• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.4
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• pp.226-231
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• 2005

To investigate the physical properties of sea tangle (Laminaria japonica) alginates, extracted by the Mexican process, the effects of extracting time and drying methods on intrinsic viscosities, MWs and DPs of alginates were examined. The MWs of alginates before and after dialysis decreased with increase of extracting time. The MW s before dialysis were lower than those after dialysis. The ash contents before dialysis decreased with increase of extracting time. After dialysis the ash contents of the alginates showed 10.4-10.9% of those, which were little affected by extracting time. In the ash composition after dialysis, the sodium content was 4.4 g/100 g, $90\%$ of total ash content. The ash contents, the intrinsic viscosities, the average molecular weight and the DPs of the alginates dried by AD before dialysis were higher than those by VF. The ash and uronic acid contents of alginates after dialysis showed $10.6-10.9\%\;and\l88.1-88.9\%$, respectively. But the intrinsic viscosities, the MWs and DPs of the alginates after dialysis gradually decreased by following dry methods. The decreased order was ADAD, ADVF, VFAD, VFVF. The coefficient of determination between MWs and DPs in the alginates having more than 300 kDa was 0.999.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.4
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• pp.340-345
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• 2003

In order to choose the manufacturing method for extracting alginates from sea tangle, Laminaria japonica, three methods were applied. In Method I, alginates were extracted with NaOH solution from sea tangle powder and extracted alginates were precipitated and converted to alginic acid by $CaCl_2$ and HCI solution. Then alginic acid was converted to sodium alginates with $Na_2CO_3$ solution. Sodium alginates were precipitated with methyl alcohol and were resolved with hot water and this step was repeated three times. Method II was same to Method I except final step including that sodium alginates were precipitated and washed with methyl alcohol three times. Method III included that sodium alginates were extracted with $Na_2CO_3$ solution from sea tangle powder then sodium alginates were precipitated and washed with methyl alcohol three time. Extracting time increased with Increasing extracted alginates amounts but increasing rates were below $0.4\%/h.$ Alginates amounts recovered by Method III showed above 2 times more to those by Method I and II. Extracting time increased with increasing ash amount of sodium alginates but increasing rates were below $0.1\%/h.$ and that of sodium alginates extracted by Method III showed higher value $(5\%)$ than those by Method I and II. In the sodium alginates prepared by Method III, the amount of ash in alginates dried by air was $34.4\%,$ that by vacuum freeze drying was $47.8\%.$ Extracting time increased with decreasing average molecular weight (MW) and degree of polymerization (DP) of sodium alginates, MW and DP of alginates prepared by Method III were higher than those by Method I and II In same extracting time. Extracting time increased with decreasing rate of apparent viscosity change (SAV) of alginates solution, and SAV of alginates prepared by Method III showed higher value than those by Method I and II in same extracting time. SAV of alginates dried by air was higher than that by vacuum freeze drying. Relating equation among SAV MW and DP were MW = 60.066 (SAV) -93.950, DP =309.760 (SAV) -485.084 and MW = 0.914 (DP)+0.213.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.1
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• pp.1-6
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• 2004

In preparing sodium alginates from sea tangle (Laminaria japonica) powder using the Mexican process, alkaline extraction, conversion to alginic acid and reversion to sodium alginates were used to increase purity. The effect of hot water treatment and dialysis on measuring the average molecular weight of sodium alginates were investigated. Intrinsic viscosity and average molecular weight of sodium alginates after dialysis were higher than those before dialysis. Average molecular weight of sodium alginates treated with hot water was higher than that without. Hot treatment has little effect on the ash content of sodium alginates. Ash content of sodium alginates before dialysis were $27-30\%$ those after dialysis were $10\%.$ After dialysis, Na content was highest $(89-91\%),$ K was $11-12\%,$ Ca was $1.9\%,$ and Mg was $0.05\%.$ Ash content of alginates had little effect on average molecular weight. SAV (slope of apparent viscosity) of alginates solution after dialysis showed higher values than before. SAV of the alginates with hot water treatment were higher than without treatment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.4
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• pp.313-317
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• 2006

To prepare oligouronic acids from high-molecular-weight alginates, sea tangle (Laminaria japonica) alginates were hydrolyzed at various pHs for 1 hr at 80$^{\circ}C$. The effects of hydrolysis pH (HpH) on the average molecular weight (AMW) and MW distribution ratios (DRs) in the hydrolyzed alginates were investigated. As HpH decreased, the DRs of the alginates with MW>500 kDa and MW=300-500 kDa decreased exponentially, while it increased exponentially for MW<50 kDa. For MW=100-300 kDa, DR increased exponentially as HpH fell from 5.0 to 3.5, and then decreased exponentially. Similarly, for MW=50-100 kDa, DR increased exponentially as HpH increased to 1.0 from 5.0, and then decreased exponentially. As HpH decreased, the MW cutoff size and AMW of alginates fraction with the highest DR were decreased. For HpH 4.5 and 5.0, the MW cutoff size with the highest DRs was MW=300-500 kDa; the DRs were 28.9 and 32.6%, respectively; and the AMW of both was about 400 kDa, for HpH 3.5 and 4.0, the cutoff size was MW=100-300 kDa; the DRs were about 28%: and the AMWs were both about 200 kDa. For HpH 3.0, the cutoff size was MW=50-100; the DR was 29.0%; and the AMW was 73 kDa. For HpH values below 2.0, the MW cutoff size with the highest DRs was MW<50 kDa, and all of the AMWs were below 28 kDa.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.4
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• pp.187-192
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• 2007

To prepare oligouronic acids from high-molecular-weight alginates prepared from sea tangle (Laminaria japonica), the alginates were hydrolyzed at various temperatures for 1 hr at pH 5.0. The effects of hydrolysis temperature $(H_{Temp})$ on the average molecular weight (AMW) and distribution ratio of MW (DR) in the hydrolyzed alginates were investigated. As $(H_{Temp})$ increased, the AMW of the alginates decreased exponentially; in addition the DR of the alginates with MW>500 kDa decreased exponentially, while the DR of those with MW=50-100 and MW<50 kDa increased exponentially. For the alginates with MW=300-500 and MW=100-300 kDa the DR increased exponentially until $H_{Temp}$ reached $80^{\circ}C$, and then decreased exponentially at above $80^{\circ}C$. AS $H_{Temp}$ increased, the MW cutoff size and AMW Of the alginates fraction With the highest DR both decreased. For $H_{Temp}<60^{\circ}C$, the MW cutoff size with the highest DR was MW>500 kDa; the DR was 39-67% and the AMW 1,000-1,300 kDa. For $H_{Temp}$ $80^{\circ}C$, the MW cutoff size with the highest DR was MW=300-500 kDa and the DR was about 33% and the AMW about 400 kDa. For $H_{Temp}\;100-121^{\circ}C$, the MW cutoff size with the highest DRs was MW=50-100 kDa, with a DR of 39-44% and an AMW of 70-80 kDa.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.1
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• pp.1-7
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• 1998

Uronate compositions and molecular weights of alginates from the four kinds of brown algae, sea mustard (Undaria pinnatifida), sea tangle (Laminaria japonica), gulf weed (Sargassum fulvellum), and seaweed fusiforme (Hizikia fusiforme), in regard with the harvesting season were investigated. Sea mustard contained the highest amount of alginates in the four kinds of brown algae. D-Mannuronic acid to L-guluronic acid (M/C) ratio of the alginates was high in order of seaweed fusiforme, gulf weed, sea mustard, and sea tangle, and especially in water-soluble alginate. Molecular weights of the alginates were greater with the growing period ranging in $4,500\~4,800\;kDa$ for sea tangle, $4,000\~4,200\;kDa$ for sea mustard, $3,300\~3,400\;kDa$ for seaweed fusiforme, and $3,000\~3,200\;kDa$ for gulfweed. In water-soluble alginate of sea mustard, M/G ratio was much higher in sporophyll than in midrib and blade.