• Fisheries and Aquatic Sciences
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• 제24권2호
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• pp.78-88
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• 2021

The annual consumption of fishery products, particularly sea squirt (Halocynthia roretzi), per person has steadily increased in South Korea. However, the quantitative risk of Vibrio parahaemolyticus following intake of sea squirt has not been analyzed. This study focuses on quantitative predictions of the probability of consuming sea squirt and getting of V. parahaemolyticus foodborne illness. The prevalence of V. parahaemolyticus in sea squirt was evaluated, and the time spent by sea squirt in transportation vehicles, market displays, and home refrigerators, in addition to the temperature of each of these, were recorded. The data were fitted to the @RISK program to obtain a probability distribution. Predictive models were developed to determine the fate of V. parahaemolyticus under distribution conditions. A simulation model was prepared based on experimental data, and a dose-response model for V. parahaemolyticus was prepared using data from literature to estimate infection risk. V. parahaemolyticus contamination was detected in 6 of 35 (17.1%) sea squirt samples. The daily consumption quantity of sea squirt was 62.14 g per person, and the consumption frequency was 0.28%. The average probability of V. parahaemolyticus foodborne illness following sea squirt consumption per person per day was 4.03 × 10^-9. The objective of this study was to evaluate the risk of foodborne illness caused by Vibrio parahaemolyticus following sea squirt consumption in South Korea.

• 한국수산과학회지
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• 제46권1호
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• pp.27-36
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• 2013

This study was conducted to develop and characterize sea squirt Halocynthia roretzi sikhae. According to the results for pH, total acidity, lactic acid bacteria, amino nitrogen and sensory evaluation of sea squirt sikhae during fermentation for 6 days at $15^{\circ}C$, the optimum fermentation periods were 4 days for sourness-disliking customers and 5 days for sour-disliking customers. No differences in the proximate compositions of sea squirt sikhaes fermented for 4 days (4D) and for 5 days (5D) were found. There was a difference in the eproximate compositions of commercial seasoned sea squirts, 4D and 5D, sea squirt sikhaes. The results of salinity, total acidity, amino nitrogen and sensory evaluation of two kinds of sikhae suggest that the taste was stronger for 5D than for 4D, both of which were superior to commercial seasoned sea squirts. There was, however, no difference in color of 4D, 5D and commercial seasoned sea squirts. The results of E. coli analyses suggest that sea squirt sikhae is a safe food in terms of sanitation.

• 한국양식학회지
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• 제1권1호
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• pp.75-84
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• 1988

1984년 2월부터 1986년 7월까지 한산도 앞바다에서 우렁쉥이 성장을 조사한 결과는 다음과 같다. 체고의 성장에 있어서는 실험개시시 평균체고 0.5 mm에서 25경월후에는 9.15 cm로 자랐다. 육중의 성장은, 1985년 2월부터 1986년 3월까지의 13개월만에 1.27 g에서 41.69 g으로 증중하였다. 수온이 높고 (평균 $23.53^{\circ}C$), 해수비중이 낮은 (평균 1.0233)시기인 여름철에는 길이나 무게가 감소하는 경향을 보였다. 체고에 대한 체폭의 상대성성비는 양식기간에 따른 성장과 더불어 낮아져서 우렁쉥이의 모양이 점차 장형이 되는 경향을 보였다. 월별 우렁쉥이 폐사율은 6월과 7월에 비교적 높은 편이었으며, 전체적으로 보면 $10.83\%$였다.

• 한국식품위생안전성학회지
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• 제35권1호
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• pp.51-59
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• 2020

본 연구에서는 V. vulnificus와 V. cholerae를 중심으로 국내에서 유통되는 우렁쉥이에 대한 위해평가를 실시하였다. 위험성 확인 단계에서 병원성 비브리오균의 위험성에 대해 조사하였고, 노출평가 단계에서는 초기오염도를 산출하기 위하여 네 권역에서 우렁쉥이의 병원성 비브리오균 오염실태를 조사하였다. 또한 대형할인마트, 시장 및 횟집에서 관리자와의 면담을 통하여 유통 시간을 조사하였으며, 시료의 품온 및 진열대 온도를 직접 측정하여 유통 온도를 수집하였다. 예측모델 개발을 위하여 병원성 비브리오 균을 혼합하여 우렁쉥이에 접종 후 다양한 온도(7℃, 10℃, 15℃, 20℃)에 저장하면서 시간대별로 꺼내어 세균의 생장 및 사멸을 확인하였다. 섭취자 비율 및 섭취량은 2016년 국민건강영양조사 원시자료를 활용하여 산출하였으며 용량-반응모델 선정을 위하여 문헌조사를 실시하였고, 최종적으로 수집된 데이터들을 활용하여 시나리오를 구성하였다. 오염실태 조사 결과 V. vulnificus는 검출되지 않았으며 V. cholerae는 101개의 시료 중 1개에서 양성으로 검출되었다. 유통환경조사 결과 우렁쉥이는 최소 1시간, 최대 48시간까지 진열되는 것으로 조사되었고 0-10℃로 유통되는 것을 확인하였다. 예측모델 개발 결과 모든 온도(7℃, 10℃, 15℃, 20℃)에서 병원성 비브리오균은 점차 사멸하는 경향을 띄었으며 개발된 모델의 적합성 검증결과 RMSE값이 0에 가까워 개발된 모델이 우렁쉥이에서 병원성 비브리오 균의 균주 변화를 묘사하기에 적합하다고 판단되었다. 섭취자 비율 및 섭취량은 0.26% 및 65.13 g으로 나타났으며 용량-반응 모델은 Beta-Poisson 모델을 사용하였다. 최종적으로 @RISK Fitting 프로그램을 활용하여 위해도를 추정한 결과, 우렁쉥이를 섭취하였을 경우 1일 1인에게서의 V. vulnificus로 인한 식중독 발생 확률은 평균 2.66×10^-15, V. cholerae로 인한 식중독 발생 확률은 평균 1.02×10^-12으로 추정되었다. 또한 민감도 분석결과 섭취자 비율이 위해도에 가장 큰 양의 상관관계를 나타내는 것으로 조사되었다. 해당 연구결과는 국내 우렁쉥이 유통과정에서 병원성 비브리오균에 대한 안전한 수산물을 생산하는데에 기여할 수 있을 것으로 판단된다. 또한 위해 평가 결과는 국내 수산물에서 V. vulnificus와 V. cholerae에 대한 기준·규격을 설정하는데 기초자료로 활용할 수 있을 것으로 사료된다.

• Journal of Microbiology and Biotechnology
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• 제18권9호
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• pp.1510-1517
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• 2008

Expresssed sequence tag (EST) analysis was developed from three cDNA libraries constructed from cells of the digestive tract, gonad, and liver of sea squirt. Randomly selected cDNA clones were partially sequenced to generate a total of 922 ESTs, in which 687 unique ESTs were identified respectively. Results of BLASTX search showed that 612 ESTs (89%) have homology to genes of known function whereas 75 ESTs (11%) were unidentified or novel. Based on the major function of their encoded proteins, the identified clones were classified into ten broad categories. We also identified several kinds of immune-related genes as identifying novel genes. Sequence analysis of ESTs revealed the presence of microsatellite-containing genes that may be valuable for further gene mapping studies. The accumulation of a large number of identified cDNA clones is invaluable for the study of sea squirt genetics and developmental biology. Further studies using cDNA microarrays are needed to identify the differentially expressed transcripts after disease infection.

• 한국수산과학회지
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• 제46권6호
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• pp.813-818
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• 2013

In order to understand the co-culture impact of the sea squirt Halocynthia roretzi on the Pacific oyster Crassostrea gigas, we examined the filtration rate of the sea squirt in relation of water temperature ($5-25^{\circ}C$) and body weight. The filtration rate increased in relation to body weight and water temperature, indicating a clear positive correlation with the two variables. Due to the clear positive correlation between filtration rates at each temperature groups for acceptable collinearity, each constants at regression equation was further analyzed for a unified model of filtration rate. Therefore the filtration rate of H. roretzi was estimated as: Fr (L/h/animal)=$(0.1956+0.0182T){\times}DW^{0.7978EXP(-0.0273T)}$ for water temperature in the range of $5-25^{\circ}C$. The estimated filtration rates of H. roretzi were higher than those of C. gigas in the winter season (water temperatures below $16^{\circ}C$) in condition of equal body weight. Our results indicate that H. roretzi may have an advantage over C. gigas in food competition during the winter season when the two species are co-cultured.

• 한국식품영양과학회지
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• 제24권2호
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• pp.268-273
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• 1995

To study the nutritional value of warty sea squirt, Styela clava, which is one kind of urochoda and it has been used as special seafood stuffs by Korean, the seasonal variations of nutrient was investigated. The moisture content was ranged from 83.6% to 86.8% in experimental period. Maximun glycogen content showed up in June (3.7g/100g sample). The protein(N$\times$6.25) and lipid content varied with glycogen whereas ash content was not changed remarkably, showing 2.8$\pm$0.3%. Predominant minerals in edible portion and integuments were sodium, potassium, calcium and magnesium in order. Predominant constitutiional amino acids were asparagine, glutamic acid, taurine, aspartic acid, lysine and glycine and amino acids occupied 50% of the total amino acid. Porportion of nonpolar lipid to total lipid increased from April to early June while polar lipid level decreased. The neutral lipid was composed of triglyceride(59.32%) and free sterol(23.52%), and followed by diglycerides, monoglycerides, esterified sterols and hydrocarbon, free fatty acid. The phospholipid was mainly composed with phosphatidyl choline(49.7%), and phosphatidyl ethanolamine(33.0%). The major fatty acids of the total lipid in warty sea squirt were C20 : 5(17%), C22 : 6(13.76%), C16 : o(13.91%) and C16 : 1(12.52%).

• 한국수산과학회지
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• 제44권5호
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• pp.516-523
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• 2011

To compare four populations of sea squirt Halocynthia roretzi adults, their egg quality and larval development were investigated in the hatchery. The populations were: south sea wild (SSW), south sea cultured (SSC), east sea wild (ESW) and Iwate Japan cultured (IJC). Egg quality and larval development were compared using 13 factors (fertilization rate and diameter, proximate composition, amino acid and fatty acid contents of eggs, hatching rate and various sizes of tadpole larvae) which were obtained from each population. Fertilized egg diameter, hatching rate and size of tadpole larvae were significantly different among the four populations (P<0.05). Eggs were produced with higher crude protein ($5.20{\pm}0.00%$ SSW, $4.71{\pm}0.01%$ ESW, $4.66{\pm}0.01%$ SSC and $3.96{\pm}0.01%$ IJC) and lipid ($1.22{\pm}0.01%$ ESW, $1.01{\pm}0.00%$ SSW, $0.77{\pm}0.01%$ SSC and $0.69{\pm}0.00%$ IJC,) contents from domestic wild populations than from Japanese or cultured populations. Also amino acid and fatty acid contents were different. The extent of similarity between domestic and Japanese populations (30.5% IJC:SSW, 34.3% IJC:SSC and 40.7% IJC:ESW) was relatively low but was very high between SSW and SSC (73.9%). These results may have been due to differences in the abundance of food types and environmental conditions in the four localities and consequent differences in the diets of the sea squirts.

• 한국수산과학회지
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• 제47권1호
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• pp.1-11
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• 2014

This study was carried out to investigate nutritional and physiologically active characterizations of sikhae and the seasoned products from the sea squirt Halocynthia roretzi. The total taste values of sikhae fermented for 4 and 5 days were 10.9 and 15.4, respectively, which was lower than for commercially seasoned sea squirts. The sikhaes contained mostly glutamic and aspartic acids. The total amino acid contents of sikhaes fermented for 4 and 5 days were 5.5 and 6.0 g/100 g, respectively, which were lower than those of commercial seasoned-sea squirts or similar. An amount of 100 g of sikhae and its seasoned products contained P, K, Mg and Fe, and these minerals, which are deemed good for our health, were at 10% above the recommended daily requirements. The functional properties of sikhae fermented for 4 and 5 days were as follows: for ACE inhibiting activity, 69 and 69.5%, respectively; for antioxidative activity, 28.9 and 29.3%, respectively; for xanthine oxidase inhibitory activity, 52.8 and 53.1%, respectively; and for ${\alpha}$-glucosidase inhibitory activity, 2.4 and 1.4%, respectively. Antimicrobial activity of the 5 day fermented sikhae against Vibrio parahaemolyticus and Staphyloccus aureus was detected in 8 mm and in 7 mm against Escherichia coli.

• 한국수산과학회지
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• 제44권4호
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• pp.366-371
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• 2011

The sea squirt Halocynthia roretzi is mainly cultured in Tongyeong, Southern coastal area of Korea. This study presents the physiological rates of respiration, excretion, feeding and assimilation efficiency of the sea squirt Halocynthia roretzi to analyze the SFG(scope for growth) and net growth efficiency, determined during 2007. Oxygen consumption and nitrogen excretion rates increased with a rise in temperature during the summer period whereas feeding rates decreased. The O:N ratio was high during winter(October to February). Assimilation efficiency showed an annual average of 75.4% during the experimental period, except during a period of elevated temperature in July to September(average $25^{\circ}C$). Net growth efficiency($K_2$) was 8.7 to 64.2% except for May to September, when temperature increased at the aquaculture farm. SFG was negative from May to September, reflecting high temperatures and low feeding rates during this period; its highest positive values occurred during winter.