• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.4
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• pp.335-342
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• 2017

Oysters Crassostrea gigas are a globally popular shellfish for human consumption. As filter-feeding bivalve mollusks, oysters may harbor many microorganisms and chemicals that could pose potential human health risks. The objective of this study was to investigate the suitability of cultured oysters for raw consumption or use in seafood products by measuring concentrations of harmful microorganisms and chemicals in their flesh. Microbial concentrations in cultured oysters were found to be: $1.0{\times}10^2-6.0{\times}10^4CFU/g$ (viable cell counts), not detected $(ND)-5.4{\times}10^3CFU/g$ (coliform bacteria), $ND-1.3{\times}10^2CFU/g$ (E. coli), and $ND-4.6{\times}10^3CFU/g$ (Vibrio parahaemolyticus). Other pathogenic bacteria, including Enterohemorrhagic E. coli (EHEC), Listeria monocytogenes, Staphylococcus aureus, and Salmonella spp., were not detected in any samples. Heavy metal concentrations of cultured oysters were ND-0.239 mg/kg (total mercury), ND-1.091 mg/kg (lead), ND-0.968 mg/kg (cadmium). The concentrations of benzo(a)pyrene ranged from $0.280-0.880{\mu}g/kg$. Paralytic shellfish poison ranged from ND-0.58 mg/kg, while diarrhetic shellfish poison was not detected. No radioactivity was detected. These results suggest that oysters intended for raw consumption or use in seafood products should be subjected to chemical and biological controls.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.10
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• pp.1475-1483
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• 2006

This study was carried out to examine the optimum processing conditions of seasoned semi-dried oyster, and to investigate its food component characteristics. Three types of semi-dried oyster were prepared: semi-dried oyster prepared without seasoning and coating (C), seasoned semi-dried oyster without coating (S) and seasoned semi-dried oyster coated with alginate (SA). SA was high in moisture (48.6%), while low in lipid (2.8%), and crude protein (25.9%) compared to those of C and S. Hardness and sensory scores of SA were $209.8g/cm^2$ and $3.9\sim4.5$ points, respectively. Total amino acid content (24,299 mg/100 g) of SA was lower than that (27,181 mg/100 g) of C, and the major amino acids were aspartic acid, glutamic acid, leucine and Lysine. The major fatty acids of SA were 16:0 (25.5%) as saturates and EPA (23.5%) and DHA (9.3%) as polyenes. Calcium and phosphorus contents of SA were 42.6 mg/100 g and 245.5 mg/100 g, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.1
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• pp.24-32
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• 1984

In order to process instant foods which hold appropriate moisture contents and soft texture, four kinds of retort pouched seasoned-oyster products were prepared as control, seasoned products, solid smoked and liquid smoked product after seasoning and their processing conditions and quality stability during 100 days of storage were investigated. The optimum processing conditions of retort pouched seasoned-oyster product were as follows ; namely, raw oyster was seasoned at $105^{\circ}C$ for 10 min with seasoning solution prepared from sugar, sorbitol, salt, monosodium glutamate and 5'-ribonucleotide and then dipped for 30 seconds in Smoke-EZ solution(Alpha Foods Co., Ltd.) after predried for 30 min in hot-air drier. After. smoking, the seasoned and liquid smoked oyster was dried at $40-42^{\circ}C$ for 2.5 hours, vacuum packed in plastic film bag, and sterilized in a hot water circulating retort at $120^{\circ}C$ for 16 min. Comparing their quality before and after sterilization, TBA value of all the products after sterilization slightly decreased and among texture profiles hardness, toughness and chewiness slightly decreased, while elasticity and cohesiveness were rarely changed. Color value (a value) of the product treated with solid smoke or liquid smoke increased after sterilization. During storage pH, VBM and water activity of all products changed little and TBA values of the solid smoked product and liquid smoked one were lower than that of the others. Viable cell count was negative and texture changed little during storage. As for color difference during storage, green meat appeared on the surface of control and seasoned product after 15 days storage, while the masking of green meat could achieved by solid and liquid smoking treatment. And liquid smelling treatment was more effective than solid smoking. As a conclusion, retort pouched seasoned-oyster product treated with liquid smoke kept their good quality during 100 days storage and it seemed to be consumed as one of the instant foods which hold appropriate moisture contents and soft texture.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.1
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• pp.11-15
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• 1977

Brownish discoloration develops very rapidly in the storage of dried oyster. This undesirable browning is mainly caused by the series of reactions of sugar-amino condensation, enzymatic oxidation of tyrosine and/or the oxidative rancidity of lipids in the tissue of oyster. Sulfites are commonly used as inhibitors for Maillard type browning reactions in agricultural products. The inhibitory effect of sulfite treatment on canned oysters was also confirmed in some investigations. The results suggested that sulfites not only work on blocking tile amadori rearrangement but also on the reduction of free tyrosine which retards the progress of enzymatic oxidation of tyrosine tyrosinase. In this paper, the effect of sodium sulfite treatment on the reduction of reducing sugar and free tyrosine as a function i)f browning inhibition in oyster was tested and other treatment with glucose-oxidase and yeast were also applied. In preparation of samples, fresh oysters were soaked in sodium sulfite solution by various concentration for different treating times, washed in running water to remove the sulfite residue, and finally dried in the shade. In the result, the treatment of sodium sulfite was certainly effective on the reduction of both free tyrosine and reducing sugars in fresh oyster. The best results were obtained by the treatment of 0.5M sodium sulfite solution for 60 minutes each for soaking and washing. Treatment with, glucose-oxidase and yeast solutions, however, did appear somewhat effective but it required so much time for a certain effect that it seemed not practically applicable.

• Journal of the Korean Applied Science and Technology
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• v.29 no.4
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• pp.599-609
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• 2012

The objective of this research is to reuse and recycle the oyster shell wastes as a useful of antioxidant beads for foodstuff preservation through the treatment of oyster shell and seaweed pulp. This research is divided into two parts. In the first, designing and preparation of pilot scale condition was accomplished. The second part dealt with establishing the optimized manufacturing condition for [A],[B],[C-a],[C-b] compounds, and analyzing these products. The pilot scale preparation was composed of modify synthesized seaweed pulp / Cl-starch and it's various bead form were prepared with various weight ratios using polar protic solvents. In addition, with increased seaweed pulp content in the blends, antibacterial property values of seaweed pulp/Ag-oyster shell blend was decreased, however, the antioxidant and bead's solidity properties increased.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.677-683
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• 2017

The Korean aquaculture industry was generally began in the 1970s and has gradually increased. Now, the number of households is about 7,068 and the scale of an aquaculture farm is about 248,014 ha; the value of all production in the industry is estimated to be about 1602.2 billion won. The aquaculture industry is very valuable and important for future food resources. However, the aquaculture industry was damaged by several marine ecological disturbance causing organisms. The Ascdiella aspersa colonized on the shell of scallop and then scallops were detached from rope. The patterns of damage in the aquacultures were observed in Tongyeong (oyster), Geojedo (oyster), and Gangneung (sea squirt) in June, 2017, as well as in Tongyeong (oyster) in November, 2017 by SCUBA divers. The species Halichondria bowerbanki, Bugula neritina, Mytilus galloprovincialis, Balanus amphitrite, Ascidiella aspersa, Ciona intestinalis, Didemnum sp, Styela plicata in Tongyeong, M. galloprovincialis, A. aspersa, C. intestinalis, D. vexillum, S. plicata in Geojedo, and M. galloprovincialis in Gangneung were all usually found in their farms. The marine ecological disturbance causing organisms gave rise to a reduced number of aquaculture products.

• Food Science of Animal Resources
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• v.38 no.6
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• pp.1246-1252
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• 2018

This study was conducted to investigate the effects of the addition levels of a phosphate replacer blend in ground pork sausages. The phosphate replacer consisted of 0.2% oyster shell calcium powder, 0.3% egg shell calcium powder, and 0.25% whey protein concentrate. Depending on the presence or absence of synthetic phosphate and the addition level of phosphate replacer, the following products were processed: control (+) (0.3% phosphate), control (-) (non-phosphate), 20AL (20% replacer), 40AL (40% replacer), 60AL (60% replacer), 80AL (80% replacer), and 100AL (100% replacer). The pH values of pork sausages increased (p<0.05) with increasing addition level of the phosphate replacer. When more than 40% of the phosphate replacer was added to pork samples (40AL, 60AL, 80AL, and 100AL), cooking loss was significantly reduced compared to both the control (+) and control (-). However, no significant differences were observed in the moisture content and CIE $L^*$ values between the controls and the treatments with a phosphate replacer. The control (+) and 100AL treatment had the highest (p<0.05) hardness, but the samples with the phosphate replacer were not significantly different in cohesiveness and springiness from the control (+). As addition level increased, the gumminess and chewiness of the products with the phosphate replacer increased, which were lower than those of the control (+). Therefore, more than 40% of a phosphate replacer may possibly substitute synthetic phosphate to improve product yields in ground pork sausages, although further studies may be needed for improving the textural properties of the final products.

• Journal of agriculture & life science
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• v.46 no.3
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• pp.59-68
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• 2012

This study was conducted to investigate the economic analysis of fermented diet made of agricultural and marine by-products such as, dropped apples, persimmon shells, mushroom (Flammulina velutipes) by-products, king oyster mushroom by-products and brewer's grain in Berkshire or crossed pigs. The daily diet cost were decreased by 2.16~3.44%, 3.83~13.35% and 7.47~41.61% when fermented dropped apples diet, fermented persimmon shells diet and fermented mushroom (F. velutipes) by-products diet were fed to Berkshire pigs. The daily feed cost was also decreased by 1.59~4.05% and 59.09~66.90% when fermented king oyster mushroom by-products diet and fermented brewer's grain diet were fed to crossed pigs. Carcass prices were increased by 3.09%, 1.20~3.40% and 1.13% when 2% fermented dropped apples diet, fermented persimmon shells diet and 0.5~1.0% fermented mushroom (F. velutipes) by-products diet were fed to Berkshire pigs. Carcass prices were increased by 2.87~4.19% and 41.31~49.14% when fermented king oyster mushroom by-products diet and fermented brewer's grain were fed to crossed pigs. Therefore, fermented agro by-products diet of dropped apples, persimmon shells, king oyster mushroom, mushroom (F. velutipes) and brewer's grain was expected to improve swine farms income due to decreased diet cost and increased carcass prices in Berkshire pigs or crossed pigs.

• Journal of Environmental Health Sciences
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• v.6 no.1
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• pp.43-46
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• 1979

Author studied on the distribution of Vibrio parahaemolyticus the sea water and shellfish, oyster, sea squirt in the protof Busan in 1978. The results obtained were as follows: The numbers of Vibrio parahaemolyticus isolated from the sample of sea water and marine products 80 cases were 11 strains (13.8%).

• Korean Journal of Environmental Biology
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• v.22
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• pp.63-70
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• 2004

Tributyltin (TBT) and its degradation products, dibutyltin (DBT) and monobutyltin (MBT) were quantitatively determined in surface sediments and two molluscan species, Pacific oyster (Crassostrea gigas) and rock shell (Thais ctavigera), from Gwangyang Bay, Korea. Butyltin compounds were detectable in almost all sediment and biota samples. Tributyltin concentrations in surface sediment ranged<2∼33 ng g$\^$-1/, which is at a lower end of TBT concentrations in industrialized bays in Korea. However, TBT levels in sediments were related to boating activities around the bay. In biota samples, TBT concentrations were in the range of 178∼2,458 ng g$\^$-1/ toy oyster and 47∼236 ng g$\^$-1/ for rock shell. Relatively high TBT concentrations in biota were found near wharves for fisherboats and harbor areas. About 90∼100％ of the female T. clavigera displayed imposex, and relative penis length index of the imposexed-female was in the range of 20.9∼107.9％. Furthermore, TBT body residue had a significant positive relationship with degree of imposex in T. clavigera. Overall, TBT concentrations in Gwanyang Bay were much lower than other major bays in Korea.