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

Young Kyoung Park,Bo Young Byun,Kwangcheol Casey Jeong,Junsu Lee,Jae-Hyung Mah,Young Hun Jin,Jun-Hee Lee

doi:10.3390/foods9070915

Young Kyoung Park, Bo Young Byun + Show 5 more

Open Access

https://doi.org/10.3390/foods9070915

Copy DOI

Abstract

The study evaluated the role of Enterococcus faecium in tyramine production and its response to fermentation temperature in a traditional Korean fermented soybean paste, Cheonggukjang. Tyramine content was detected in retail Cheonggukjang products at high concentrations exceeding the recommended limit up to a factor of 14. All retail Cheonggukjang products contained Enterococcus spp. at concentrations of at least 6 Log CFU/g. Upon isolation of Enterococcus strains, approximately 93% (157 strains) produced tyramine at over 100 µg/mL. The strains that produced the highest concentrations of tyramine (301.14–315.29 μg/mL) were identified as E. faecium through 16S rRNA sequencing. The results indicate that E. faecium is one of the major contributing factors to high tyramine content in Cheonggukjang. During fermentation, tyramine content in Cheonggukjang groups co-inoculated with E. faecium strains was highest at 45 °C, followed by 37 °C and 25 °C. The tyramine content of most Cheonggukjang groups continually increased as fermentation progressed, except groups fermented at 25 °C. At 45 °C, the tyramine content occasionally exceeded the recommended limit within 3 days of fermentation. The results suggest that lowering fermentation temperature and shortening duration may reduce the tyramine content of Cheonggukjang, thereby reducing the safety risks that may arise when consuming food with high tyramine concentrations.

Highlights

Cheonggukjang is a traditional Korean soybean paste produced by fermenting soybeans with
To investigate the influencing factors such as pH, salinity, and water activity on biogenic amines (BAs) content in Cheonggukjang, the physicochemical properties of Cheonggukjang samples were measured as described below
Retail Cheonggukjang half of the products fermentation temperature Of on the enterococcal growth and tyramine production

Summary

Introduction

Cheonggukjang is a traditional Korean soybean paste produced by fermenting soybeans withBacillus subtilis. Cheonggukjang is a traditional Korean soybean paste produced by fermenting soybeans with. Traditional methods of Cheonggukjang production utilize rice straw added to steamed soybeans for a short fermentation period of approximately 2–3 days, while starter cultures are used instead of rice straw for modern methods of production [1,2]. Fermentation of Cheonggukjang is a process involving microbial enzymatic proteolysis resulting in uniquely characteristic savory aromatic and flavor properties [3]. Despite the beneficial properties of Cheonggukjang, potentially hazardous biogenic amines (BAs) may be produced during fermentation of the proteinous food rich in precursor amino acids. The majority of BAs are formed through the reductive amination of ketones and aldehydes, as well as the decarboxylation of amino acids by microbially produced enzymes [6].

Methods

Results

Conclusion