• Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.203-207
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• 2012

The amount of fluoride removed from Antarctic krill via organic acid extraction depends on the extraction time, concentration, extraction volume, and the nature of the acid itself. The fluoride content in Euphausia superba was determined by measuring the concentration of fluoride ion in acidic extracts using an ion-selective electrode. The best results were obtained by adding 50 mL of 0.01 M citric acid to 0.3-0.5 g of krill and extracting for 5 min. Under these conditions, recoveries of fluoride from frozen whole krill and krill meat were 95.6-99.5% and 97.5-101.3%, respectively. The dry basis fluoride contents of krill by-product, krill meat and the boiled krill were 705, 298, and 575 ppm, respectively. These levels were significantly reduced by citric acid extraction.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.5
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• pp.282-287
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• 2007

Chloroanilines are aromatic amines used as intermediate products in the synthesis of herbicides, azo-dyes, and pharmaceuticals. 3,4-dichloroaniline (DCA) is the degradation product of some herbicides (diuron, propanil, and linuron) and of trichlorocarbanilide, a chemical used as an active agent in the cosmetic industry. The compound, however, is considered a potential pollutant due to its toxicity and recalcitrant property to humans and other species. With the increasing necessity for bioremediation, we sought to isolate bacteria that degraded 3,4-DCA. A bacterium capable of growth on 3,4-DCA as the sole carbon source was isolated from seaside sediment using a dilution method with a culture enriched in 3,4-DCA. The isolated strain, YM-7 was identified to be Pseudomonas sp. The isolated strain was also able to degrade other chloroaniline compounds. The isolated strain showed a high level of catechol 2,3-dioxygenase activity on exposure to 3,4-DCA, suggesting that this enzyme is an important factor in 3,4-DCA degradation. The activity toward 4-methylcatechol was 53.1% that of catechol, while the activity toward 3-methylcatechol, 4-chlorocatechol and 4,5-chlorocatechol was 18.1, 33.1, and 6.9%, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.4
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• pp.458-465
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• 1999

Distribution of the proteolytic activities of crude pretense extracted from the viscera of ten kinds of fish was examined. Their proteolytic activities on proteinous substrates (azocasein, hemoglobin, and casein) from the viscera of anchovy, bastard flatfish, mackerel and red sea bream were higher than those of other fishes, and the crude pretenses were further fractoinated with acetone or ammonium sulfate. Optimum concentrations for pretenses fractionation were $0\~55\%$ for acetone and $30\~70\%$ for ammonium sulfate. The fractionated viscera pretense of mackerel showed the highest proteolytic activity among four kinds of fishes. Activities of cathepsin D- and pepsin-like enzymes at pH 3.0, cathepsin L-, B-, H- and G-like enzyme at pH 6,0, and Hypsin- and chymotrypsin- like enzymes (pH 8.0) were detected in the fractionated viscera pretense, whereas activities of cathepsin L- and chymoeypsin-like enzyme were observed in commercial pretenses. Proteolytic activities of Alcalase, Protamex, and Aroase AP-10 for azocasein were slightly higher than the fractionated viscera pretenses, but their amidolytic activities at pH 6.0 and 8.0 toward synthetic substrates were lower than counterpart. The fractionated pretenses from fish viscera would be utilized as commercial pretenses.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.2
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• pp.180-184
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• 2019

Aerobic bacteria, coliforms, Escherichia coli, and pathogenic bacteria were investigated in laver Porphyra sp. samples from various regions of Korea. The mean bacterial counts were $6.9{\pm}0.87log\;CFU/g$ (range 4.0 to 7.7) log CFU/g in dried laver, $2.83{\pm}4.36log\;CFU/g$ in roasted laver, and $4.93{\pm}1.43log\;CFU/g$ in seasoned laver. Coliforms were most abundant (mean count: $2.1{\pm}1.01log\;CFU/g$) in dried laver. No pathogenic bacteria, including Staphylococcus aureus, Salmonella spp. Vibrio parahaemolyticus, or Listeria monocytogenes, were detected in any of the samples. Aerobic microorganisms were the most diverse microorganisms in dried laver. Staphylococcus spp. were predominant, but S. aureus was not detected. Standardization of laver production is necessary to ensure a hygienic product because laver products are often ingested without heating or cooking, and the production process is simple.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.1
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• pp.74-80
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• 2019

Nonylphenol is an endocrine-disrupting chemical that is the degradation product of the nonionic surfactants nonylphenol ethoxylates. To understand the contamination and behavioral characteristics of nonylphenol, we measured the nonylphenol concentrations in surface water in the lower reaches of the Suyeong River, Korea. The results were used to estimate the material balance. The target area was divided into three regions to estimate the material balance of nonylphenol. In region 1, in flux of the dissolved nonylphenol was 282.3 g/day and the nonylphenol influx in particulate suspended solids was 1,582.8 g/day. The dissolved nonylphenol outflow discharged toward region 2 was 192.5 g/day, while the adsorption to particulate suspended solids was 89.8 g/day. Within the particulate suspended solids, the outflow to region 2 was 1,250.0 g/day, while the estimated amount settling in the sediments was 422.7 g/day. The adsorption of dissolved nonylphenol to the particulate suspended solids in regions 1 and 2 was 31.8% and 54.9%, respectively. In region 3, the desorption rate was 8.8%.

• Fisheries and Aquatic Sciences
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• v.25 no.2
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• pp.90-100
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• 2022

Cardiovascular diseases (CVDs) have posed serious public health problems, accounting for nearly 30% of mortality worldwide and their incidence is still increasing. Therefore, new treatment resources are necessary to prevent or manage the ever-increasing population of patients with CVDs. Sea cucumber is well known for its medical and health benefit effects, but it is not well known what/how effect it has on vascular disease. In the present study, we examined the protect effect of sea cucumber, Apostichopus japonicus 80% ethanol extract (AJE) on zebrafish embryo with the stimulation of free fatty acid, palmitate (PA). In vivo study showed that AJE can attenuate PA-induced toxicity through relieving the rapid heartbeat, increasing the survival rate and reducing the malformation in both wild type and Tg (fli1a:eGFP) transgenic zebrafish lines. Additionally, compare with PA treated embryos, the yolk sac area, body length, axial vascular segment (AVS) and intersegmental vessel (ISV) of the co-treatment group of AJE and PA were comparable to the control group. Moreover, AJE lowered the expression of inducible nitric oxide synthase (iNOS), nitric oxide (NO) and inflammation-related genes induced by PA, and inhibited PA-induced vascular development disorders. Our data preliminarily verify that AJE could be a candidate resource for the prevention or therapy of CVDs.

• Fisheries and Aquatic Sciences
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• v.26 no.6
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• pp.393-405
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• 2023

The aim of this research was to enhance the flavor of visceral extracts from skipjack tuna. Flavor precursors and the optimum condition for the Maillard reaction were determined. The flavor extract was prepared from the tuna viscera using Endo/Exo Protease controlled in 3 factors; temperature, enzyme amounts and incubation time. The optimal condition for producing tuna viscera protein hydrolysate (TVPH) was 60℃, 0.5% enzyme (w/w) and 4-hour incubation time. TVPH were further processed to tuna viscera flavor enhancer (TVFE) with Maillard reaction. The Maillard reactions of TVFE were conducted with or without supplements such as xylose, yeast extract and methionine. The Maillard volatile components were analyzed with gas chromatography-mass spectrometry. Sixteen volatiles such as 2-methylpropanal, methylpyrazine, 2,5-dimethylpyrazine, dimethyl disulfide and 2-acetylthaizone were newly formed via Maillard reaction and the similarity of volatile contents from TVPH and TVFE were virtualized using Pearson's correlation integrated with heat-map and principal component analysis. To virtualize aromagram of TVPH and TVFE, odor activity value and odor impact spectrum (OIS) techniques were applied. According to OIS results, 3-methylbutanal, 2-methylbutanal, 1-octen-3-ol 2,5-dimethylpyrazine, methional and dimethyl trisulfide were the potent odorants contributed to the meaty, creamy, and toasted aroma in TVFE.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.721-727
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• 2023

This study was conducted to evaluate the level of microbial contamination in smoked salmon products sold in hypermarkets in major metropolitan cities in Korea. Listeria monocytogenes is the primary cause of smoked and raw salmon product recalls. Here, we used L. monocytogenes as a bacterial hygiene indicator and investigated the microbial contamination level of frozen/refrigerated smoked salmon products collected from hyper markets. Contamination levels were analyzed by seasons, manufacturers, and consumption regions. For hygiene indicator bacteria, total bacteria count, coliforms, and Escherichia coli were examined according to the food code established by the Ministry of Food and Drug Safety, and polymerase chain reaction (PCR) was performed to detect Listeria sp. The highest contamination level was observed in spring in Busan among five consumption regions. Listeria was detected at a level of 2.1% among all samples collected. And especially L. monocytogenes was detected in two cases from the samples collected from Daegu and Daejeon. Sanitary standards and specifications should be established according to the contamination level of smoked salmon products investigated in this study, and continuous monitoring is necessary.

• Fisheries and Aquatic Sciences
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• v.26 no.11
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• pp.678-688
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• 2023

Flatfish are one of the largest families in the order Pleuronectiformes and are economically important edible marine fish species. However, they have similar morphological characteristics leading to challenges in classifying correctly, which may result in mislabeling and illegal sales, such as fraudulent labeling of processed food. Therefore, accurate identification is important to ensure the quality and safety of domestic markets in Korea. Species-specific primers were prepared from the mainly consumed eleven species of the order Pleuronectiformes. To rapidly identify the 11 flatfish species, a highly efficient, rapid, multiplex polymerase chain reaction (PCR) with species-specific primers was developed. Species-specific primer sets were designed for the mitochondrial DNA cytochrome c oxidase subunit I gene. Species-specific multiplex PCR (MSS-PCR) either specifically amplified a PCR product of a unique size or failed. This MSS-PCR analysis is easy to perform and yields reliable results in less time than the previous Sanger sequencing methods. This technique could be a powerful tool for the identification of the 11 species b the family Pleuronectidae and can contribute to the prevention of falsified labeling and protection of consumer rights.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.6
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• pp.839-846
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• 1994

Changing concepts in fishery science increasingly are recognizing depletion of traditional stocks, utilization of alternate(non-traditional) species, demand for high quality products, and a total resource utilization approach. Innovative practices are occurring in fisheries processing wherein solid and liquid discharges are no longer treated as 'waste,' but rather as valuable feedstocks for recovery of a variety of value-added ('value enhanced') by-products. Among these are protein hydrolysates, soluble proteins and amino acids, proteolytic enzymes, flavor and flavor extracts, pigments, and biopolymers such as chitosan. Properties and applications of this deacetylated derivative of chitin are noted. Crustacean processing by-products are discussed in terms of their serving as materials for generation of natural flavors and flavor extracts, and products such as fish sauces using contemporary enzymatic techniques. Various food and feed applications of fisheries processing by-products are illustrated with increased usage seen in formulated diets for an expanding aquaculture market. Examples are given of aquaculture becoming increasingly significant in global fisheries resource projections. Critical issues in the international seafood industry Include those of seafood quality, processing quality assurance (HACCP), and recognition of the nutritional and health-related properties of fisheries products. A variety of current seafood processing research is discussed, including that of alternate fish species for surimi manufacture and formulation of value-added seafood products from crawfish and blue crab processing operations. Increasing emphasis is being placed on international aspects of global fisheries and the role of aquaculture in such considerations. Coupled with the need for the aquatic food industry to develop innovative seafood products for the 21st century is that of total resource utilization. Contemporary approaches in seafood processing recognize the need to discard the traditional concept of processing 'waste' and adapt a more realistic, and economically sound, approach of usable by-products for food and feed application. For example, in a period of declining natural fishery resources it is no longer feasible to discard fish frames following fillet removal when a significant amount of residual valuable flesh is present that can be readily recovered and properly utilized in a variety of mince-based formulated seafood products.