Food Science and Biotechnology
→ Food Science and Biotechnology 2018 ; 27(1): 87-93
Tyramine reduction by tyrosine decarboxylase inhibitor in Enterococcus faecium for tyramine controlled cheonggukjang
Hyang-Rin Kang1, Ho-Sik Kim1, Jae-Hyung Mah1, Young-Wan Kim1, Han-Joon Hwang1
1Department of Food and Biotechnology, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City 339-700, Korea
This study was carried out to find a method to control tyrosine decarboxylase activity (TDC) of a strain of Enterococcus faecium capable of producing high levels of tyramine. To select a TDC inhibitor, enzyme assay was first performed using purified TDC enzyme and 0.1% of TDC inhibiting chemicals. When 0.23% of nicotinic acid was added, tyramine content (363 ug/mL) was lower than that of the control group (873 ug/mL). At the same time, bacterial growth was decreased 1 log cycle from 8.62 to 7.56 log CFU/mL. TDC expression level in E. faecium was measured by using RT-qPCR. Lower expression level (below 0.7) was observed after the addition of 0.23% nicotinic acid (in vitro). When cheonggukjang was manufactured with addition of nicotinic acid, tyramine contents were decreased from 698.67 to 117.27 mg/kg when the concentration of nicotinic acid added was increased from 0.10 to 0.30%. These results suggest that nicotinic acid could be used as an agent (TDC inhibitor) to reduce tyramine content in cheonggukjang.
Tyramine, Biogenic amine, TDC, TDC inhibitor, Choenggukjang
Food Science and Biotechnology 2018 ; 27(1): 87-93