• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.49 no.3
• /
• pp.270-276
• /
• 2016

This study investigated the sensory characteristics (texture, odor, taste and color) of jerky produced from ground sea rainbow trout (SRT) Oncorhynchus mykiss frame muscle (FM). The hardness of the ground SRT-FM jerky was 453.9±91.0 g/cm², which was lower than that of commercial animal jerky (893.5±404.6 g/cm²) and commercial fish jerky (1,394.4±363.5 g/cm²). The difference in the hardness values of the ground SRT-FM jerky and commercial animal jerky was not significant. The volatile basic nitrogen content of the ground SRT-FM jerky was 48.3±1.6 mg/100 g, which was higher than that of commercial fish jerky (21.6±6.2 mg/100 g) and commercial animal jerky (18.2±6.3 mg/100 g). However, the fish odor of the ground SRT-FM jerky was masked by the presence of various additives. The hydrophilic and lipophilic browning indices of the ground SRT-FM jerky were higher than those of the commercial jerky. The total taste value of the ground SRT-FM jerky was 169.0, and the major amino acids were glutamic acid and aspartic acid. These results suggest that ground SRT-FM jerky would be acceptable to consumers.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.49 no.3
• /
• pp.263-269
• /
• 2016

Large quantities of by-products—such as fish frame, head, skin and viscera—are generated during seafood processing, and these by-products are not utilized extensively. Therefore, sea rainbow trout Oncorhynchus mykiss (SRT) frame muscle (FM) jerky was prepared by grinding SRT-FM, followed by mixing with seasoning, forming and drying. The nutritional and microbiological characteristics of the SRT-FM jerky were then investigated. The proximate composition of the SRT-FM jerky was 19.1% moisture, 38.7% crude protein, 7.9% crude lipid and 4.4% ash. The viable bacterium count of the SRT-FM jerky was 3.9 log CFU/g, and Escherichia coli and Staphylococcus aureus were not detected. The total amino acid content of SRT-FM jerky was 37.3 g/100 g, and the major amino acids were aspartic acid, glutamic acid, leucine and lysine. Based on the recommended daily intake of fish jerky (100 g), the most abundant mineral was potassium. The fatty acid composition of the SRT-FM jerky was 26.2% saturated acid, 34.5% monoenoic acid and 39.3% polyenoic acid, and the major fatty acids were 16:0, 18:1n-9, 18:2n-6, 20:5n-3 and 22:6n-3. These results suggest that SRT-FM jerky has high nutritional value.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.44 no.3
• /
• pp.225-231
• /
• 2011

Prolactin (PRL) plays an important role in freshwater (FW) osmoregulation by preventing the loss of ions and the uptake of water in fish. Growth hormone (GH) promotes acclimation to seawater (SW) in several teleosts. We acclimated rainbow trout Oncorhynchus mykiss weighting $68.2{\pm}16.6$, $138.3{\pm}24$, and $287.5{\pm}42.1$ g in separate experiments to SW under slow-acclimation (SSW) or acute-acclimation (ASW) conditions, and then examined the PRL and GH mRNA levels using the real-time quantitative polymerase chain reaction. The PRL mRNA levels in all three experimental groups decreased significantly with both the SSW and ASW treatments, as compared to a control group kept in FW for 30 days. The GH mRNA levels increased with ASW in the largest fish, whereas the levels in the other groups did not change significantly. The mortality rate of the largest fish was lower than for the other groups, whereas the growth rate among the three experimental groups did not differ significantly. The growth rate of the ASW group was highest for the smallest fish. These results suggest that SW acclimation is associated with the gene expression levels of PRL and GH in relatively large rainbow trout. In addition, the fish mortality and growth rate on FW-SW transfer seem to be related to body weight, and the SW acclimation method may be applied to the hatcheries industry.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.47 no.2
• /
• pp.103-113
• /
• 2014

This study compared the food quality of freshwater rainbow trout Oncorhynchus mykiss cultured (in Pyeongchang, Pyeongtaek, Jecheon and Geochang) with that of imported salmon Oncorhynchus keta. The proximate composition of the four types of rainbow trout was 74.4-75.7% moisture, 18.3-19.4% crude protein, 3.1-4.3% crude lipid, and 1.3-1.7% ash. There were slight differences in the proximate composition of the four types of rainbow trout. No significant (P>0.05) differences were found in the red color and odor and taste intensities of the four types of rainbow trout based on the Hunter a values, volatile basic nitrogen content, odor intensity using an electronic nose and taste intensity using an electronic tongue. The crude protein, total amino acid, and mineral contents of rainbow trout cultured in Pyeongtaek were superior or similar to those of the trout cultured in the other three places. The rainbow trout cultured in Geochang had the highest hardness, at 858.5 g.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.51 no.3
• /
• pp.254-261
• /
• 2018

From 2014 to 2017, mortalities of seawater-cultured rainbow trout Oncorhynchus mykiss, were observed in the Goheung and Jeju areas of Korea, with Vibrio anguillarum (seven strains: RT1, 2, 3, 4, 5, 6, and 7) identified as the etiological agent. The phenotypic (based on API 20NE, API ZYM, and E-test kits), serotypic (slide agglutination tests with O1, O2, O3, O4, and O7 antisera), and genotypic (16S rRNA and ompU sequencing) characteristics of the seven RT strains were analyzed and compared to those of seven additional V. anguillarum stains (SF, isolated from sweet fish; FM, isolated from flathead mullet; ATCC43305; ATCC43311; ATCC43307; ATCC43308; and KCTC2711). The phenotypes of the RT strains showed variance, while the slide agglutination tests of the RT1-7, SF, and FM strains all showed positive reactions with serotype O1 antiserum. The 16S rRNA and ompU sequences of the RT1-7, SF, and FM strains were affiliated with V. anguillarum ATCC43305 (Serotype O1), but the ompU sequence of the SF strain differed from those of the RT1-7, FM, and ATCC43311 strains, including one amino acid substitution. We thus confirmed that serotype O1 V. anguillarum, with multiple phenotypes, continues to infect seawater-cultured rainbow trout in Korea.

• Korean Journal of Microbiology
• /
• v.35 no.3
• /
• pp.226-230
• /
• 1999

To characterize the Korean isolate of infeciious hematopoietic necrosis virus (IHNV-PRT), a partial DNA fragment G gene of the MNV-PRT was amplified by RT-PCR. cloned inlo pGEM-T easy vector and analyzed for nucleotlde sequences. The size of the PCR pmduct was about 442 bp. The nucleotlde sequence homologies ofthe G gene of IHNV-PRT were 95%, 94%, 94% 94%, 93%, 53%. respectively. with those of foreign isolates of IHNV, IHNV-RB-76. IHNV-LR-73, MNV-K, IHNV-WRAC, Im-SRCV, IHNV-Col-85. However, it showed 81% homology with that of other fish rhabdovirus, hisame rhabdovirus (HRV). Frou~ the rcsults of deduced amino acid sequence homology analysis. G protein of IHNV-PRT showed 96% hornologies with those of foreign isolates of IHNV but 89% homology with that of HRV These results indicaled that, even though G gene of IHIW-PRT showed low homology with that of HRY it was highly conserved among different strains of THNV.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.48 no.1
• /
• pp.26-35
• /
• 2015

This study compared the meat quality of sea rainbow trout Oncorhynchus mykiss frame muscle (S-FR-TY) and fillet (S-FI-TY) with the frame muscle of freshwater rainbow trout (F-FR). There was a difference of < 1% in the proximate composition of S-FR-TY vs. S-FI-TY, and of S-FR-TY vs. F-FR. The Hunter a value of F-FR-TY was lower compared with that of F-FR cultured in Jecheon (F-FR-JC), but higher than that of F-FR cultured in Pyeongtaek (F-FR-PT). However, no difference in the Hunter a value of S-FR-TY compared with any other F-FR was observed. The odor intensity of S-FR-TY was lower compared with that of F-FR, while the taste of S-FR-TY was milder than that of S-FI-TY, but stronger than that of F-FR. Although its total amino acid content was lower, the essential amino acid content of S-FR-TY was higher compared with S-FI-TY; the potassium content of S-FR-TY was also significantly greater. S-FR-TY contained high levels of nutritional and functional components, such as anserine, lysine, threonine, and eicosapentaenoic and docosahexaenoic acid. These results suggest that S-FR-TY could be used as a resource of canned food or fish jerky for children.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.47 no.6
• /
• pp.832-839
• /
• 2014

To evaluate the digestive characteristics and bioavailability of dietary soybean meal (SBM), the post-prandial changes in the gastric contents of rainbow trout Oncorhynchus mykiss were determined for 24 h after feeding of SBM diets. A curve estimation of regression diagnostics using a comparison of the adjusted $r^2$ and probability was performed to test the tendency of the post-prandial changes and gave a quadratic polynomial (exponential) regression for all experimental groups. The gastric evacuations rates (GER) for higher-SBM groups were slower than those for lower-SBM groups. The estimated GER (digestion time) for 75% gastric content for fish fed a 70% SBM diet was 1.63 times longer than that for fish fed the control diet. Despite the fact that the pH values in the gastric contents rose from 4.05 at 0 h to 5.12-5.38 at 1 h after feeding, then dropped to 4.57-4.83 at 9 h, with no significant differences among experimental groups, the gastric moisture contents increased significantly in the higher-SBM groups. This is most likely due to an increase in digestive juices in the higher-SBM groups, rather than water introduced externally. The percentage of soluble nitrogen in the gastric contents of fish fed the higher-SBM diets was higher than that in the fish fed the control diet, and the SBRs (stomach weight/body weight${\times}100$) in the higher-SBM groups (diets 4, 5, 6 and 7) were also significantly higher than the SBR of the control group (P<0.05). This may indicate that the protein in SBM can be digested slowly due to physiological digestive adaptation in rainbow trout.

• Journal of Aquaculture
• /
• v.18 no.2
• /
• pp.69-75
• /
• 2005

One 30-day feeding trial was conducted to examine the effects of dietary salt on seawater adaptability of rainbow trout (Onchorhynchus mykiss) fed three experimental diets containing 0% (control), 4% and 8% salt. The experimetal period included 30 days of feeding trial in freshwater, 3 days of the step by step seawater acclimation with-out feeding diets, and 21 more days of seawater adaptation period (not with all experimental fish) with feeding the basal diet. Growth rates from triplicate groups were determined fur 30 days of feeding trial. Blood samples were taken at the begining and at the end of feeding trial, and 3 times (on 1st, 4th and 8th day) of the seawater adaptation period. Daily survival rates of duplicate groups from three experimetal treatments were recorded for 21 days of the seawater adaptation period. Total average initial and final fish weight were $149.5{\pm}7.6\;and\;187.1{\pm}7.6g$. Feed efficiency of fish fed diets containing 4% and 8% salt were significantly better than those of fish fed the control diet. Average cumulative survival rates were 72, 80 and 88% from the control, 4% and 8% salt diets, respectively. Pulse rate per minutes decreased with dietary salt level. Serum $Na^+\;and\;Cl^-$ concentrations of fish fed 4% and 8% salt diets were significantly higher than those of fish fed the control diet (P<0.05), however, the concentrations were stabilized after 8 days of seawater adaptation. Serum cortisol, glucose, cholesterol and tryglyceride concentrations, and the osmorality of fish decreased with dietary salt level, these values were significantly lower than those of fish fed the control diet. These results indicated that the dietary supplementation of salt could have advantages for seawater adaptability of rainbow trout.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.55 no.5
• /
• pp.688-696
• /
• 2022

Obesity could cause immune-physiological disorders in fish. Yet, little is known about the impact of obesity on stress and histological responses. This study aimed to determine histological and physiological changes in and vulnerability of overfeeding-induced obese rainbow trout Oncorhynchus mykiss exposed to stress condition. Control, intermediate and overfed groups were fed at 1.5, 2.5 and 3.09% of their body weight per day, respectively, for eight weeks. Weight gain, body mass index, hepatosomatic index and serological parameters, and histology of liver were measured in five fish from each group at week 0, 2, 4, and 8. At week 8, 20 fish from each group were exposed to heat stress by increasing water temperature at a rate of 3℃ per day from 15 to 25℃ and maintaining the final temperature for 10 days. Overall, overfed fish showed significantly higher weight gain, body mass index, and serological parameters than those of fish in the other groups. Fish in the overfed and intermediate groups displayed multifocal infiltration of inflammatory cells in hepatic parenchyma. Mortality rate and serological parameters of fish in the overfed group exposed to heat stress were significantly higher than those of fish in the other groups, indicating increased vulnerability to environmental stress.