Reduction of Tyramine by Addition of Schizandra chinensis Baillon in Cheonggukjang

Abstract

This study was performed to examine the microorganisms responsible for the high tyramine content of Cheonggukjang, a traditional Korean fermented soy food, and to establish a technology for controlling the growth of these microorganisms. The tyramine content in 13 collected Cheonggukjang samples averaged 604.9 mg/kg. Since the tyramine content measured from most samples was sufficient to cause harm to the human body, it is necessary to control its production in food. Enterococci were confirmed to be the bacterial species producing most of the tyramine through the microbial examination and were present in high numbers from not detected (<10(1)) to 7.0 × 10(10) colony-forming units (CFU)/g. To control the growth of enterococci, various plant extracts with antimicrobial activity, common salts, and variable temperature conditions were tested. It was found that 4 samples among the 159 plant extracts had a strong antimicrobial activity in Cheonggukjang, especially against Enterococcus faecium, showing viable cell counts of <10(1)-10(3) CFU/g after 24 h of ripening, which were significantly lower values compared to the control (10(9)-10(11) CFU/g). The Cheonggukjang with the addition of the four plant extracts showed ∼83%-95% lower concentrations of tyramine compared to the control. Cheonggukjang prepared with the Schizandra chinensis Baillon extract had the lowest tyramine content without sacrificing the sensory quality. Not only was the bacterial species of E. faecium reduced more remarkably, by up to 10(3) CFU/g compared to the 10(9)-10(11) CFU/g shown in the control, but it also decreased the tyramine content by up to 91%.

The Role of Enterococcus faecium as a Key Producer and Fermentation Condition as an Influencing Factor in Tyramine Accumulation in Cheonggukjang

“…Overall, the physicochemical properties of retail Cheonggukjang products analyzed in the current study were mostly similar to the values reported in previous studies. Although the results of the current study did not show any correlation between physicochemical properties and BA content (especially tyramine) based on linear regression analyses (data not shown), it is noteworthy that the ranges of the physicochemical parameters were within the specific conditions for the growth of E. faecium, which are as follows: pH, from 4 to 10 [50]; salinity, up to 7% [50]; water activity, above 0.940 [51]. Table 2 shows the microbial properties of retail Cheonggukjang products.…”

“…x FOR PEER REVIEW 12 of 18 of 42.7 °C[50,70]. The current and previous studies, therefore, indicate that the use of high fermentation temperatures such as 45 °C may enhance E. faecium growth, thereby increasing the potential for high tyramine production during Cheonggukjang fermentation.…”

Tyramine reduction by tyrosine decarboxylase inhibitor in Enterococcus faecium for tyramine controlled cheonggukjang

“…Tyramine is a biogenic amine (BA) produced in proteinrich fermented foods such as cheese, salami, dry sausages, and soybean pastes [1][2][3]. Adverse effects due to large amounts of tyramine ingestion through diet are known as 'cheese reaction'.…”

“…Tyrosine decarboxylase (TDC) activity has been produced by a variety of lactic acid bacteria (LAB), including several strains of Enterococci and Lactobacilli actively present during the manufacture of most fermented foods [7,8]. In most of previous studies, tyramine contents in Korean fermented soybean pastes such as cheonggukjang are up to 2000 mg/kg [3,9]. And other studies have reported that Enterococcus faecium was detected in cheonggukjang as tyramine high-producer [3,10].…”

The ability of Schisandra chinensis fruit to inhibit the growth of foodborne pathogenic bacteria and the viability and heat resistance of Bacillus cereus spores

“…Hence, it has been considered that lower pH reduces heat resistance of bacterial spores, which is in strong accordance with this observation. It is worth mentioning that, in addition to the antimicrobial and antisporal activity, S. chinensis has also been reported to reduce bacterial tyramine formation in a fermented soya food (Oh et al, 2012).…”