Changes in microbial communities and their correlation with physicochemical properties during the fermentation of doenjang

Despite extensive research on doenjang fermentation, studies exploring the correlation between microbial dynamics and its quality attributes remain limited. This study was conducted to elucidate the relationship between microbial changes and physicochemical characteristics during the fermentation process of doenjang. During the fermentation period of doenjang, from day 0 to day 90, significant decreases were observed in moisture, pH, salinity, and monosaccharide levels such as glucose and fructose, while the contents of amino-type nitrogen (AN) and lactic acid increased. Analysis of microbial changes during the fermentation period of doenjang revealed that the proportions of Bacillus and Tetragenococcus increased as fermentation progressed, whereas the proportions of lactic acid bacteria, such as Enterococcus, Pediococcus, and Leuconostoc, decreased. Bacillus and Tetragenococcus exhibited similar correlation patterns with other variables. The microbial proportions of Bacillus and Tetragenococcus were positively correlated with AN and lactic acid content but negatively correlated with moisture, pH, salinity, and glucose content in doenjang. In contrast, the proportions of lactic acid bacteria such as Enterococcus, Pediococcus and Leuconostoc were negatively correlated with AN and lactic acid content, while showing positive correlations with moisture content, pH, salinity, and glucose content. These findings indicate a close correlation between microbial communities and quality characteristics during the fermentation of doenjang.