• 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 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.

• 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 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.