Yasuyuki Tsukamasa is a Professor in Department of Fisheries in Kinki University.
Raising the temperature of frozen tuna meat from below -40° C to approximately -10° C before thawing has been reported to remove NAD+ and prevent thaw-rigor. If NAD+ is degraded by NADase, glycolysis will cease and a high pH and low met-myoglobin content will be maintained after thawing. Therefore, we attempted to identify conditions that would suppress met-myoglobin formation during cold storage of frozen skipjack tuna meat. B1 skipjack tuna stored at -40° C was used. Temperature shift treatment (TST) was performed by raising the temperature of the meat to -5° C, -6° C, -7° C and -8° C for 24 hours. After TST, samples were stored at 5° C for 2 days with or without vacuum packaging. Regardless of the packaging, 24 hours of TST reduced the NAD+ content. A remarkable decrease in pH from 6.3 to 6.0 was observed in meat stored at -5° C TST; however, the pH of all other TST samples remained stable during storage at 5° C. In contrast, non-treatment groups with and without vacuum packaging showed a major decrease in pH to as low as 5.6. The met-myoglobin content increased remarkably during cold storage in all non-treatment groups with and without vacuum packaging and in all TST groups without vacuum packaging. However, all TST groups including the -5° C with vacuum packaging group maintained the met-myoglobin content at the level measured after 0 hour storage at 5° C. Thus, TST and vacuum packaging are both required to delay met-myoglobin formation. The NADase activity of skipjack tuna meat was also measured.
Gi Dong Han has completed his PhD at the age of 33 years from Niigata University in Japan and postdoctoral studies from Niigat University School of Medicine. He is the Professor of Yeungnam University in South Korea. He has published more than 25 papers in reputed journals and has been serving as an administering board member of Korean Society of Food Science and Technology.
The aim of this study was to assess the ability of Ligulariafischeri (LF) extract to attenuate ethanol-induced oxidative stress accompanied by hepatotoxicity both in vitro and in vivo. LF extract at different concentrations (50 to 500 µg/mL) prevented excessive generation of reactive oxygen species with no cytotoxicity in NCTC-1469 cell lines treated with or without 100 mM ethanol. In vivo study was carried out in an alcohol-fed rat model orally administered ethanol with or without LF extract (100 mg or 200 mg/kg body weight) for 6 weeks. Liver injury markers in serum were attenuated upon LF extract supplementation. Further, LF extract significantly reduced hepatic lipid peroxidation, activated the antioxidant defense system, and down-regulated cytochrome P4502E1 in the liver. Lastly, LF extract treatment reduced expression of pro-inflammatory cytokines and diminished alcohol-induced abnormal morphological changes.