• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.949-961
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• 2022

The purpose of this study is to build an oyster outlook model. In particular, by limiting oyster items, it was designed as a partial equilibrium model based on a panel analysis of a fixed effect model on aquaculture facilities. The model was built with a dynamic ecological equation (DEEM) system that considers aquaculture and harvesting processes. As a result of the estimation of the initial aquaculture facilities based on the panel analysis, the elasticity of the remaining facility volume in the previous month was estimated to be 0.63. According to Nerlove's model, the adjustment coefficient was interpreted as 0.31 and the adjustment speed was analyzed to be very slow. Also, the relative income coefficient was estimated to be 2.41. In terms of elasticity, it was estimated as 0.08% in Gyeongnam, 0.32% in Jeonnam, and 1.98% in other regions. It was analyzed that the elasticity of relative income was accordingly higher in non-main production area. In case of the estimation of the monthly harvest facility volume, the elasticity of the remaining facility volume in the previous month was estimated as 0.53, and the elasticity of the farm-gate price was estimated as 0.23. Both fresh and chilled and frozen oysters' exports were estimated to be sensitive to fluctuations in domestic prices and exchange rates, while Japanese wholesale prices were estimated to be relatively low in sensitivity, especially to the exchange rate with Japan. In estimating the farm-gate price, the price elasticity coefficient of monthly production was estimated to be inelastic at 0.25.

• Journal of The Geomorphological Association of Korea
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• v.17 no.2
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• pp.29-39
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• 2010

Climate change recently causes rapid rises in sea level in Baramarae intertidal area and the rises present several socio-economic impacts to the affected area. We have assessed the vulnerability of the region by the rise of the sea level. Using quantitative GIS method on multi-temporal satellite images, we have first estimated the elevation (Digital Elevation Model: DEM) of Baramarae intertidal area and hence we were possibly able to identify the flooded areas under the IPCC SRES scenarios. As sea level rises by 20cm, 30cm, 40cm, 50cm and 60 cm, the estimated flooded areas of the tidal flat are 68ha, 85ha, 103ha, 121ha and 139ha, respectively. The most affected area is the tidal flat in Gagyeongju Village (Gonam-li, Gonam-myeon, Taean, Chungnam), because it has not only lower altitude but also, perhaps more significantly smooth slope. The potential affected areas are currently populated by farming of oysters and short-necked clams and therefore the areas expect significant economic loss by rise of sea level.

• Journal of Microbiology and Biotechnology
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• v.33 no.9
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• pp.1162-1169
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• 2023

16S rRNA short amplicon sequencing-based microbiota profiling has been thought of and suggested as a feasible method to assess food safety. However, even if a comprehensive microbial information can be obtained by microbiota profiling, it would not be necessarily sufficient for all circumstances. To prove this, the feasibility of the most widely used V3-V4 amplicon sequencing method for food safety assessment was examined here. We designed a pathogen (Vibrio parahaemolyticus) contamination and/or V. parahaemolyticus-specific phage treatment model of raw oysters under improper storage temperature and monitored their microbial structure changes. The samples stored at refrigerator temperature (negative control, NC) and those that were stored at room temperature without any treatment (no treatment, NT) were included as control groups. The profiling results revealed that no statistical difference exists between the NT group and the pathogen spiked- and/or phage treated-groups even when the bacterial composition was compared at the possible lowest-rank taxa, family/genus level. In the beta-diversity analysis, all the samples except the NC group formed one distinct cluster. Notably, the samples with pathogen and/or phage addition did not form each cluster even though the enumerated number of V. parahaemolyticus in those samples were extremely different. These discrepant results indicate that the feasibility of 16S rRNA short amplicon sequencing should not be overgeneralized in microbiological safety assessment of food samples, such as raw oyster.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.6
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• pp.810-817
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• 2023

Oysters are a highly consumed seafood throughout Korea, but they have a short shelf life because they support rapid microbial growth due to their of high moisture content and fragile muscle tissue. We examined natural food additives including lactic acid bacteria fermentation powder, rosemary extract, and lemon juice for their ability to preserve raw oyster Crassostrea gigas quality. Samples were stored at 4℃, and microbiological and physicochemical analyses were conducted. Among the natural additives tested, lemon juice was the most effective. Lemon juice was thus applied at different concentrations (50-300 ppm) to quantitatively assess its effect on total viable cell count, pH, glycogen, soluble protein, and turbidity. 200 ppm was confirmed to be optimal, and is projected to extend shelf life by 2 days compared to the control group.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.1
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• pp.33-39
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• 2024

This study explores the utilization of common marine wastes, specifically seashells, such as oysters and cockles, as alternative fine aggregates in construction materials. The considered seashells were cleaned and pre-processed for use as a substitute for aggregate in mortar. Cement mortar specimens were prepared under different conditions, such as substitution ratios and the cleaning status of the seashells. The compressive strength of the mortars specimens was evaluated, and the solid and porous structures of each specimen were analyzed using microstructure analysis methods such as XRD, SEM, and micro-CT. The results confirmed that oyster and cockle seashells are composed of different calcium carbonate polymorphs, and their microstructural characteristics influence the mechanical properties of the cement mortar specimens.

• 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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.8
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• pp.1398-1406
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• 2004

To develop the new type of salt-fermented seafoods, the salt-fermented oysters in olive oil (product SO) were manufactured, and food components and quality characteristics of product SO were examined. The optimum processing condition for product SO is as follows. The raw oyster with no shell was washed off with 3% saline solution. Then dewatered, and dipped in the brine-salting solution made up with saturated saline solution and oyster sauce (2 : 1 v/v) mixture added 1% sodium erythorbic acid and 0.2% polyphosphate. After salt-fermentation it ripened by brine salting at 5$\pm$1$^{\circ}C$ for 15 days. Then dried at 15$^{\circ}C$ for 4 hours with cool-air, and packed in No. 3B hexahedron type can. Finally, poured with olive oil and seamed it by double-seamer. The moisture, crude protein, crude ash and volatile basic nitrogen contents of the product SO were 61.6%, 12.0%, 16.3% and 34.3 mg/100 g, respectively. In taste-active components of the product SO, total amount of free amino acids is 2,335.4 mg/100 g and it has increased by 50% overall during salt-fermentation 15 day. Taurine, glutamic acid, proline, glycine, alanine, $\beta$-alanine and lysine were detected as principal free amino acids. The contents of inorganic ions were rich in Na and K ion, while the amounts of nucleotide and its related compounds and other bases except betaine were small. From the results of this research, the product SO had a superior organoleptic qualities compared with conventional oyster product, and could be reserved in good conditions for storage 90 days at room temperature.

• Korean Journal of Food Science and Technology
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• v.45 no.2
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• pp.241-247
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• 2013

AOAC Mouse Bioassay Analysis (MBA) has been the gold standard for the analysis of paralytic shellfish poisoning toxin (PSP toxin) for more than 50 years. However, this method has inaccurate limit of quantification and cannot be used to determine toxic profiles. An HPLC method (PCOX) was optimized for Korean shellfish to establish an alternative or supplementary method for PSP analysis and was intended to be used for the official monitoring and regulation of food. The recovery rate of the PCOX method was 83.5-112.1% and the limit of quantification for total toxin was about $8.6{\mu}g$/100 g. A long-term comparison study showed a good correlation of the PCOX results with the AOAC MBA results: the correlation factors were 0.9534 and 0.9109 for oyster and mussel matrices, respectively. The PCOX method may be used as an alternative or supplementary method for AOAC MBA to monitor the occurrence of PSP and to analyze PSP toxin profile in oysters and mussels.

• Fisheries and Aquatic Sciences
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• v.4 no.4
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• pp.219-228
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• 2001

Surface sediments (0- 5 cm), mussels (Mytilus coruscus and M. edulis) and oysters (Crassostrea gigas) were sampled at 20 stations in Korean coast during a period of February to July 2000. Samples were analyzed for polycyclic aromatic hydrocarbons (PAHs) content using gas chromatography coupled to mass spectrometer detector (GC/MSD). The sediment $\sum PAH$ concentration varied from 7 to 1,214 ng/g dry weight and the level of carcinogenic PAHs of six species ranged from 1 to 563 ng/g dry weight in surface sediments. In organisms, the levels of $\sum PAH$ were in the range of 63-876 ng/g dry weight and the concentrations of carcinogenic PAHs of six species were in the range of 4-582 ng/g dry weight. The highest PAH concentrations in sediments and organisms were in samples from Station 5 in Pohang coast and Station 8 in Jinhae coast, respectively. $\sum PAH$ concentrations in sediments and organisms collected from Korean coast were slightly low or comparable to those in other countries. The contribution of ring aromatic groups to sum of 16 PAHs in sediments and organisms showed a similar pattern for most stations. In sediments, the predominant contributions were four and five ring aromatics like fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene and benzo[a]pyrene. In the organisms, four ring aromatics like fluoranthene, pyrene, benzo[a]anthracene and chrysene were predominant PAH species. Several molecular indices such as phenanthrene/anthracene, fluoranthene/pyrene and LMW/HMW ratio were used to identify the origin of PAH contamination in sediments. The results indicate that PAHs of Korean coast were mainly of pyro1ytic contaminants with slight petrogenic input. A high correlation within individual PAH compound in marine sediments was observed, while correlation in organisms showed a highly significant relationship for heavier molecular weight PAHs.

• Journal of Food Hygiene and Safety
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• v.20 no.3
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• pp.147-158
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• 2005

A food safety survey was conducted to assess the housewives' handling practices and consumption of potentially risky foods in family home. More than $40\%$ of the respondents wash their hands without soap or use their wash towels after contact with potentially risky foods such as meat, poultry, fish, shellfish, raw eggs, meat processed foods, raw fruits and vegetables. Over half of the respondents have consumed undercooked eggs without recognizing the potential health risk of consumption of raw eggs. $34\%$ of the respondents do not wash their hands after breaking raw eggs, indicating high risk of cross contamination while handling raw eggs. More than $60\%$ of the respondents just use running water to wash fresh fruits and vegetables. $78.9\%\;and\;45.2\%$ of the respondents have consumed sushi/sashimi or raw oysters, respectively in the past 12 months. The results of this study indicate the substantial risks of unsafe food-handling practice at the points of cross-contamination, cooling practices, storage time, and consumption of potentially risky foods at home. Considering the housewives' participation in school food service, development of food safety education program for the housewives is needed to promote safe handling practices of potentially risky foods.