• Mass Spectrometry Letters
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• v.9 no.4
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• pp.100-104
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• 2018

As a part of efforts to establish the positive list system (PLS) in South Korea, a method to determine residual emamectin benzoate (EB) in various aquatic products using QuEChERS-EDTA and LC-MRM was developed. The developed method was validated in the aspects of specificity, linearity (correlation coefficient of at least 0.996), sensitivity (the limit of detection and the lower limit of quantitation ${\leq}5ng/g$), recovery (the recovery range of 87.4 and 96.2), and precision (the relative standard deviation of recovery between 0.9 and 13.5). Additionally, the validated method was successfully applied for monitoring EB contamination in eel, halibut, and shrimp collected from local food markets. To our knowledge, the present method is the first one to determine residual EB in various aquatic products at the level satisfying the PLS and could contribute to the establishment of the PLS in South Korea.

• Mass Spectrometry Letters
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• v.12 no.1
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• pp.11-15
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• 2021

Nitarsone is an organoarsenic antiprotozoal drug widely used to treat blackhead disease in turkeys and chickens. However, since its biological conversion into inorganic arsenic, a carcinogen was known, its residue in foods should be regulated. Thus, here, a novel method to determine residual nitarsone in various food commodities (pork, milk, egg, halibut, eel, and shrimp) using QuEChERS and LC-MRM was developed. The developed method was successfully validated through specificity, linearity (coefficient of determination, at least 0.991), recovery (R, 63.6 - 85.6%), precision (the relative standard deviation of R, 0.5 - 10.6%), and sensitivity (the lower limit of quantitation, 5 ppb) by following the Ministry of food and drug safety (MFDS) guidelines. The present method is the first mean to quantitate nitarsone using LC-MRM, and it was designed to be conveniently merged into a new method to quantitate multiple veterinary drugs for the positive list system (PLS). Therefore, the present method could contribute to fortify the food safety system in South Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.3
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• pp.230-237
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• 2018

This study investigated the food and nutritional characteristics of alkaline-insoluble fractions (AIFs) recovered from bastard halibut Paralichthys olivaceus (BH) and skipjack tuna Katsuwonus pelamis (ST) roes using the alkaline solubilization. The moisture content of AIFs ranged from 4.8% to 12.8%, and ST provided significantly better yields (9.5 for STAIF-11 and 7.1 g/100 g roe for STAIF-12) than did BH (P<0.05). The protein content of AIFs ranged from 71.7% to 79.2%, with the highest level yielded by STAIF-11 (6.8 g/100 g roe). The crude fat content of AIFs was 10.9-14.3% and the mineral content was 0.7-3.4%. The major mineral components of AIFs were sulfur, sodium, potassium, and phosphorus. Color values showed that BHAIFs were significantly brighter than STAIFs. Total contents of essential amino acids were significantly higher in STAIFs (47.5-49.5%) than in BHAIFs. The major essential amino acids found in AIFs from both sources were Val, Leu, Lys, and Arg. Therefore, AIFs were significantly superior to whole BH roe in terms of physicochemical and nutritional status, and we identified species-specific differences between BH and ST. Protein is a major component of AIFs recovered from fish roes, which suggests that they have potential for use as a protein source.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.2
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• pp.165-173
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• 2020

Fish roe is among the most valuable food resources produced by fisheries. Raw fish roe requires processing for conversion into hygienic, marketable, and consumer-acceptable forms. In this study, to investigate the food compositional characteristics of various types of fish roe, we applied vacuum freeze-drying to prepare fish roe concentrates (FRCs) from roe of Alaska pollack Theragra chlcogramma, bastard halibut Paralichythys olivaceus, and skipjack tuna Katsuwonus pelamis. The FRC yield ranged from 22.7 to 26.7 g/100 g roe. The major constituents of FRCs were protein (65.4-79.6%), moisture (2.8-6.2%), lipids (8.5-18.3%), and ash (4.8-7.2%). Potassium, sulfur, sodium, and phosphorus were the major mineral elements of FRCs, and the major amino acids were aspartic acid (9.0-10.4 g/100 g protein), glutamic acid (13.2-14.5 g/100 g protein), lysine (8.4-8.6 g/100 g protein), and leucine (8.3-9.7 g/100 g protein). Vacuum freeze-dried FRCs differed among fish species in terms of amino acid composition and electrophoresis protein band distribution. Therefore, FRCs are an excellent source of protein nutrition and an appropriate protein fortification material in human foods or animal feed.

• Applied Microscopy
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• v.32 no.2
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• pp.121-129
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• 2002

The structure of integumentary epidermis is studied in the bastard halibut, Paralichthys olivaceus based on the light and transmission electron microscope. Epidermal layer consists of supporting cells, unicellular glands and accessory cells. The supporting cells were classified into superficial cell, intermediated cell and basal cell. Superficial cell of epidermal layer is squamous or cuboidal and the surface is covered with numerous microridges. The supporting cells are connected to another cell with membrane interdigitations and desmosmes. And tonofilaments are developed in the cortical cytoplasm. Gland cells are classified into mucous cell and club cell. By the histochemical studies of the epidermal secretions the mucous materials are identified as neutral polysaccharides. Club cell has numerous vacuoles and microfilaments in the cytoplasm. Also chloride cells are observed in the epidermis, it cytoplasm is occupied numerous mitochondria.

• Fisheries and Aquatic Sciences
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• v.2 no.1
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• pp.8-11
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• 1999

The optimum boiling condition was determined for fish extracts by response surface model. Model equations were designed with effect of time (T) and the amount of added water (W) on the level of released free amino acid. Based on the high (>0.9) coefficient of determination and low (<0.01) level of significant, those model was approved to be significant. The added water amount of higher regression coefficient $ (\beta_2)$, showed a greater influence on releasing free amino acids than boiling time. The optimum boiling times are 6 hours for crucian carp, 5 hours for bastard halibut, 7 hours for loach and 5 hours for jacopever. The ratio of added water to sample 1 (v/w) could be applied to all fish samples at $100\pm2^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.1
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• pp.93-101
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• 1998

In order to improve the functional properties of several fish meat extracts as an alternate protein source, theri basic plastein reactions were evaluated. The UV absorption at 270 and 290 nm indicated that plasteins had higher amount of hydrophobic peptide or amino acid than the fish meat extracts. The water solubilities of the extracts were reduced at acidic pH. Values for the emulsifying capacity of the extracts and plasteins were over 30% although the latter showed the higher ones than the former. The osmolalities of the extracts at 1.0% concentration were 39(loach), 33(bastard halibut), 30(jacopever) and 24(crucan carp) milliosmole. Generally the slightly higher osmolalities were noted in the plasteins to be compared with the extracts. Both the extracts and plasteins exhibited a higher antioxidative effect than tocopherol. The hydrophobic amino acid which had been introduced at plastein reaction attributed the stronger antionxidative effect of its product than the extracts.

• Journal of Aquaculture
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• v.20 no.3
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• pp.199-202
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• 2007

We isolated a 317 bp of partial cDNA for doublesex-and mab-3-related transcription factor-1 (DMRT-1) from the testis of olive flounder, Paralichthys olivaceus using RT-PCR. Based on the multiple sequence alignment, olive flounder DMRT-1 shared relatively high sequence homology (82 to 94%) with orthologues from other teleost species such as Atlantic halibut, Hippoglossus hippoglossus, black porgy, Acanthopagrus schlegeli and rainbow trout, Oncorhynchus mykiss. DMRT-1 mRNA was predominantly expressed in the testis of olive flounder. In our investigation for the effect of testosterone treatment in vivo on induced expression of ovarian DMRT-1 transcript, mRNA levels of DMRT-1 in ovary were significantly up-regulated by testosterone treatments (0.3 or $3.0{\mu}g$ testosterone/g body weight for 12 to 36 hours) as judged by RT-PCR analysis. In overall, transcriptional stimulation of DMRT-1 during treatments was more affected by doses of testosterone than treatment durations. This result strongly suggests that the regulation of DMRT-1 be tissue- and gender-specific in olive flounder, and also provides useful baseline knowledge on the testosterone-mediated regulation in the reproductive physiology of this species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.6
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• pp.694-706
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• 2017

This study evaluated the protein recovery, functional properties and biological activity of isolate processed water (IPW) generated in the preparation of protein isolates from fish roes (BH, bastard halibut Paralichthys olivaceus; ST, skipjack tuna Katsuwonus pelamis; YT, yellowfin tuna Thunnus albacares) by an isoelectric solubilization and precipitation process. The IPWs contained 2.7-5.4 mg/mL of protein, and the protein losses were 8-21% (P<0.05). The form capacity of IPW-3 for BH and ST, and IPW-4 for YT was 155, 194, and 164%, respectively. The emulsifying activity index ($27-43m^2/g$) of the YT-IPWs was the strongest, followed by ST ($7-29m^2/g$) and BH ($10-19m^2/g$). The 2,2-diphenyl-1-picrylhydrazyl scavenging activities of IPW-1 and -3 were higher than those of IPW-2 and -4. The 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid scavenging activity ($IC_{50}$, mg/mL) of IPW-2 and -4 was 0.03 mg/mL for BH, 0.04-0.08 mg/mL for ST, and 0.04-0.07 mg/mL for YT. BH IPW-3 had the strongest reducing power (0.41 mg/mL) and superoxide dismutase-like activity (1.68 mg/mL). The angiotensin-I converting enzyme inhibitory activity of IPW-3 was the highest for ST (1.52 mg/mL), followed by BH and YT. The common predominant amino acids in the IPWs were the essential amino acids Val, Leu, Lys, and Arg and the non-essential amino acids Ser, Glu, and Ala.

• Preventive Nutrition and Food Science
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• v.4 no.1
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• pp.23-27
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• 1999

To evaluate the quality of fish extracts with spicy vegetables (garlic, onion and ginger) in suppressing fishy oder, fish extracts of crucian carp, loach, bastard halibut and jacopever were processed at 100 $^{\circ}C$ for 6 hours, and their in vitro and in vivo protein qualities were determined . Protein and total lipid contents were closely related to the degree of discarding floated lipid on fish extracts and the kinds of added apicy vegetables . Boiling (10$0^{\circ}C$) , appeared to improve in vitro protein qualities slightly more than hydrocooking (11$0^{\circ}C$), but those with mild processing tended to result in better protein qualities than high temperature cooking (136-14$0^{\circ}C$). Spicy vegetables did not have remarkable effects on improving in vitro protein quality parameters. Fish extracts with 10% ginger were generally higher in in vitro protein quality than with the other vegetables . In spite of higher in vivo protein digestibility of fish extracts containing spicy vegetables processed under mild conditions(10$0^{\circ}C$), PERs of those extracts were not higher htan those of extranct processed at high temperature.