Extraction and characterisation of alginate from brown seaweeds (Fucales, Phaeophyceae) collected from Port Dickson, Peninsular Malaysia

Abstract

Four species of brown seaweeds, namely Sargassum baccularia, Sargassum binderi, Sargassum siliquosum and Turbinaria conoides, harvested from Port Dickson, Negeri Sembilan, Malaysia were analysed for ash content, alginate yield and alginate properties. Seaweeds calcined at 450°C were found to have low amount of non-combustible residue as these were not contaminated by calcareous animals. Alginate was extracted from these seaweeds by two methods: hot and cold. In the hot method, the storing time was 3 h and the processing temperature was 50°C, whilst in the cold method, the sample was stored overnight at room temperature. Higher yield of alginate was obtained by the hot method compared to the cold method, but alginate extracted by the cold method gave higher molecular weight. In the hot method, 49.9% of alginate was extracted from S. siliquosum, followed by T. conoides (41.4%), S. binderi (38.9%) and S. baccularia (26.7%). Alginate extracted from T. conoides has an average molecular weight, M w , of 8.06×10 5 g mol −1 , whereas alginate from S. siliquosum was the lowest in M w (4.81× 10 5 g mol −1 ) when the extraction was done at room temperature. Alginate extracted from S. baccularia was found to be very heat-sensitive. Its M w has dropped more than 83%, from 7.52×10 5 to 1.23×10 5 g mol −1 , when the extraction temperature was raised. The effect of heat on the extent of depolymerisation of the alginate molecule of the other three brown seaweed species was less significant, with decrease in molecular weight ranging between 13% and 16%.

A review of extractions of seaweed hydrocolloids: Properties and applications

“…However, this treatment may cause depolymerization of alginate, which consequently decreases the alginate rheological properties (i.e. viscosity) and their commercial preferences taking into account that the industrial use of alginate mainly depends on these properties [68,72]. In spite of that, the quality of alginate might also be determined based on their functional properties (i.e.…”

“…which need to be taken into account as it can synchronously influence the extraction yield and rheological properties (i.e. viscosity and molecular weight) of alginate [39,68,69,72]. Besides formaldehyde, acid pre-treatment and alkali extraction, recovering (filtration) ( Table 4) is another crucial process for alginate production.…”

Preparation and Characterization of Porous Hydroxyapatite and Alginate Composite Scaffolds for Bone Tissue Engineering

“…Once harvested, the seaweed specimens were washed with water to remove dirt, air dried and stored in the shade at a ventilated site. Extraction of alginate was carried out using the method reported in previous studies [24,31].…”

“…Because large pores may be suitable for cell attachment in the inner parts of a scaffold, the HA/alginate scaffold may offer an alternative for bone tissue engineering. Alginate [(C 6 H 7 O 6 Na) n ], a natural resource of polysaccharides derived from brown seaweed, composed of 1-4-β-D mannuronic and L-guluronic acids contains a large number of pendant carboxylic acid groups, which provide sites for heterogeneous mineral nucleation [23][24][25]. Alginate is highly hydrophilic that can form stable hydrogels in the presence of certain divalent cations, such as Ca2+, Mg2+, Fe2+, Ba2+, or Sr2+.…”

Effect of Extraction Methods on Characteristic of SodiumAlginate from Brown Seaweed Sargassum fluitans

“…Kadar abu yang rendah dapat disebabkan oleh adanya sedikit residu yang tidak mudah terbakar seperti mineral dalam rumput laut. Rendahnya kadar abu juga menunjukkan bahwa sampel tidak terkontaminasi oleh organisme berkapur yang tidak dapat hilang ketika pencucian (Chee et al 2011).…”