were highly significantly varied among species (_p_ = 0.001). The sodium alginate of _D. ciliulata_ showed the highest protein content (1.47 \(\pm\) 0.2% DW) and the highest lipid content (3.5 \(\pm\) 0.1% DW), whereas the lowest protein content was recorded in _T. triquetra_ (0.56 \(\pm\) 0.1% DW). The minimum lipid content was found in _P. boergesemii_ (0.3 \(\pm\) 0.09% DW). On the other hand, the sodium alginate of _P. boergesemii_ showed the highest ash content (20 \(\pm\) 1.2% DW). Thus, the alginate obtained had heterogeneity that was derivated from the seaweed species' in protein and lipid content, although the carbohydrate yield (alginate) was very high. The alginate characterization demonstrates that these five unexploited and unstudied seaweeds have a similar alginate chemical characterization. However, _T. triquetra_ demonstrated the highest average yield of sodium alginates (22.2 \(\pm\) 0.56% DW), followed by _D. ciliulata_ (20.2 \(\pm\) 1.1% DW), with descending order of _T. triquetra_ > _D. ciliulata_ > _S. aquifolium_ > _P. boergesemii_ > _H. cuneiformis_ (Table 5). In the literature, these seaweeds have scarce information regarding their alginate yield and characterization. Only _S. aquifolium_ and _H. cuneiformis_ have data relative to the alginate yield. In _S. aquifolium_, the alginate yield was lower when compared with the same species collec \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Species** & **F\({}_{\mathbf{G}}\)** & **F\({}_{\mathbf{GG}}\)** & **F\({}_{\mathbf{M}}\)** & **F\({}_{\mathbf{MG}}\)** & **F\({}_{\mathbf{GM}}\)** & **F\({}_{\mathbf{MM}}\)** & **M/G** & **\(\eta\)** \\ \hline _P. boergesemii_ & 0.08 & 0.03 & 0.92 & 0.05 & 0.05 & 0.88 & 12.30 & 0.66 \\ _T. triquetra_ & 0.15 & 0.14 & 0.85 & 0.01 & 0.01 & 0.85 & 5.80 & 0.06 \\ _H. cuneiformis_ & 0.10 & 0.09 & 0.90 & 0.01 & 0.01 & 0.89 & 9.11 & 0.14 \\ _D. ciliulata_ & 0.12 & 0.08 & 0.88 & 0.05 & 0.05 & 0.83 & 7.07 & 0.42 \\ _S. aquifolium_ & 0.07 & 0.01 & 0.93 & 0.06 & 0.06 & 0.87 & 12.96 & 0.88 \\ \hline \hline \end{tabular} \(\mathrm{F_{G}}\)—gluturonic acid ratio; \(\mathrm{F_{GG}}\)—gluturonic homopolymeric blocks; \(\mathrm{F_{FM}}\)—thermuronicic block’s guluronic acid ratio; \(\mathrm{F_{MG}}\)—thermuronic homopolymeric blocks’s guluronic/campuronic acid; \(\mathrm{F_{MM}}\): mannuronic homopolymeric blocks; M/G—mannuronic/guluronic acid ratio; \(\mathrm{\eta}\)—relative abundance of homopolymeric blocks MM and GG \(\eta\) = 1 for completely random cases and \(1\) \(\mathrm{<}\)\(\mathrm{<}\)\(\mathrm{<}\) 2 for alternate-like cases MG and GM.  
\end{table} 
Table 4: Compositional data of the alignates extracted. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Compound** & _P. boergesemii_ & _T. triquetra_ & _H. cuneiformis_ & _D. ciliulata_ & _S. aquifolium_ \\ \hline Carbohydrate & 76.3 \(\pm\) 0.4 b  & 81.2 \(\pm\) 0.1 a  & 80.5 \(\pm\) 0.3 a  & 82.5 \(\pm\) 0.2 a  & 83.1 \(\pm\) 0.1 a  \\ Protein & 0.86 \(\pm\) 0.2 b  & 0.57 \(\pm\) 0.1 b  & 0.68 \(\pm\) 0.5 b  & 1.47 \(\pm\) 0.2 a  & 0.952 \(\pm\) 0.1 b  \\ Lipid & 0.3 \(\pm\) 0.1 c  & 1.3 \(\pm\) 0.1 b  & 1.6 \(\pm\) 0.2 b  & 3.5 \(\pm\) 0.3 a  & 0.6 \(\pm\) 0.1 c  \\ Ash content & 20 \(\pm\) 1.2 a  & 15.5 \(\pm\) 2.2 b  & 15.5 \(\pm\) 2.2 b  & 16.3 \(\pm\) 1.6 b  & 12.3 \(\pm\) 0.8 c  & 15.2 \(\pm\) 0.9 b  \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Biochemical composition of the extracted sodium alginate. Island, Indonesia) (range: 24.26 \(\pm\) 0.08 to 39.01 \(\pm\) 0.03% DW) [54]. The alginate yield in _H. cuneiformis_ was lower in our study when compared with the study of [PERSON] et al.