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Optimization of sodium alginate extraction conditions using a central composite design from the brown seaweed Sargassum angustifolium
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Akbar Norozi   , Mehdi Shamsaie1 , Laleh Roomiani , Houman Rajabi islami , Mehdi Raissy |
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Abstract: (28 Views) |
Introduction
Marine algae, with large size and wide variety of species, are marine ecosystems. They are cultivated both naturally and commercially in the coastal areas of the world. 25,000 tons of algae are produced worldwide each year and its economic value is about 6.5 billion, which appears to reach $ 1.07 billion by 2028 (Yang et al., 2025). Marine algae are mainly used as food in most Asian countries such as China, Japan, South Korea and North Korea, Indonesia, Philippines, Vietnam and Thailand, and for the first time in Japan in 1670 they were raised (Khan et al., 2024). Due to their high consumption in Asia, brown algae make up 47.3 percent of the world's cultivation level with 16.4 million tonnes (Nam et al., 2024; Radulovich et al., 2015).
Marine macroalgae are a sustainable raw material with antioxidant, antimicrobial, non-condensed, biodegradable and biological properties. The most important polysaccharide in algae cell is alginate (40 % dry weight), laminarin and fokoidan (Faidi et al., 2025). In algae, the percentage of alginate can reach up to 60 % dry weight. Alginates contain sodium, calcium, magnesium, barium and monomeric acid units D-mannuronic (M) and L-guluronic (G). Uronic acids are often organized in the forms of heteropolymer block (MG) or hemopolymer (MM or GG) (Fawzy et al., 2017).
Methodology
From the shallow and lower parts of the tide of the rocky beds of the Persian Gulf and the Oman Sea (Chabahar area), the S. angustifolium algae was carried out. The Persian Gulf and Oman Sea Atlas and Algae base platform data were used to confirm the species. The algae were washed with distilled water several times to remove impurities and algae sand. Then in the dry sun, they were powdered with a mill. Then, in polyethylene bags, they were transferred to the laboratory under 10°C (Fig. 1).
Figure 1: Sargassum angustifolium
Central Composite Design (CCD) using Response Surface Methodology (RSM) to optimize the process of extraction of sodium alginate in brown algae S. angustifolium by considering 3 factors or independent variables temperature (A), time (b) and pH (c) consisting of 19 points and 5 repeats at point the central was used with 19 treatments. In RSM it is selected for each domain variable. The third level as the central level or (0) is minimal and maximum (Table 1).
Table 1: Experiment design levels for independent variables using CCD
| Control factors |
Surface |
| -1 |
0 |
+1 |
| A |
Temperature (°C) |
40 |
65 |
90 |
| B |
Time (h) |
1 |
2.5 |
4 |
| C |
pH |
8 |
9 |
10 |
Results
The results of the CCD test plan with 19 repetitions are presented in Table 2 to evaluate the optimum parameters of sodium alginate extraction from S. angustifolium. As Table 2 shows, the actual and coded values of each factor and 19 experimental points include three repetitions of central points. Independent variables were the study of temperature (A), time (b) and pH (c). The second -degree polynomial equation shows the correlation between the independent variable and the responses. Multiple regression analysis and analysis of variance (ANOVA) were performed on experimental data and two multi -order multi -order equations were created in terms of encoded factors (Table 3). Second -degree equations for alginate efficiency and acidic amount were obtained as follows:
Alginate yield: 14.6029 + 2.0921 A + 1.0935 B + 9.3055 C - 0.41 AB + 1.6825 AC + 0.7995 BC - 1.15968 A2 + 0.0553247 B2 + 6.60732 C2
Uronic acid content: 14.0044 - 0.8655 A + 0.1275 B + 8.9599 C - 1.247 AB - 1.8205 AC - 0.413 BC - 4.59434 A2 + 1.19566 B2 + 4.29266 C2
Table 2: CCD design from RSM and the observed responses; Sodium alginate yield and uronic acids (%)
| Std |
Run |
Factor 1 |
Factor 2 |
Factor 3 |
Response 1 |
Response 2 |
| A: Temperature |
B: Time |
C: pH |
Sodium alginate yield |
Uronic acid content |
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°C |
h |
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% |
% |
| 10 |
1 |
90 |
2.5 |
9 |
15.501 |
8.981 |
| 18 |
2 |
65 |
2.5 |
9 |
13.407 |
17.208 |
| 9 |
3 |
40 |
2.5 |
9 |
12.104 |
10.070 |
| 2 |
4 |
90 |
1 |
8 |
12.184 |
7.167 |
| 11 |
5 |
65 |
1 |
9 |
12.778 |
14.435 |
| 13 |
6 |
65 |
2.5 |
8 |
11.652 |
9.278 |
| 7 |
7 |
40 |
4 |
10 |
26.902 |
27.881 |
| 14 |
8 |
65 |
2.5 |
10 |
31.487 |
27.547 |
| 4 |
9 |
90 |
4 |
8 |
10.559 |
6.489 |
| 3 |
10 |
40 |
4 |
8 |
11.183 |
6.122 |
| 15 |
11 |
65 |
2.5 |
9 |
16.318 |
12.608 |
| 17 |
12 |
65 |
2.5 |
9 |
14.277 |
13.027 |
| 8 |
13 |
90 |
4 |
10 |
34.648 |
18.743 |
| 12 |
14 |
65 |
4 |
9 |
17.257 |
16.196 |
| 1 |
15 |
40 |
1 |
8 |
9.528 |
4.035 |
| 19 |
16 |
65 |
2.5 |
9 |
12.825 |
11.413 |
| 16 |
17 |
65 |
2.5 |
9 |
14.75 |
15.304 |
| 5 |
18 |
40 |
1 |
10 |
23.689 |
25.223 |
| 6 |
19 |
90 |
1 |
10 |
31.435 |
23.296 |
Table 3: Analysis of variance (ANOVA) for CCD model of sodium alginate extraction yield and uronic acid content
| Source |
Sum of Squares |
df |
Mean Square |
F-value |
p-value |
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| Model of yield |
1123.64 |
9 |
124.85 |
77.75 |
< 0.0001 |
significant |
| A-Temperature |
43.77 |
1 |
43.77 |
27.26 |
0.0005 |
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| B-Time |
11.96 |
1 |
11.96 |
7.45 |
0.0233 |
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| C-pH |
865.92 |
1 |
865.92 |
539.28 |
< 0.0001 |
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| AB |
1.34 |
1 |
1.34 |
0.8375 |
0.3840 |
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| AC |
22.65 |
1 |
22.65 |
14.10 |
0.0045 |
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| BC |
5.11 |
1 |
5.11 |
3.18 |
0.1080 |
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| A² |
3.67 |
1 |
3.67 |
2.29 |
0.1646 |
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| B² |
0.0084 |
1 |
0.0084 |
0.0052 |
0.9440 |
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| C² |
119.29 |
1 |
119.29 |
74.29 |
< 0.0001 |
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| Residual |
14.45 |
9 |
1.61 |
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| Lack of Fit |
7.20 |
5 |
1.44 |
0.7952 |
0.6046 |
not significant |
| Pure Error |
7.25 |
4 |
1.81 |
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| Cor Total |
1138.09 |
18 |
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| Model of uronic content |
934.89 |
9 |
103.88 |
36.12 |
< 0.0001 |
significant |
| A-Temperature |
7.49 |
1 |
7.49 |
2.60 |
0.1410 |
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| B-Time |
0.1626 |
1 |
0.1626 |
0.0565 |
0.8174 |
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| C-pH |
802.80 |
1 |
802.80 |
279.16 |
< 0.0001 |
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| AB |
12.44 |
1 |
12.44 |
4.33 |
0.0673 |
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| AC |
26.51 |
1 |
26.51 |
9.22 |
0.0141 |
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| BC |
1.36 |
1 |
1.36 |
0.4745 |
0.5083 |
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| A² |
57.68 |
1 |
57.68 |
20.06 |
0.0015 |
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| B² |
3.91 |
1 |
3.91 |
1.36 |
0.2738 |
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| C² |
50.35 |
1 |
50.35 |
17.51 |
0.0024 |
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| Residual |
25.88 |
9 |
2.88 |
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| Lack of Fit |
4.35 |
5 |
0.8703 |
0.1617 |
0.9643 |
not significant |
| Pure Error |
21.53 |
4 |
5.38 |
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| Cor Total |
960.77 |
18 |
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Discussion and conclusion
Optimizing the process conditions to achieve maximum efficiency and uronic acid amount can be obtained by analyzing multiplication using utility function. Under the experimental conditions, the projected extraction efficiency of sodium alginates was 33.54 % and 0.956, respectively. High desirability (0 ≤d ≤ 1) indicates better accuracy of independent variables in optimization. Both responses were empirically approved under optimal parameters, indicating that the model is sufficient to predict these responses and are comparable with other researchers: Sargassum natans 23 %, Sargassum vulgare 17 %, Padina gymnospora 16 %, Padina antillarum 22 %, Laminaria digita 29 %, Macrocystis pyriffra 26 % (Rhein-Knudsen et al., 2017), Sargassum vulgare 40 % (Sari-chmaysme et al., 2016), 19% Sargassum natans (Mohammed et al., 2018). Kanagesan et al. (2022) gained the efficiency of 13.55 % alginate by alkaline with 3 % carbonate extraction. Changes in alginate extraction efficiency among various studies, including the current study, may be due to differences in sargassum species, growth conditions, or extraction conditions (Khan et al., 2024). The efficiency of the extracted alginate is different among the brown marine algae, as these algae have physiological and metabolic processes that allow it to produce different metabolites. The concentration of nutrients in the environment directly affects the amount of polysaccharide in different metabolites. The production of polysaccharides is influenced by several factors such as species, age, sampling time and extraction method (El-Sheekh et al., 2024).
Conflict of interest
The authors declare no conflict of interest.
Acknowledgment
The authors would like to thank the Islamic Azad University, Ahvaz Branch for arranging the experimental samples. |
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| Keywords: Sodium Alginate, Uronic Acid, Algae, Sargassum angustifolium |
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Full-Text [PDF 1502 kb]
(2 Downloads)
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Type of Study: Research |
Subject:
بيوتكنولوژي و فرآوري هاي شيلاتي
Received: 2025/02/25 | Accepted: 2025/07/1
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