• Fisheries and Aquatic Sciences
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• v.21 no.8
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• pp.29.1-29.8
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• 2018

This study was conducted to evaluate the use of tuna by-product meal (TBM) as a substitute for fishmeal in juvenile Korean rockfish (Sebastes schlegeli) diets. Five isonitrogenous (52% crude protein) and isocaloric (4.9 kcal/g) diets were prepared. Control diet (Con) was formulated to contain brown fishmeal, whereas 25, 50, 75, and 100% of fishmeal was substituted with the same percentage of TBM in the TBM25, TBM50, TBM75, and TBM100 diets, respectively. Three replicate groups of fish (initial weight, $29.5{\pm}0.6g$) were fed one of the five diets for 12 weeks. The mean weight gain of fish fed the Con and TBM25 diets was significantly higher than that of fish fed the TBM100 diet (P < 0.05), but it was not significantly different from the weight gain of fish fed the TBM50 and TBM75 diets. The feed efficiency and protein efficiency ratios of fish fed the Con diet were significantly higher than those of fish fed the TBM100 diet (P < 0.05), but were not significantly different from those fed the TBM25, TBM50, and TBM75 diets. The TBM25, TBM50, TBM75, and TBM100 diets had significantly (P < 0.05) lower incidence cost and higher profit index than the Con diet. These results suggest that the tuna by-product meal used in this study could replace up to 75% of fishmeal protein in the diet without reducing growth and feed utilization in juvenile Korean rockfish weighing 29-53 g. By considering feed cost, the TBM 75 diet is recommendable for Korean rockfish farming.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.73-73
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• 2003

This study was carried out to evaluate the utilization of fermented skipjack tuna viscera (FSTV) in the diet for juvenile abalone Haliotis discus hannai. Lactobacillus bulgaricus was used for fermentation of skipjack tuna viscera. Eight isonitrogenous (about 30% crude protein) diets were formulated to include different levels (0%, 10%, 20% and 30%) of FSTV as a replacer of either dietary fish meal or soybean meal. Three replicate groups of abalone were fed the experimental diets containing different levels of FSTV for 7 weeks. The inclusion of FSTV up to 30% in fish meal-based diet had no significant effect on survival, body weight, shell growth, and proximate composition of abalone (P>0.05). Weight gain of abalone fed the diet substituting 10% FSTV for soybean meal was not significantly different to that of abalone fed the control diet, however this value decreased in abalone fed the 20% and 30% FSTV (P<0.05).The contents of crude protein and lipid of soft body in abalone fed soybean meal-based diets were significantly affected by dietary FSTV level (P<0.05). The results of this study indicate that FSTV can be used as a partial substitute protein source for fish meal or soybean meal in the formulated diet for juvenile abalone.

• 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.741-748
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• 2023

This study evaluated the supplemental effects of linseed oil (LO) as a substitute for docosahexaenoic acid oil (DHAO) in the diet of juvenile Atlantic bluefin tuna. A control diet (DHA) was formulated to contain 65% enzyme-treated fish meal and 3% of DHAO. A LO diet was formulated to contain 1% LO replacing 1% DHAO in DHA diet. In a feeding trial, 300 juvenile bluefin tuna (initial body weight 1.15 g) were randomly divided into two concrete tanks (70 ton capacity) and fed one of the experimental diets for 13 days. Weight gain was higher in the LO group (519%) than in the control (443%) while survival and protein digestibility were similar between groups. The biological assessment of the tuna digestive organs did not differ between the DHA and LO groups. The fatty acid composition of the carcass showed that α-linolenic acid was only observed in the LO group, and there was no difference in the composition of eicosapentaenoic acid and docosapentaenoic acid between the groups. These results indicate that LO could be a dietary good oil source for Atlantic bluefin tuna without apparent negative effects.

• Food Science and Biotechnology
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• v.18 no.6
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• pp.1330-1335
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• 2009

Although beneficial effects of dietary plant proteins on lipid metabolism are well documented, not much information exists on the influence of different seafood proteins on the lipid metabolism. The present study evaluated the effect of 2 marine proteins (tuna protein and scallop ovary proteins) in comparison to casein and soy protein in male Wistar rats. The concentration of total lipids in the plasma of rats fed experimental diets was significantly lower from that of control (278.2 mg/dL) group (p<0.05); and, the liver lipid content was not significantly different (p>0.05). Fecal excretion of cholesterol and bile acids was significantly higher in marine proteins and soy protein fed groups compared to casein only fed control (6.1 and 6.4 mg/day, respectively) group (p<0.05). No significant differences were observed in the mRNA concentrations of different transcriptional factors (p>0.05).

• Fisheries and Aquatic Sciences
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• v.25 no.6
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• pp.335-349
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• 2022

To optimize the hydrolysis conditions in the production of antioxidant hydrolysates from tuna cooking juice concentrate (TC) to maximize the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, TC containing 48.91% protein was hydrolyzed with Alcalase 2.4 L, and response surface methodology (RSM) was applied. The optimum hydrolysis conditions included a 2.2% (w/v) Alcalase concentration and 281 min hydrolysis time, resulting in the highest DPPH radical scavenging activity of 66.49% (0.98 µmol Trolox/mg protein). The analysis of variance for RSM showed that hydrolysis time was an important factor that significantly affected the process (p < 0.05). The effects of different drying methods (freeze drying, hot air drying, and vacuum drying) on the DPPH radical scavenging activity and amino acid (AA) profiles of TC hydrolysate (TCH) were evaluated. Vacuum-dried TCH (VD) exhibited an increase in DPPH radical scavenging activity of 81.28% (1.20 µmol Trolox/mg protein). The VD samples were further fractionated by ultrafiltration. The AA profiles and antioxidant activities in terms of the DPPH radical scavenging activity, 2,2'-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging activity, ferric reducing antioxidant power, and ferrous ion chelating activity were investigated. Glutamic acid, glycine, arginine, and cysteine were the major AAs found in the TCH fractions. The highest DPPH radical scavenging activity was found in the VD-1 fraction (< 5 kDa). The VD-3 fraction (> 10 kDa) exhibited the highest ABTS radical scavenging activity and ferric reducing antioxidant power. The ferrous ion chelating activity was the highest in VD-1 and VD-2 (5 to 10 kDa). In conclusion, this study provided the optimal conditions to obtain high antioxidant activities through TCH production, and these conditions could provide a basis for the future application of TCH as a functional food ingredient.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.1
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• pp.38-42
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• 2000

Thig study was conducted to get a knowledge on chemical components of the cooked tuna bones (skipjack tuna bone and yellowfin tuna bone) as a food resource. The crude protein of tuna bone was around $29{\%}$ on the dry basis. The imino acid content (193 imino acid residues /1,000 amino acid residues) of collagen extracted from yellowfin tuna bone was higher than that (173 imino acid residues /1,000 amino acid residues) of collagen extracted from skipjack tuna bone, however, it was lower than that of collagen extracted from animal bone. The content and the ratio of unsatuated fatty acids in lipid extracted from yellowfin tuna bone were higher than those of lipid extracted from skipjack tuna bone, but they were lower than those of squid viscera oil. The contents of calcium and phosphorus as the major components of the tuna tone were 36.5 g and 17.2 g in 100 g ash in the skipjack, respectively, and 38.0 g and 18.7 g in 100 g ash in the yellowfin, respectively. It was concluded from these results that tuna bones could be effectively utilized as a mineral source.

• Fisheries and Aquatic Sciences
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• v.19 no.3
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• pp.14.1-14.10
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• 2016

Isoelectric solubilization/precipitation (ISP) processing allows selective, pH-induced water solubility of proteins with concurrent separation of lipids and removal of materials not intended for human consumption such as bone, scales, skin, etc. Recovered proteins retain functional properties and nutritional value. Four roe protein isolates (RPIs) from yellowfin tuna roe were prepared under different solubilization and precipitation condition (pH 11/4.5, pH 11/5.5, pH 12/4.5 and pH 12/5.5). RPIs contained 2.3-5.0 % moisture, 79.1-87.8 % protein, 5.6-7. 4 % lipid and 3.0-3.8 % ash. Protein content of RPI-1 and RPI-2 precipitated at pH 4.5 and 5.5 after alkaline solubilization at pH 11, was higher than those of RPI-3 and RPI-4 after alkaline solubilization at pH 12 (P < 0.05). Lipid content (5.6-7.4 %) of RPIs was lower than that of freeze-dried concentrate (10.6 %). And leucine and lysine of RPIs were the most abundant amino acids (8.8-9.4 and 8.5-8.9 g/100 g protein, respectively). S, Na, P, K as minerals were the major elements in RPIs. SDS-PAGE of RPIs showed bands at 100, 45, 25 and 15 K. Moisture and protein contents of process water as a 2'nd byproduct were 98.9-99.0 and 1.3-1.8 %, respectively. Therefore, yellowfin tuna roe isolate could be a promising source of valuable nutrients for human food and animal feeds.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.5
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• pp.473-480
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• 2017

We investigated the nutritional characteristics of the uncooked Skipjack tuna Katsuwonus pelamis frame (U-STF) as a basic resource for preparing flavor-enriching concentrates. The bone rate based on the fish frame (FF) was 53.2% in U-STF, thus lower than those of cooked skipjack tuna frame (C-STF), the uncooked salmon frame (U-SF), and beef leg bone (BLB). The composition of FF had 48.6-58.0% moisture, 18.4-21.3% crude protein, 7.0-15.0% crude lipid, and 12.8-22.1% ash. Compared to the proximate composition of BLB, that of FF was higher moisture and crude protein but lower solids, crude lipids, and ash. The total amino acid contents of FF was 17.6-20.8 g/100 g, which was higher than that of BLB. The levels of calcium and phosphorus of FF were 4.7-8.5 g/100 g and 2.4-4.2 g/100 g, respectively, thus lower than those of BLB. The brix concentration of FF extract was $5.0-8.2^{\circ}$, being highest in U-STF extracts, followed by extracts of U-SF and then extracts of C-STF. Our results indicate that U-STF is an optimal resource for preparing flavor-enriching concentrates.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.3
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• pp.207-212
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• 2001

Supercritical fluid extraction was explored as a method for removing lipids and bad odor from tuna viscera. Selected conditions of extraction pressure, time, temperature and sample size were evaluated for effective removal of lipids and bad odor, Supercritical carbon dioxide was used as a solvent and the extraction was performed at semi-batch flow type. The experimental conditions used in this work was the range of pressure from 1,500 psig to 2,000 psig, the temperature from $25^{\circ}C\;to\;40^{\circ}C$ and dried sample size from 0.2 mm to 1.0 mm. The main fatty acids extracted from tuna viscera were palmitic acid (16: 0) heptadecenoic acid (17: 1) oleic acid (18: 1) and docosahexaenoic acid (22: 6). Protein concentrate was obtained without deformation the optimum condition at $35^{\circ}C$, 1,800 psig and 0.25 mm of the size. In the concentrate after supercritical carbon dioxide extraction, the major amino acids were glutamic acid, leucine and lysine.