Extraction, Antioxidant and Emulsifying Properties of Alginate from Brown Seaweed Sargassum ilicifolium

Alginate is one of the unique polysaccharides present in brown algae which are widely used in textile, paper, and food, pharmaceutical, biomedical and cosmetic industries. There are many seaweed species in the southern coast of our country (Iran). However, very few studies have been done so far on the extraction of alginate from these indigenous resources. Therefore, in the present study, alginate was extracted and purified from a brown seaweed Sargassum ilicifolium. Then, yield, molecular weight, antioxidant activity (DPPH radical scavenging activity and reducing power (FRAP), and emulsifying properties (emulsification indices) of the isolated alginate were evaluated. Furthermore, FT-IR spectra were used to identify the functional groups of the extracted alginate. Alginate extraction yield was 20.84±1.24% (based on seaweed dry weight). FT-IR results showed that the extracted polysaccharide was mainly sodium alginate. The molecular weight of the extracted alginate was 1865 kDa. The DPPH radical scavenging activity and the reducing power of the extracted alginate at 1 mg/ml were 18.17±2.03% and 0.155±0.004 (Abs), respectively. The extracted alginate was able to emulsify sunflower, corn, and canola oils. The highest and lowest emulsification indices (E24) were observed in sunflower and canola oils, respectively. Overall, the results of the present study showed that the alginate extracted from S. ilicifolium has medium antioxidant and high emulsifying properties.