Addition of Coriander during Fermentation of Korean Soy Sauce (Gangjang) Causes Significant Shift in Microbial Composition and Reduction in Biogenic Amine Levels

The microflora of Korean soy sauce (gangjang) play an important role in maintaining its quality and safety. Hence, it is important to study the microflora and the possible approaches to improve their composition. In this study, the effect of adding coriander during soy sauce fermentation on the microflora and biogenic amines was evaluated using metagenomics and H-1 NMR analyses, respectively. The beta-diversity showed a clear distinction between the microbiota of the coriander and control groups. Microbial composition analysis revealed noticeable shifts, as Firmicutes abundance was significantly higher in the coriander group (91.77%) than that in the control (38.78%). The dominant bacterial family in the coriander group was the Bacillaceae (57.94%), while Halomonadaceae was dominant in the control group (49.77%). At the species level, Chromohalobacter beijerinckii dominated the microbial community in the control group (49.54%), but not (4.43%) in the coriander group. Moreover, there was a negative correlation between the Bacillaceae and several other bacterial families, including Halomonadaceae, which indicated a possible antagonism and partly explained the reduction in Chromohalobacter abundance in the coriander group. The levels of the biogenic amines histamine, putrescine, and tyramine, which are considered potential health risk factors, were significantly lower in the coriander soy sauce than those in the control sauce. The results of this study suggest that the addition of coriander during Korean soy sauce fermentation is beneficial, as coriander significantly reduces the levels of biogenic amines and the bacteria that produce them.