• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.12
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• pp.1596-1603
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• 2007

This study was conducted to improve functional properties of salmon frame extracts using various commercial enzymes (Alkalase 2.4 L FG, Flavourzyme 500 MG, Neutrase 0.8 L and Protamex 1.5 MG). The ACE (angiotensin I converting enzyme) inhibitory activity was the highest ($IC_{50}=0.67mg/mL$) in the product incubated with Neutrase for 4 hrs (N4-treated hydrolysates) among the various extracts incubated with commercial enzymes for different times. However, antioxidant activities of all salmon frame extracts were less than 15%. There were no significant differences in the proximate composition and sensory evaluation of the fish odor and taste. However, N4-treated hydrolysate was improved in the extractive-nitrogen content and transmission compared to the other enzymatic hydrolysates. When compared to commercial Gomtang products, N4-treated hydrolysate was also high in protein, extractive-nitrogen, total amino acid, and calcium contents, while low in taste sensory score. There were no differences in transmission and sensory score on the fish odor between N4-treated hydrolysates and commercial Gomtang.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.1
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• pp.18-24
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• 2011

This study investigated the physicochemical and enzymatic properties of unmarketable cultured bastard halibut (Paralichthys olivaceus) of different weights as a potential source of surimi and surimi gel. The proximate composition of cultured bastard halibut of different weights did not differ significantly at P<0.05 (light weight (LBH) 400~500 g, medium weight (MBH) 600~800 g, and heavy weight (HBH) > 1,000 g). Compared to Alaska pollock muscle, the bastard halibut muscle had a 4% higher crude protein content and 6% lower moisture content. The collagen content of LBH bastard halibut muscle was 1.58 g/100 g, which was lower than or no different from bastard halibut weighing different amounts. Regardless of fish weight or pH, the enzymatic activities of crude fish extracts ranged from 0.34~0.48 U/mg for casein and hemoglobin, 11.0~12.7 U/mg for LeuPNA, 5.4~6.1 U/mg for ArgPNA, 2.3~2.9 U/mg for SAAPFNA, and 0.1~0.2 U/mg for BAPNA. The yield of surimi gel from LBH was 24.4%, which was similar to that from MBH and lower than that from HBH. The surimi gel from LBH was similar to that from HBH, while weaker than that from MBH. The surimi gel from LBH gel was stronger than grade SA gel from commercial Alaska pollock.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.6
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• pp.762-771
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• 2010

Two experiments were conducted to determine i) the fermentation characteristics of catfish by-product (C) ensiled with rice bran (RB) or sugarcane molasses (M) in different ratios, and ii) the digestibility of the silages in growing pigs. In the ensiling experiment, there were three ratios of C, ensiled with RB or M, of 8:2, 7:3 and 6:4 (wet basis for C and air-dry basis for RB and M). The six treatments were CRB8:2, CRB7:3, CRB6:4, CM8:2, CM7:3 and CM6:4, with 3 replications per treatment and seven sampling times. The pH of CRB7:3 and CRB6:4 decreased (p<0.05) from the first week and stayed stable until 8 weeks of ensiling, but the pH did not decrease in CRB8:2. The pH of CM8:2, CM7:3 and CM6:4 decreased rapidly from the first week until week 8. Dry matter (DM) and crude protein (CP) contents were slightly lower when catfish by-product was ensiled with RB than with M. Ammonia content in all treatments increased (p<0.05) during ensiling. Lactic acid content in silages with molasses increased from the first week, with the highest value at week 4. However, the lactic acid content in CRB8:2 did not increase with time and had the lowest value of all treatments. Acetic acid proportions of total volatile fatty acids were low at day 0, with the highest value at day 7, decreasing slowly until 8 weeks. The butyric acid proportion was highest at day 0 and decreased up to week 8. The proportion of propionic acid increased during ensiling. The digestibility experiment had a 4${\times}$4 Latin-square design and included 4 castrated crossbreed (Yorkshire${\times}$Landrace) male pigs fed four diets. The basal diet (BD) included rice bran, broken rice and maize meal, and the other three diets included fish meal (FMD) or catfish by-product ensiled with rice bran (CRBD) or sugarcane molasses (CMD). The silages chosen were those which gave the best results in the ensiling experiment for each additive. The coefficient of total tract apparent digestibility (CTTAD) of DM and organic matter (OM) was not significantly different among treatments. The CTTAD of CP was not different among the silage diets, but was lower in BD (p<0.01). The CTTAD of ether extract (EE) was higher in the catfish by-product silage diets than in FMD and BD. There was no significant difference in the digestibility of DM, OM, CP and EE between the fish meal and the by-product silages. In conclusion, catfish by-product can be successfully preserved by ensiling. Moreover, the total tract apparent digestibility of OM, CP and EE in ensiled catfish by-product was comparable with that of fish meal.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.6
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• pp.612-618
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• 2012

The proximate and fatty acid compositions of the edible portion of three species of cultured freshwater fish (common eel Anguilla japonica, rainbow trout Onchorhynchus mykiss, and Israeli carp Cyprinus carpio) were compared between imports from China and domestically produced specimens. The lipid contents of cultured common eel and rainbow trout were rich in imported fishes (20.4 and 12.2%, respectively) compared with those in domestic ones (16.0 and 8.01%, respectively), while those of Israeli carp were rich only in the domestically produced specimens (8.06 and 3.07%, respectively). There was a negative correlation between the lipid and moisture contents in all fish samples (r =-0.86). The protein contents ranged from 16.6 to 21.3% in domestic fishes and 15.3 to 19.1% in imported ones. The most prominent fatty acids in the fishes were: saturated fatty acids, 16:0, 18:0 and 14:0; monounsaturated fatty acids, 18:1n-9, 16:1n-7 and 18:1n-7; and polyunsaturated fatty acids (PUFA), 18:2n-6, 22:6n-3 (docosahexaenoic acid, DHA), and 20:5n-3 (eicosapentaenoic acid, EPA). The percentage of n-3 PUFA (e.g., DHA, 22:5n-3, EPA, and 18:3n-3) was higher in domestic common eel and Israeli carp than in imported ones, but similar in domestic and imported rainbow trout, and higher in domestic wild rainbow trout than in cultured ones. On the other hand, all of the cultured freshwater fishes contained a relatively large amount of 18:2n-6, which is a characteristic fatty acid in cultured fish lipids.

• Journal of fish pathology
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• v.8 no.2
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• pp.111-118
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• 1995

This experiment was carried out in order to elucidate the effect of NaCl(0.85%) acclimation on congestion symptoms in central venous sinuses(CVS) of gill filaments and on the alteration of blood constituents in cultured eels for 1, 2, 3, 4, 5, 6 and 7days after handling stress. After giving a handling stress on eels, the frequency of gill congestion was about 90%. It gradually decreased to 40% on the 3rd day, then increased to 60% on the 7th day in NaCl(0.85%) acclimation. The values of haematocrit(Ht), methemoglobin(Met-Hb), glucose (GLU), calcium($Ca^{++}$), lactic dehydrogenase(LDH), glutamic pyruvic transaminase (GPT) and glutamic oxaloacetic transaminase(GOT) were lower than those of the control, whereas magnesium($Mg^{++}$) and haemoglobin(Hb) were higher than the control. However total protein(Tp) and albumin (ALB) levels similar to the control. When the fish after giving a handling stress were cultured in NaCl-free water as a control, the frequency of gill congestion and the value of blood components showed a similar pattern to that obtained from the NaCl acclimated experiments. However, in the early period(1-3day) after handling stress, NaCl acclimating slightly helped the natural tendancy of recovery. These results suggest that the frequency of gill congestion is not always reduced over the whole period of NaCl acclimation. However, the acclimation to NaCl solution may be a somewhat useful therapy for the gill congestion in stressed eels.

• Journal of fish pathology
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• v.22 no.3
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• pp.375-382
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• 2009

Integration and expression of a target gene into chromosomal genomes of host cell by retrovirus mediated gene transfer system usually require complicate and laborious procedures. In the present study, we investigate a simple method to integrate a target gene into genome of BF-2 cells using ultraviolet (UV)-inactivated snakehead retrovirus (SnRV), a fish retrovirus. First of all, an optimization of transfection condition was determined with BF-2 cells using Lipofectamine 2000 and Transome. Using 0.5 $\mu\ell$ Lipofectamine 2000 resulted in 33.8, 40.6 and 40.2% of transfection efficacy with high survival rate (minimum 80%) in 0.5, 1 and 2 $\mu{g}$ DNA, respectively, and those of Transome were all less than 5%. It was confirmed that UV-treatment for 5 min was enough to inactivate infectivity of SnRV. Next, a cassette composed of GFP (green fluorescent protein) gene flanked by LTR (long terminal repeats) sequences derived from SnRV was constructed and transfected into BF-2 cells followed by treatment with UV-inactivated SnRV for optimization of integration and expression of the cassette gene. As the results, the fluorescence was expressed in BF-2 cells treated with UV-inactivated SnRV 3 and 5 times, while there was no expression in BF-2 cells with once and non treatment. Accordingly, it was confirmed that GFP gene was integrated into chromosomal genome of BF-2 cells with UV-inactivated SnRV.

• Journal of fish pathology
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• v.11 no.1
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• pp.43-50
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• 1998

In order to determine whether the tumor-inducing iridoviruses and the mortality-associated iridoviruses from cultured marine fish in Korea belong to same type, we compared the immunological characteristics of these viruses. The electrophoretical pattern of structural proteins of the tumor-inducing was different from that of the mortality-associated iridoviruses. The antigenicity of structural proteins of these viruses were identified by Western blotting using two monoclonal antibodies against tumor-inducing iridovirus. Two monoclonal antibodies recognized a 150 kDa structural protein of tumor-inducing iridoviruses showed. However, the structural proteins of the mortality-associated iridoviruses did not react with these monoclonal antibodies. These results demonstrate that the antigenicity of the structural proteins of tumor-inducing iridovirus is different from that of mortality-associated iridovirus, indicating that these two iridoviruses belong to different types.

• Korean Journal of Food Science and Technology
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• v.43 no.3
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• pp.282-290
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• 2011

Two species of demersal fish, Liparis tessellates (cubed snailfish) and Hemitripterus villosus (shaggy sea raven), were investigated in relation to seasonal chemical composition. Total fat contents of the two fish were very low and were not appreciably different throughout the year, whereas their fatty acid compositions were significantly different depending on season. Noticeable changes in the moisture and protein contents in the two fishes were observed before and after spawning. Cubed snailfish showed relatively high amounts of total amino acids and free amino acids during summer months, whereas the levels of those in shaggy sea raven remained relatively unchanged throughout the year. Regardless of season, the major fatty acid of the two fishes was palmitic acid and most of polyunsaturated fatty acids (PUFAs) were n-3 PUFAs. Lead was over the legislative limit in some samples of the two fishes.

• The Korean Journal of Food And Nutrition
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• v.21 no.2
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• pp.165-175
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• 2008

Pacific saury, Cololabis saira kwamaegi, is a traditional local food of the Eastern sea area centering around Pohang. It is well-recognized as being both tasty and nutritious. Nevertheless, bacterial contamination, excessive dryness, and compositional changes have made it edible only during the winter months. Therefore, to improve its storage, this study examined the effects of storage material, type, temperature, and duration on compositional changes in kwamaegi. The studied samples were kwamaegis that had been dried naturally for 15 days. The storage materials included an A-film, a self-developed multi-film made of polyethylene, polyamide, EVOH, and polyethylene; as well as a B-film made of polyethylene, nylon, polyethylene, nylon and polyethylene. The B films were used after pressing and laminating. The storage types included one whole fish(1G), or 2 divided fish(2G), to increase eating convenience. The 2G type was the muscle portion divided vertically after discarding the jowl, skin, and internal organs. The storage temperatures were $0^{\circ}C$, $-15^{\circ}C$, and $-30^{\circ}C$, and the storage durations were 2, 4, and 6 months. Pathogenic bacteria and rheology were measured to observe general compositional changes. The whole kwamaegi showed a total cell number of $1,565{\pm}112$ CFU/100 g flesh, while the divided Kwamaegi showed significantly greater bacterial numbers at $2,031{\pm}145$ CFU/100 g flesh. Psychrophils and halophils increased significantly while coliform were not found; the number of mesophils also increased, but not significantly. There were no significant cell number variations between the A-film and B-film. At $0^{\circ}C$, both the A-and B-films resulted in cell numbers of $115{\sim}212$ CFU/100 g flesh, revealing just $7.3{\sim}10.4%$ of the initial storage levels. Overall, there were no significant differences between the storage materials. Generally, as the storage temperature and duration increased, the moisture content of the kwamaegi decreased. Also, as storage duration and temperature increased, crude protein and crude lipid contents increased; in addition, they increased proportionally as the moisture content of the fish decreased. There were no significant differences in crude ash content with respect to the storage materials, storage temperatures, or storage durations. Finally, there were no significant differences between the kwamaegi samples naturally dried for 15 days and those stored in the B-film vacuum storage for 6 months for strength, hardness, cohesiveness, springiness, gumminess, and water activity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.588-593
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• 2001

Rockfish (Sebastes schlegeli) juveniles were fed with the diets containing 0 (control and sham), 5, 10 and 15 ppm of 3,5,3'-triiodo-L-thyronine ($T_3$) for 50 days to assess the effect of the hormone on the change of physiological condition, growth and survival rate, fish were fed the commercial diet by hand to satiation 2 times per day. After 50 days, food intake, feed efficiency, thyroid cell height (TCH), abnormality, proximate body composition, growth, condition factor and survival rate were also examined. The food intake and the feed efficiency of S. schlegeli fed with diet containing 10 ppm of $T_3$ was significantly higher than those of fishes fed with the other diets. On the final day of experiment, atrophy of thyroid gland was observed in fish administered with 10 and 15 ppm of $T_3$. $T_3$increased slightly the abnormality according to the increase of $T_3$dose. The whole body proximate analyses indicated that the fishes administrated with 15 ppm of $T_3$ were the highest in protein content and were the lowest in lipid, but in ash content were there a significant effects of $T_3$. The growth of S. schlegeli fed with a diet containing 10 ppm of $T_3$ was significantly higher than that of control. The condition factor was not related to administered $T_3$ content. $T_3$ slightly improved the survival rate of juvenile S. schlegeli, and the survival rate of fish administered with 10 ppm was significantly higher than that of sham-control but was lower than that of control.