Comparison of the quality characteristics and microbial community of traditional doenjang across fermentation places

Abstract

We investigated the quality characteristics and microbial community found in traditional outdoor-type doenjang fermented at different temperatures. The quality characteristics that were highly correlated with fermentation temperature were analyzed. The average temperature of doenjang in the summer was highest in the order of fermentation by field in Damyang (JDF), fermentation by smart management facility in Damyang (JDS), and fermentation by field in Pyeongchang (JDFP), and in winter was the highest in the order JDS, JDF, and JDFP. The b* value and the degree of browning were highest in the order of JDF, JDS, and JDFP. Among the quality characteristics that affect the degree of fermentation and taste, samples with high summer temperature showed high ammonia nitrogen content, α-amylase activity, sugar content, organic acid content, and acidity and samples with high winter temperature showed high protease activity, amino nitrogen content, biogenic amine content, and alcohol content. Regarding the microbial community, the level of the Enterococcus genus was high in the samples with low winter temperatures, while the level of the Bacillus genus was high in the samples with high winter temperatures. Additionally, the genus Wickerhamiella and Zygosaccharomyces were highest in the samples with the lowest temperatures in summer and winter. Furthermore, acidity, biogenic amine content, glucose content, and lactic acid content were analyzed as major factors influencing the quality characteristics of doenjang according to the ripening region and location.