• Journal of the Korean Society of Food Culture
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• v.23 no.3
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• pp.397-402
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• 2008

This study was conducted to evaluate the quality characteristics of domestic as well as imported fermented skate. Three types of fermented skate products were analyzed for proximate composition, pH, VBN, ammonia-N, free amino acids, and fatty acids. The results indicated that the domestic fermented skate contained large amounts of TMAO. Also, the domestic and imported fermented skates each contained approximately 7.1 log CFU/g and $5.8{\sim}6.5$ log CFU/g of aerobic bacteria, respectively, and 585.9 mg and $384.1{\sim}398.5$ mg of total free amino acids, respectively; all samples contained high levels of taurine, anserine, lysine, alanine, glycine, proline, and ${\beta}-alanine$. For fatty acid composition, the domestic fermented skate contained 11 different types of saturated fatty acid and 16 types of unsaturated fatty acid, whereas the imported skate contained 8 types of saturated fatty acid and $10{\sim}15$ types of unsaturated fatty acid. Overall, the results suggest that domestic fermented skate is a better source of amino acids and essential fatty acids and contains more aerobic bacteria than imported fermented skate.

• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.438-444
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• 2010

Fermented skate has a unique ammonia-like flavor. The flavor is preferred by a few lovers of skate muscle, while women and young people may be sensitive to the odor. Organic acids were used to reduce the ammonia-like odor in fermented skate and to investigate the physicochemical properties. Fermented skate muscles were sprayed with 20 mL of acetic acid or citric acid (3, 5, and 7%) for 30 seconds and stored at $4^{\circ}C$ for 15 days. The physicochemical properties of organic acid-treated fermented skate were investigated during storage. The control, which was treated with distilled water, showed a higher pH value than the samples treated with organic acids. The $L^*$ value increased with increasing organic acid concentration, while the $a^*$ and $b^*$ values were not significantly different among the samples. The trimethylamine (TMA) decreased with increasing in the organic acid concentration, but it was not significantly different after 9 days of storage. Ammonia-type nitrogen and ammonia-like flavoring, decreased with increasing in the organic acid concentration, whereas ammonia-type nitrogen increased with a storage period more than 6 days. In conclusion, fermented skate treated with 7% citric acid was the best treatment to reduce the ammonia-like odor.

• Microbiology and Biotechnology Letters
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• v.38 no.3
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• pp.322-328
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• 2010

Fermented skate is a traditional Korean food popular in Southwestern area of Korea. It has a characteristic flavor and alkaline pH. In this study we tried to determine the microbial flora in fermented skate using two different approaches. In culture-independent method, we amplified V2 region of 16S rRNA gene by PCR and cloned them into pUC18 plasmid to construct 16S rDNA fragment library. BLAST searches for the sequences obtained from this library revealed that uncultured bacterium clone 054E11.b was the most dominant flora in this fermented fish. In culture-dependent method, we diluted suspension of skate and spreaded on MRS, PCA, and MacConkey plates. We identified colonies grown on those plates by using PCR amplification of V2 region of 16S rRNA and DNA sequencing. BLAST searches of those DNA sequences resulted in totally different species with the observations from the 16S rDNA library analysis. Discrepancies of results obtained from both approaches suggest that the agar plates used in culture-dependent method may be different from the real condition of fermented skate. Therefore, results from culture-independent approach using 16S rDNA fragment library analysis may reflect real microbial flora in fermented skate.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.3
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• pp.202-212
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• 2020

In order to replace sardine baits for octopus pot, an efficacy experiment to lure with alternative bait (fermented skate or chicken skin in artificial crab or northern clam) pots and sardine pot were conducted in a circular water tank. The soaking time of the sardine bait was divided into two categories: six days or less and seven days or more. The behavioral response of octopus to the artificial bait pots and sardine pot were investigated. In the comparison of the luring effects between pots with fermented skate inside artificial crab or northern clam and sardine pot, the pot with artificial crab + fermented skate had better results than the other pots in the section distribution (31.6%) and the number of times the pot was entered into (20.0%) (p > 0.05). In the comparison of the luring effects between pots with chicken skin inside artificial crab or northern clam and sardine pot, the pot with northern clam + chicken skin had better results than the other pots in the section distribution (22.6%) and number of times the pot was entered into (55.6%) (p < 0.05). The results were also better compared to those of pot with artificial crab + fermented skate. From these results, it seems that in the luring effect aspect, sardine bait can be replaced with artificial bait consisting of chicken skin inside northern clam.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.9
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• pp.141-146
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• 2015

Recently, people are consuming more fermented food for its health benefits. When we think of fermented food, skate comes to mind. However, there are different preferences depending on the degree of fermentation. Thus, if there is a system that shows the degree of the fermentation on skate, people can eat according to their taste. This paper proposes a design of skate fermentation monitoring system for consumer taste using the smart RFID tag. The proposed system consists of the RFID tag, $NH_3$ sensor, reader, and server. In order to confirm the usefulness of the proposed system, we performed experiments on the skate fermentation. The proposed monitoring system can show the skate fermentation at 4 grades: None, Low, Medium, and Strong. With the smart RFID tag, we successfully estimated the skate fermentation.

• Journal of Food Hygiene and Safety
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• v.23 no.2
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• pp.137-141
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• 2008

To evaluate safety of commercial skate product, Korean traditional ready-to-eat raw-fish, during from June to August in 2006, microbial and chemical properties such as levels of total plate count, coliform, food-borne pathogens, VBN-value, pH and ammonium concentration in ready-to-eat skate product were evaluated. Total plate counts of ready-to-eat skate product were ranges from 4.8 to 7.5 log CFU/g, and coliform was detected in 1 sample (2.48 log CFU/g) among 18 samples. Staphylococcus aureus, was detected in 2 samples among 18 samples, but Escherichia coli, Salmonella, spp., Vibrio parahaemolyticus, and Listeria monocytogenes were not detected. VBN-values and pH of skate were ranges from 12.6 to 593.9 mg% and from 6.7 to 9.4 depending on strength of fermentation, respectively. Ammonium concentrations of fermented skate were ranges from 4.4 to 14.1 mg/g and 2 samples, pre-fermented skate, were not detected.

• Journal of Life Science
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• v.13 no.5
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• pp.675-683
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• 2003

This study was conducted to investigate the physiological properties of various parts of skate body after fermentation by measuring compositional properties including pH and $NH_4^+$. Other functional properties, such as antibacterial activities, antioxidative activities and anticancer activities were measured. Effects of fermentation temperature (4, 10, $20^{\circ}C$) did not affect compositional properties of fermented skate. The pH of fermented skate extract at 4$^{\circ}C$ did not increase as much as that at 10 and $20^{\circ}C$, Particularly at $10^{\circ}C$, the pH increased rapidly after Day 1 and remained unchanged until another increase at Day 5. At 2$0^{\circ}C$, the pH increased rather rapidly at early stage of fermentation and reached 8.9 at Day 4. The pattern of $NH_4^+$ concentration of fermented skate extract was similar to that of pH. Particularly at $4^{\circ}C$ fermentation, $NH_4^+$ concentration was not affected by fermentation time. The concentration of $NH_4^+$. reached approximately $10.2\mug/mL$at $10^{\circ}C$ for Day 5 and $20^{\circ}C$ for Day 4-5, indicating the early stage of fermentation. According to physiological activities of hot water extracts of skate fillet and viscera as affected by fermentation time, antibacterial activity of 2% viscera extract concentration was 43.3% at Day 8, while there was no antibacterial activity from fillet extract. As for the antioxidative activity, fillet extract and viscera extract both at 2% concentration at Day 0 showed 61.2% and 54.4%, respectively. Anticancer activities were highest (52.7% for fillet extract and 58.3% for viscera extract) at $1,000 \mug/mL$ concentration at Day 8. Antibacterial activities and anticancer effects were relatively high as fermentation was progressed, while antioxidative activities were highest before fermentation started. As for the physiological activities of hot water extract from brain and cartilage, antibacterial activities were observed at 41.0% when 2% brain extract was added at 4 hours of incubation, while 35.8% with 2% cartilage extract at 14 hours of incubation. Antioxidative activities were not found in brain extract, but cartilage extract at 2% showed 25.0% of antioxidative activity, which was lower than fillet and viscera extract.

• Journal of Microbiology and Biotechnology
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• v.30 no.8
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• pp.1195-1206
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• 2020

Beringraja pulchra, Cham-hong-eo in Korean, is a mottled skate which is belonging to the cartilaginous fish. Although this species is economically valuable in South Korea as an alkaline-fermented food, there are few microbial studies on such fermentation. Here, we analyzed microbial changes and pH before, during, and after fermentation and examined the effect of inoculation by a skin microbiota mixture on the skate fermentation (control vs. treatment). To analyze microbial community, the V4 regions of bacterial 16S rRNA genes from the skates were amplified, sequenced and analyzed. During the skate fermentation, pH and total number of marine bacteria increased in both groups, while microbial diversity decreased after fermentation. Pseudomonas, which was predominant in the initial skate, declined by fermentation (Day 0: 11.39 ± 5.52%; Day 20: 0.61 ± 0.9%), while the abundance of Pseudoalteromonas increased dramatically (Day 0: 1.42 ± 0.41%; Day 20: 64.92 ± 24.15%). From our co-occurrence analysis, the Pseudoalteromonas was positively correlated with Aerococcaceae (r = 0.638) and Moraxella (r = 0.474), which also increased with fermentation, and negatively correlated with Pseudomonas (r = -0.847) during fermentation. There are no critically significant differences between control and treatment. These results revealed that the alkaline fermentation of skates dramatically changed the microbiota, but the initial inoculation by a skin microbiota mixture didn't show critical changes in the final microbial community. Our results extended understanding of microbial interactions and provided the new insights of microbial changes during alkaline fermentation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.3
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• pp.275-283
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• 2015

This study compared the sensory and nutritional characteristics of mottled skate Beringraja pulchra caught off Ulleung Island (U-MS), Korea, with those caught off Daecheong Island (D-MS). Based on their trichloroacetic acid-soluble nitrogen content, free amino acid content, and taste value, the taste of intermediate weight female U-MS was superior to that of both other U-MS and D-MS. The urea content of U-MS was higher in females than males and increased in the order heavy>intermediate>light individuals. There was, however, no difference in urea content between U-MS and D-MS. The taste and flavor characterization results suggest that the level of ammonia, which was converted from urea, influenced the quality of fermented U-DS. With the exception of the light U-DS, the other U-MS exhibited no difference in terms of hardness. The total amino acid content of U-MS was higher in females than males and increased in the order intermediate > heavy > light individuals. The total amino acid content of U-MS was also higher than that of D-MS. The major amino acids of all MSs were aspartic acid, glutamic acid, leucine, and lysine.

• Journal of the Korean Society of Food Culture
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• v.23 no.2
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• pp.235-242
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• 2008

In this study, the physicochemical and microbiological properties of market-available skate (Raja kenojei) kimchi were evaluated in comparison to long-term fermented Baechu kimchi. The comparative results for the skate (Raja kenojei) and Baechu kimchi products are as follows: salt concentrations = 3.40% and 3.95%, respectively; pH and acidity values = 4.01 and 3.90, and 0.65% and 0.82%, respectively; redox potential Eh values = 119.82 mV and 123.08 mV respectively; reducing sugars levels = 15.51 mg% and 13.23mg%, respectively; ascorbic acid levels = 24.21mg% and 22.18mg%, respectively; color L-values = 46.86 and 44.54, a-values = 15.46 and 12.28, and b-values = 29.94 and 28.36, respectively; hardness properties = 11.36 kgf and 10.23 kgf, respectively; hot water soluble pectin (HWSP) contents and sodium hexametaphosphate soluble pectin (NaSP) contents = 15.23% and 17.35%, and 32.51% and 29.64%, respectively; hydrochloric acid soluble pectin (HClSP) contents = 55.1% and 53.2%, respectively; total viable cell counts = $4.78{\times}10^8$ and $1.35{\times}10^8$, respectively; lactic acid bacteria counts = $5.18{\times}10^5$ and $1.32{\times}10^5$, respectively; and yeast levels = $8.52{\times}10^5$ and $5.23{\times}10^5$, respectively.