Extraction and physicochemical characterization of Sargassum vulgare alginate from Brazil

Abstract

Alginate fractions from Sargassum vulgare brown seaweed were characterized by (1)H NMR and fluorescence spectroscopy and by rheological measurements. The alginate extraction conditions were investigated. In order to carry out the structural and physicochemical characterization, samples extracted for 1 and 5h at 60 degrees C were further purified by re-precipitation with ethanol and denoted as SVLV (S. vulgare low viscosity) and SVHV (S. vulgare high viscosity), respectively. The M/G ratio values for SVLV and SVHV were 1.56 and 1.27, respectively, higher than the ratio for most Sargassum spp. alginates (0.19-0.82). The homopolymeric blocks F(GG) and F(MM) of these fractions characterized by (1)H NMR spectroscopy were 0.43 and 0.55 for SVHV and 0.36 and 0.58 for SVLV samples, respectively, these values typically being within 0.28-0.77 and 0.07-0.41, respectively. Therefore, the alginate samples from S. vulgare are much richer in mannuronic block structures than those from other Sargassum species. Values of M(w) for alginate samples were also calculated using intrinsic viscosity data. The M(w) value for SVLV (1.94 x 10(5)g/mol) was lower than that for SVHV (3.3 x 10(5)g/mol). Newtonian behavior was observed for a solution concentration as high as 0.7% for SVLV, while for SVHV the solutions behaved as a Newtonian fluid up to 0.5%. The optimal conditions for obtaining the alginates from S. vulgare were 60 degrees C and 5h extraction. Under these conditions, a more viscous alginate in higher yield was extracted from the seaweed biomass.

Sodium alginate from Sargassum wightii retards mortalities in Penaeus monodon postlarvae challenged with white spot syndrome virus

“…The average alginate yield from 5 extractions was 16.4 ± 1.4%, which compares favourably to yields of 16.9% reported for S. vulgare (Torres et al 2007) and of 21.1 to 24.5% for S. fluitans and 16.3 to 20.5% for S. oligocystum (Davis et al 2004). Somewhat higher alginate yields have been reported for S. fluitans (45%) and S. oligocystum (37%) (Davis et al 2003), and for other seaweed species quite varied yields of 3.3% for S. dentifolium, 12.4% for S. asperifolium and 17.7% for S. latifolium have been reported (Larsen et al 2003), suggesting that both species and extraction methods influence yields.…”

“…Protein, carbohydrate, lipid, fucose, total ash, acid-insoluble ash, water-soluble ash and sulphate contents of the sodium alginate extracts were also measured. Protein content (5.2%) was somewhat higher than low-viscosity (LV, 1.1%) and high-viscosity (HV, 1.0%) alginates extracted from S. vulgare (Torres et al 2007), but their moisture (14 and 16%) and total ash contents (2 and 1%) were comparable with the moisture (16%) and total ash (1.9%) contents of alginate powder prepared here from S. wightii, respectively. With regard to total carbohydrate (46.1%) and fucose (29.2%) contents determined for the S. wightii alginate, these varied considerably from those identified in alginates extracted from various algae harvested from the Egyptian Red Sea coast including Cystoseira trinode (74.9 and 11.6%, respectively), S. dentifolium (57.9 and 5.6%), S. asperifolium (32.2 and 4.2%) and S. latifolium (42.3 and 8.2%) (Larsen et al 2003).…”

“…The dried seaweed was ground using a mixer grinder and nonpowdered material was removed by using a sieve (Immanuel et al 2004). Sodium alginate was extracted from the ground seaweed by using a method modified from Torres et al (2007). Briefly, 100 g of seaweed powder was soaked in 2% formaldehyde in an air-tight flask for 24 h, the formaldehyde was filtered off and the solid residue was washed 2 to 3 times with distilled water.…”

Toxic concentrations of metronidazole to Microcystis protocystis

“…The mixture was stored for 2 hours in a refrigerator to separate the mucilage. The mucilage was separated by centrifugation at 4000 g for 20 minutes at 15 °C and then dried in an oven at 60 °C until a constant weight was reached (Torres et al, 2007). The raw yield was calculated as the ratio of the cyanobacteria dry biomass to the dry weight of the mucilage.…”

A review of extractions of seaweed hydrocolloids: Properties and applications

“…Inversely, more flexible gels may form due to the high amount of alginate-M blocks [29,30]. Some studies also reported that the presence of homopolymeric block structure, namely mannuronic acid blocks (FMM), guluronic acid blocks (FGG) and alternating blocks (FMG) can influence gelling properties of alginate too [31].…”