• Fisheries and Aquatic Sciences
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• v.16 no.2
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• pp.63-69
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• 2013

Shucked oysters were soaked in an equal weight of salt water and stored at $3^{\circ}C$ for 7 days. Changes in the free amino acid content of the whole body and in the adductor muscle were evaluated by a practical distribution method. With the exception of aspartic acid and tyrosine, no significant changes in free amino acids or ammonia were observed in whole-body shucked oysters during the storage period. In contrast, the majority of free amino acids in the adductor muscle decreased significantly. Most of these free amino acids were detected in considerable amounts in the surrounding salt water after 7 days of storage. Both the weight of the whole body and the salinity of the surrounding salt water decreased significantly during the storage period. These results suggest that free amino acids were eluted from the cutting surface of the adductor muscle and indicate that the free amino acid content per shucked oyster and in the adductor muscle, decreases during cold storage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.3
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• pp.259-266
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• 2011

To produce cupped oyster sprat consistently, we investigated the efficiency of nine settlement substrates using selective breeding of Pacific oyster Crassostrea gigas, with the goal of popularizing off-bottom culture on the west coast of Korea. We also compared the growth and survival of selectively bred sprat (diploid) with triploid sprat from an off-bottom culture system. Considering, the attachment rate and detachment efficiency, producing cupped oyster in a polypropylene gunny bag proved to be the most effective method. There were no differences in shell growth or total weight between the diploids from selective breeding and triploids from off-bottom culture for 5 months. However, the survival rate was 8 times higher in the diploids than the triploids. Transplanting sprat from selective breeding is one way to restore oyster farms and nurture off-bottom culture along the west coast.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.6
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• pp.766-771
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• 2016

The pacific oyster Crassostrea gigas has a desirable taste and flavor that differs from those of other fish and shellfish. In order to develop a high value-added product from individually quick-frozen oyster extract (IQFOE), we prepared an oyster granular flavor seasoning (OGS) from IQFOE and characterized its qualities. The OGS was prepared by granular molding and fluidized bed drying with inosine monophosphate (IMP, 0.1%), yeast extract powder (1.4%), tangle extract powder (0.6%), monosodium glutamate (MSG, 5.0%), microcrystalline cellulose (0.6%), lactose (27.5%), salt (33.0%), spray-dried IQFOE (22.5%) as a powdered materials, and IQFOE ($Brix\;25^{\circ}$, 7.0%), soy sauce (0.4%) and water (1.7%) as a liquid materials. The moisture, crude protein, pH and salinity of the OGS were 3.4%, 12.5%, 6.50 and 32.0%, respectively. Especially, the OGS revealed very higher amino-N content (1,856.0 mg/100 g) than that (1,291.2-1,610.2 mg/100 g) of other commercial flavor seasonings. In taste-active compounds, free amino acid contents was 1,359.0 mg/100 g, and major ones were glutamic acid, taurine, hydroxyproline, glycine, lysine, phosphoserine, proline in order. And OGS showed good organoleptic qualities for taste, odor and general preference compared with commercial flavor seasonings on a local market.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.05a
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• pp.266-266
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• 2002

• Proceedings of the Malacological Society of Korea Conference
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• 2002.11a
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• pp.21-22
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• 2002

• Proceedings of the Korean Aquaculture Society Conference
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• 2002.08a
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• pp.240.2-241
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• 2002

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1997.06a
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• pp.173.1-174
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• 1997

• Journal of Aquaculture
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• v.9 no.4
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• pp.445-452
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• 1996

Endogeneous activities of ${\beta}-galactosidase$-like enzyme in various tissues from several finfishes and shellfishes were examined by histochemical analysis based on X-gal staining and by fluorimetric measurement using 4-methylumbelliferyl-${\beta}$-D-galactoside (4-MUG). Species used in this study were 3 freshwater fishes, mud loach (Misgurnus mizolepis), common carp (Cyprinus carpio) and tilapia (Oreochromis niloticus) ; 3 marine fishes, olive flounder (Paralichthys olivaceus), stone flounder (Kareius bicoloratus) and marbled sole (Limanda yokohamae) ; and 4 shellfishes, abalone (Haliotis discus hannai), Pacific oyster (Crassoskra gigas), pearl oyster (Pinctada fucata martensii) and ark shell (Anadara broughtonii). The activities of ${\beta}-galactosidase$-like enzyme in all finfishes examined were significantly different among species, with the wide variations between tissues in a species. In general, the tissues such as kidney, intestine and liver were ones which showed the significantly higher values in 4-MUG fluorimetry and deeper staining patterns in X-gal analysis compared to other tissues. On the other hand, serum and muscle revealed the significantly lower activities than others did, regardless of species. Shellfishes were also found to have endogenous activities of ${\beta}-galactosidase$-like enzyme which were significantly varied depending on both species and organs in a species. Hepatopancreas from all shellfishes examined showed the deepest pattern in X-gal staining and also the highest value in 4-MUG analysis, while activities of ${\beta}-galactosidase$-like enzyme in adductor muscles and mantle muscles from all shellfish species in this study except Pacific oyster were negligible : Pacific oyster had the significant activity of this enzyme in muscle tissues. Putative endogenous lacZ fragment was amplified from both finfishes and shellfishes by polymerase chain reaction (PCR). The molecular size of PCR products was about 510 bp, and there was no difference in size among species examined.

• The Korean Journal of Malacology
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• v.32 no.4
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• pp.269-277
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• 2016

We examined the seasonal variation of the proximate, amino acid, fatty acid composition and glycogen contents of triploid Pacific oyster cultured in western coastal waters of Korea in 2015. The specimens were collected in February, May, August and November from off-bottom farming site. The lipid content was the highest in winter season (February, $2.10{\pm}0.06%$), the protein content was the highest in autumn season (November, $9.09{\pm}0.04%$) while the moisture and ash content was the highest in summer season (August, $86.00{\pm}0.12%$ and $2.67{\pm}0.03%$, respectively). The total amino acid contents was the highest in winter season (1,011.5 mg / 100 g), decreased gradually and was the lowest in summer season (486.7 mg / 100 g). The total amino acid composition was dominated by taurine, aspartic acid, glutamic acid, glycine and alanine. In the fatty acid composition, the two fatty acids, eicosapentaenoic acid and docosahexaenoic acid, which comprised that as much as 50% of the total fatty acid contents, were dominated during all season. The glycogen content was the highest in summer season ($1.26{\pm}0.03g$ / 100 g) although it was stable during the other season with the range of $0.69{\pm}0.04-0.86{\pm}0.01g$ / 100 g. Taken together, these results suggest that triploid pacific oysters have high commercial value not only in winter season but in summer season because they do not spawn and have high contents of glycogen comparing with those of diploid oyster in this period.

• Korean Journal of Environmental Biology
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• v.20 no.3
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• pp.268-275
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• 2002

Seasonal variation in reproductive condition of the Pacific oyster Crassostrea gigas was investigated from a suspended cultured oyster population in Gosung Bay, South Korea using histological techniques, Gametogenesis of oysters initiated in February when water temperature reached 11 to $13^\circ{C}$. Increase in oocyte size and the number resulting in follicle expansion was observed from March to May First spawning of oysters observed in mid Jun when the surface water temperature reached 22 to $25^\circ{C}$. Spawning activity of oysters extended from mid June to late September with two marked spawning peaks in June and August. Most oysters collected from October to December exhibited few residual eggs in packed follicles exhibiting a typical spent condition. No gametes were observed from December to February from oysters collected in the Bay. Gonadal development of oysters in the Bay seemed to follow a seasonal fluctuation in environmental conditions such as water temperature and food availability in the water column. Spawning of oysters in late June was in part associated with sudden drop in salinity due to vast amount of freshwater input in the Bay after the summer flooding. Sex ratio of oysters was 59.5% male and 39.8% female. Less than 1 percent (0.6%) of the oysters examined were hermaphrodite; few eggs were observed in testis.