Effect of Extraction Methods on the Yield and Physiochemical Properties of Polysaccharides Extracted from Seaweed Available in Sri Lanka

Abstract

Agar, carrageenan and alginate are high valued seaweed polysaccharides, which are used as gelation and thickening agents in different food, pharmaceutical and biotechnological industries. The annual global production of the polysaccharides has recently reached 100,000 tons with a gross market value just above US$ 1.1 billion. In Sri Lanka although several seaweed species are available, there is no systematic study on comparison of method of extraction, yield and physicochemical properties of polysaccharides from seaweeds. Seaweed species Gracilaria edulis, Gracilaria verrucosa, Kapphaphycus alverazi and Sargussum wightti were collected from North and South coast of Sri Lanka. Gracilaria edulis and Gracilaria verrucosa were used for agar extraction with acid and alkaline treatments. Carrageenan was extracted from Kapphaphycus alvarezii using alkaline treatments. Three types of carrageenan (kappa, iota, lambda) were separated using freeze thawing, jelly pressing and alcohol precipitation methods respectively. For the extraction of alginates from Sargussum wightti samples were treated with acid and alkaline and hot and cold extraction methods were used. Some of the above physiochemical properties were compared with commercial available products.

Water-Soluble Polysaccharides from Ephedra alata Stems: Structural Characterization, Functional Properties, and Antioxidant Activity

“…Regarding the mineral composition of EAP extract, the results presented in Table 2 show that sodium was the most abundant mineral (223.2 mg/100 g), followed by calcium (197.85 mg/100 g), and then potassium (108.5 mg/100 g). As reported by Jayasinghe et al [26], the commercial agar contains a similar amount of Mg and K, whereas EAP present high levels of Na and Ca. The measurement of Aw shows that the EPA present an Aw of 0.37 ± 0.006, which is situated according to the map of stability in an area where the oxidation of lipids is low, non-enzymatic browning (Maillard reaction) is slow, and the enzyme activities are required to prevent the development of microorganisms.…”

“…This value was higher than that obtained for butylated-hydroxyanisole (BHA) (IC 50 = 0.4 mg/mL) used as the positive control. Despite the lower antioxidant activity compared with that of BHA, the obtained results indicated that EAP present an interesting natural antioxidant extract [26].…”

“…It should be noted that the extraction yield of polysaccharides is highly influenced by the extraction time and temperature, as well as the solid/liquid ratio [24]. The ash content of EAP was about 10.24% ± 0.24%, which was higher than some commercially available polysaccharides, such as agar and carrageenan, ranging from 2.5% ± 0.03% to 2.7% ± 0.031% [26]. Regarding the mineral composition of EAP extract, the results presented in Table 2 show that sodium was the most abundant mineral (223.2 mg/100 g), followed by calcium (197.85 mg/100 g), and then potassium (108.5 mg/100 g).…”

Influence of Seaweed Liquid Fertilizer on the Growth of Red Algae Gracillaria verrucosa under controlled conditions

“…This chelation process is highly associated with mannitol, a natural chelating agent. This chelating agent could provide micronutrients within the soil, revitalise the soil structure, and increase water reservoir capacity suitable for plants and crops [30].…”