Evaluation and Characterization of Alginate Extracted from Brown Seaweed Collected in the Red Sea

Abstract

Alginates are one of the most important compounds of brown seaweeds. These compounds are employed in the food area, because of their important rheological properties, such as viscosity, gelling, and stabilizing features and as dietary fiber source. In this study, five species of dominant brown seaweeds were collected in the Red Sea (Padina boergesenii, Turbinaria triquetra, Hormophysa cuneiformis, Dictyota ciliolata, and Sargassum aquifolium) so as to characterize the alginate yield and its properties. The analysis demonstrated differences in the alginate yield among the seaweeds. The highest yield of alginate was recorded in the species T. triquetra (22.2 ± 0.56% DW), while the lowest content was observed in H. cuneiformis (13.3 ± 0.52% DW). The viscosity from the alginates varied greatly between the species, whereas the pH varied slightly. The alginate exhibited a moisture content between 6.4 and 13.1%, the ash content ranged between 12.3 and 20% DW, the protein reached values from 0.57 to 1.47% DW, and the lipid concentration varied from 0.3 to 3.5% DW. Thus, the phytochemical analysis demonstrated that the extracted alginates can be safely applied in the food industry. Furthermore, the alginate yield reveals the potential application of these seaweeds as a nutraceutical raw source, which can be exploited by the food industry.

Recent developments in alginate-based adsorbents for removing phosphate ions from wastewater: a review

“… 65 Amongst these brilliant biopolymers, anionic alginate (Alg) is a collective family produced from algae and bacteria at a comparatively low cost. 66 Alg is a linear anionic polysaccharide that typically consists of 1,4-linked β- d -mannuronic acid and α- l -guluronic acid monomers. Alg was extracted for the first time in 1881 from kelp, then in the 1930s, it was extracted at a large scale from brown algae such as Laminaria digitata , Laminaria japonica , Ascophyllum nodosum , and Macrocystis pyrifera .…”

Alginate-Based Bio-Composites and Their Potential Applications

“…Therefore, it has a high absorption capacity, superior to those of hydro-colloids and hydro-cellulars [ 31 , 32 ]. It has been shown that alginates rich in mannuronic units have positive impacts on cicatrization, while other authors believe that this activity also depends on the level of purification of the alginate [ 33 , 34 ].…”

Algal Polysaccharides-Based Hydrogels: Extraction, Synthesis, Characterization, and Applications

“…The alginate extraction process involves several steps ( Figure 3 ) [ 36 , 57 , 58 , 59 ]. Chopped or ground algae materials are treated with acids to eliminate undesirable compounds through the proton exchanging reaction.…”

“…After hydrolysis, monomeric sugars and functional groups of polysaccharides can be identified and quantified [ 91 , 92 , 93 ]. Either 1H or 13C involved NMR systems are widely used to analyze polysaccharides presented in different algae species [ 36 , 59 , 94 , 95 , 96 , 97 ]. Moreover, 22 saccharides in raw honey, in the form of a monomer, dimer, or trimer, can be distinguished without pre-treatment using NMR based on the chemical-shift-selective filtration with total correlation spectroscopy sequence [ 98 ].…”

“…To estimate the presence of possible impurities in the extracted polysaccharides, some rapid qualitative assays for testing the existence of flavonoids, alkaloids, tannins, terpenoids, steroids, saponins, glycosides, phenols, and phlorotannins according to Evans and Trease [ 101 ] and Sofowara [ 102 ], are usually considered in characterization [ 59 ]. Those methods are all regarded as colorimetric analysis, determining the concentration of the analyte by comparing the color changes of the solution.…”