• Journal of fish pathology
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• v.21 no.3
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• pp.241-246
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• 2008

The effects of temperatures on pearl oyster, Pincdata fucata were studied by evaluating some functional immune responses of the haemocytes. Water temperature is one of the most important factors in bivalve immune defense. Haemocytes comprise a primary line by inflammation, encapsulation and phagocytosis. These phagocytic abilities of haemocytes were observed in different temperatures. The number of the circulating haemocytes by migratory assay, phagocytic activities by MTT assay and reactive oxygen species production of haemocytes by CL assay were measured at different temperatures. Results showed that pearl oyster maintained at 20℃ and 25℃ displayed significantly higher values for all the measured immune parameters in comparison to maintained at 10, 15, and 30℃.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.10
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• pp.1484-1490
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• 2006

This study was carried out to prepare spaghetti sauce with adductor muscle of pearl oyster (SSAM) and to compare with commercial spaghetti sauce (CSS). From the results of organic acid, pH, hunter color value and sensory evaluation, the optimal addition ratio of adductor muscle of pearl oyster was 11% based for preparing SSAM and reasonable $F_0$ value was about 4 min for keeping storage of SSAM. The proximate composition of SSAM was 69.8% for moisture, 3.7% for protein, 4.2% for crude lipid and 3.4% for crude ash. SSAM was superior in sensory flavor and texture to CSS. There was, however, no significant difference (p<0.05) in sensory color between CSS and SSAM. The total amino acid content (3,033.4 mg/100 g) of SSAM was higher than that (2,305.7 mg/100 g) of CSS and the major amino acids were aspartic acid, glutamic acid, leucine and lysine. Calcium and phosphorus contents in SSAM were 48.5 mg/100 g and 27.1 mg/100 g, respectively. Calcium level based on phosphorous was 1.78, which was a good ratio for absorbing calcium. The free amino acid content and taste value of SSAM were 989.4 mg/100 g and 141.04 mg/100 g, respectively These results suggested that the major taste active compounds among free amino acid were glutamic acid and aspartic acid.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.6
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• pp.343-349
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• 2007

This study examined the effective utilization of pearl processing by-products. Three extracts of hot-water extract (WE), hydro-cooked extract (HE), and two-step enzymatic hydrolysate (EH) were prepared from pearl oyster muscle, and their characteristics were examined. The moisture, crude protein, volatile basic nitrogen (VBN), and amino-N contents were 97.5-98.0%, 0.5-1.3%, 2.1-4.9 g/100 mL, and 35.0-74.5 g/100 mL, respectively. EH had the lowest VBN and highest amino-N contents. In addition, EH had the highest yields. In terms of its functional properties, EH inhibited angiotensin-I converting enzyme ($IC_{50}$, 1.39 mg/mL) more strongly than the other extracts ($IC_{50}$, 4.17-7.95 mg/mL). The free amino acid contents of WE, HE, and EH were 661, 470 and 1,150 mg/100 mL, respectively. Major amino acids were taurine and glutamic acid. Major inorganic ions were Na, Mg, and Ca. Contents of taste compounds, such as free amino acids, inorganic ions, and quaternary ammonium bases, differed significantly according to the extract methods. Based on the results of chemical experiments and sensory evaluation, the quality of EH was superior to the other extracts, and EH is suitable for use in natural flavoring materials.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.987-988
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• 2012

• Proceedings of the Malacological Society of Korea Conference
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• 1999.11a
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• pp.12-12
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• 1999

• Development and Reproduction
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• v.11 no.2
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• pp.79-84
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• 2007

The freezing susceptibilities of two larval stages (D-shaped and umbo) of the pearl oyster (Pinctada fucata martensii) were evaluated by the electron microscopy (light, transmission electron and scanning electron). The morphological shapes were examined from each pre-frozen or frozen-thawed stage of the cryopreserved larvae in liquid nitrogen by using the cryoprotectant, dimethyl sulfoxide ($Me_2SO$) mixed with sucrose. Although a portion of the shell was damaged, the hinge and prodissoconch were intact and clearly visible after preservation in liquid nitrogen. In addition, the cytoplasm of the frozen-thawed larvae maintained the normal organelle integrities, e.g., endoplasmic reticula, lipid droplets, mitochondria, nucleus and microvilli. However, some of the frozen-thawed larvae showed irregularly arranged cilia, rough shell surfaces and round-lumped cilium heads. These results indicate that P. fucata martensii larvae are susceptible to freezing, at least at those two critical developmental stages (D-shaped and umbo), and suggest a new industrial investigation including reduction method of cell injury for preserving microbial starter cultures need to be developed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.6
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• pp.350-355
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• 2007

The optimal substrates and reaction flavoring conditions were examined to develop pearl oyster extract (POE) flavor using the Maillard reaction under a model system. The sugar for the Maillard reaction was glucose, and the amino acid was cysteine, with glycine as the reaction substrate. A three-dimensional response surface method was used to monitor the dynamic changes of the substrates during the Maillard reaction. To enhance the flavor of POE, a two-step enzymatic hydrolysate (Brix $20^{\circ}$) was reacted with the precursors (1:1, v/v). A 2:1:1 mixture of 0.4 M glucose:0.4 M glycine:0.4 M cysteine (v/v) was selected as a suitable reaction system for the reappearance of baked potato odor and boiled meat odor, and masking the shellfish odor. The two-step enzymatic hydrolysate and selected precursors were reacted in a high-pressure reactor to optimize the reaction parameters. The optimum conditions were 150 minutes at $120\;^{\circ}C$ and pH 7.0. The pH was the most critical factor for the response of the baked potato odor and masking the shellfish odor, while the reaction time affected the reappearance of the boiled meat odor.

• Journal of Aquaculture
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• v.1 no.1
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• pp.85-102
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• 1988

An experimental study on seedling production and wintering to develop pearl oyster, Pinctada fucata culture in Korea was carried out. from December 1986 to November 1988 in waters of Kori and of Seogwipo as wintering and of Eogu as culturing grounds. All pearl oysters as the sample were imported from Japan. The highest water temperature at Eogu was $23.6^{\circ}C$ in August and the lowest at Kori and Seogwipo were $13.2^{\circ}C$ and $14.0^{\circ}C$c in February, respectively, Phytoplankton was relatively plentiful but mortality of pearl oysters was $20.5\%$, which was twice at Seogwipo, due to high amount of suspended muds. It shows that Seogwipo is better wintering ground even though the amount of phytoplankton is lower than Kori. Average rates of pearl production after 6-months and 15-months period were $58.2\%$ and $48.3\%$ respecitively. Thickness of pearl layer and coating rate were also satisfactory. More than half of the pearls produced was so-called the pink-pearl, the best colour. About $10\%$ of them was the best quality. There were three peaks of D-shape larvae from July to September and it took about one month for D-shape larvae to become seed-shells. Settling was satisfactory and most of them settled at 1$\~$3 m layer and the best was 2 m-layer. Success of settling was supposed due to high water temperature and low precipitation than the normal year.

• The Korean Journal of Malacology
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• v.28 no.3
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• pp.245-254
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• 2012

This project analyzes distinct qualities of pearl cultured in Tongyeong by physical, chemical and optical test. The result is to provide scientific data for the value of pearl from Korean seawater. It divides one year pearl, which is used as a sample in the project, into white, natural blue and yellow gold colors, and then it has been divided into A, B and C based on the quality of the last results. A chemical experiment demonstrates that the higher quality has lower protein content of less than 10%. In another test called heavy metal content test, there is no big difference among classes. In the characterization of spectroscopy, it shows 280 nm peak indicated the conchiolin. It is clear that 407 nm, 430 nm and 460 nm peak are White group that are not in processed condition.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.1
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• pp.54-62
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• 2010

With the aim of developing and indoor overwintering technique for Pearl oyster, Pinctada fucata martensii, the metabolic rates of young oysters (52.4-83.0 mm in shell length) were measured for 2 weeks at water temperatures of 8, 10, 12, and $14^{\circ}C$. The filtration rate (FR) ranged 0 to $4.84\;L\;h^{-1}gDW^{-1}$ (mean, $0.02{\pm}0.06 $ to $3.12{\pm}1.45$), with significant changes observed over thme except for the case of a water temperature of $14^{\circ}C$. Respiration rate (R) ranged from 0 to $2.370\;mgO2\;h^{-1}gDW^{-1}$ (mean, 0 to $1.77{\pm}0.37$), with significant respiratory disorders observed at temperatures below $12^{\circ}C$; in contrast, the rate increased on the $14^th$ day of the experiment in the case of a temperature of 14$^{\circ}C$. No significant difference was observed among the different water temperatures in terms of excretion rate (E) or absorption efficiency (Abs.eff), except for a significant decrease in aerobic metabolism in the case of water temperature of $8^{\circ}C$. The estimated scope for growth (SFG) ranged from -9.1 to $126.9\;J\;h^{-1}gDW^{-1}$ (mean. $-4.1{\pm}2.6$ to $82.85{\pm}42.6$). A significant energy Joss was found at $8^{\circ}C$, with negative SFG observed throughout the experiment and a gradual energy decrease observed over time at water temperatures of $10^{\circ}C$ and 120C. However. SFG remained positive throughout the experiment in the case of $14^{\circ}C$. The estimated minimum energy requirement, assessed from energy expenditure, is $8.00-34.24\;J\;h^{-1}gDW^{-1}$ (mean, $17.67{\pm}6.17$). In conclusion, the lowest temperature suitable for indoor overwintering is above $14^{\circ}C$.