천연물 및 초정수압 처리에 의한 고등어 내의 Histidine Decarboxylase 저해 활성

Abstract

Mackerel (Scomber japonicus) is the most consumed fish species by the consumer in several continue of the world. However, these mackerel can cause food poisoning such as Scombroid fish poisoning by histamine which generated through the process of distribution and preservation. Free histidine in mackerel muscle is transformed into the histamine by microorganisms producing histidine decarboxylase (HDC). Scombroid fish poisoning is one type of food poisoning with allergy-like symptoms and exhibits the toxicty when it ingested to human body at large quantities. Therefore, to prevent food poisoning caused by the consumption of mackerel, main attention should be a focused on the preservation and control of histamine. Thus, this study was performed to investigate the inhibitory effects of natural materials and high hydrostatic pressure treatment on histamine production in mackerel. At first, changes in viable cell counts, histamine contents, pH and VBN of mackerel fillet treated with ethanol extracts of Ecklonia cava (EC) and Eisenia bicyclis (EB) were measured at 4℃. As a result, viable cell counts were no difference between the untreated and treated sample. The mackerel fillet with added EC/EB extracts had reduced growth of viable cell counts by 2 log cycles after 10 days. Histamine contents of mackerels treated with EC and EB extracts were measured. The histamine contents were decreased by EC and EB extracts (115 and 96 ppm) compared to control at 5 days (384 ppm). The pH of mackerels treated with EC and EB extracts were no difference while pH of the control was increased during storage. Furthermore, VBN of mackerels treated with EC and EB extracts were significantly decreased compared to the control. Secondly, viable cell counts, histamine contents, pH and VBN of mackerel fillet treated with high hydrostatic pressure (2000, 3000 and 4000 bar) were measured at 4℃. The high hydrostatic pressure(HHP) inhibited the growth of viable cell after 5 days over 3000 bar. Especially, the viable cells of mackerels treated with 4000 bar did not appear. Histamine contents of mackerels was significantly decreased by HHP. Furthermore, mackerels treated with HHP showed significantly lower VBN values as compared to the control and the pH was not affected by HHP during storage. These suggest that the adding natural materials extracts and HHP treatments to mackerel decreased histamine contents in mackerel muscle. To verify effects of natural materials and HHP treatments on histamine production, histidine decarboxylase produced by Morganella morganii was purified by ammonium sulfate with salting-out, dialysis, DEAE-sephadex, aminohexyl-sepharose and sephacryl S-300 HR column (specific activity : 250.81 U/mg). E. cava and E. bicyclis ethanol extracts against purified HDC from M. morganii showed high inhibitory activity. Especially, dieckol separated from E. bicyclis ethanol extract showed high inhibitory activity with IC50 value of 0.51 mg/mL. The purified HDC treated with HHP showed lower activity depending on increasing pressure. Therefore, E. cava and E. bicyclis ethanol extracts and HHP treatment may reduce scombroid fish poisoning by decreasing histamine production in mackerel.