Microbial communities related to sensory attributes in Korean fermented soy bean paste (doenjang).

ABSTRACT

Various microbial communities play a role in generating the distinctive sensory characteristics of the traditional Korean soybean paste, doenjang. The objective of this study was to investigate the relationship between sensory characteristics and microbial communities in traditional doenjang. The results of the descriptive analysis revealed that some traditional doenjang (T1-T11) exhibited distinctive characteristics, such as fish sauce flavor, meju, bitterness, sourness, and saltiness, whereas the modified samples (M1-M3) demonstrated sweetness, umami, and an alcohol odor. According to the metagenomic analysis based on 16S rRNA gene sequencing, the phylum Firmicutes was the dominant bacterium in most doenjang. At the genus level, lactic acid bacteria (LAB) were frequently found in most doenjang. Among these LAB, the major genera of bacteria were Tetragenococcus in M2 (60.30%), T3 (91.20%), T8 (48.60%), and T9 (60.90%); Enterococcus in T1 (29.40%), T4 (34.10%), and T10 (50.50%); Leuconostoc in T7 (89.10%); and Lactobacillus in T9 (38.3%). The most frequently occurring non-LAB was Bacillus in M3 (50.10%), T5 (46.50%), and T6 (20.50%), and M1 and T2 contained Staphylococcus and Ochrobactrum as their major non-LAB, respectively. The results of a correlation analysis between the sensory attributes from the descriptive analysis and the microbial communities from 454 pyrosequencing provided an overview for the relationship between sensory characteristics and microbial communities. Ochrobactrum, Stenotrophomonas, Rhodobacteraceae, Proteus, and Luteimonas were found in samples that had a strong fish sauce characteristic. The presence of LAB-Tetragenococcus, Enterococcus, Pediococcus, Carnobacterium, and Weissella-was related to sourness. Enterococcus and Enterobacter were found in samples with a matured flavor and a soft mouthfeel, respectively. The overall results of the study demonstrate that microbial communities found in doenjang were closely related to distinct sensory attributes.