• Microbiology and Biotechnology Letters
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• v.51 no.2
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• pp.147-156
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• 2023

Tetragenococcus halophilus CY54, an isolate from jeotgal, grows best in media with 5% NaCl and can grow at 18% and higher salt concentration. Three different doenjang samples were prepared with multiple starters including T. halophilus CY54. TBZA doenjang was prepared with T. halophilus, Bacillus subtilis, Zygosaccharomyces rouxii and Aspergillus oryzae. BZA doenjang was prepared with the same 3 starters except T. halophilus. KACC doenjang was prepared with a single starter, B. subtilis KACC16750. During 16 weeks of fermentation at 25℃, the viable counts were maintained in the range of 7-8 log CFU/g in all 3 samples. As fermentation progressed, pH decreased and titratable acidity (TA) gradually increased. Crude protein contents decreased slightly. TBZA doenjang showed higher amino-type nitrogen (ANN) and volatile basic nitrogen (VBN) contents, and KACC doenjang showed higher ammonia-type nitrogen (AMN) content. TBZA doenjang showed higher fibrinolytic and protease activity than other doenjang samples. Metabolites analyses by GC/MS showed that doenjang samples were separated from each other by partial least squares-discriminant analysis (PLS-DA) analysis. Seventeen major metabolites involved in the differences between samples were identified and they included organic acids, amino acids, sugars, fatty acids and alcohols. TBZA doenjang showed higher contents for most metabolites responsible for flavor and taste of fermented foods including doenjang. These results showed that T. halophilus could be useful as a starter for doenjang and can improve the product quality by accelerating the fermentation processes.

• Korean Journal of Food Science and Technology
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• v.42 no.3
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• pp.323-328
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• 2010

After supplemention with the licorice (Glycyrrhiza glabra), mustard (Brassica juncea), and chitosan as food additives to low-salted doenjang containing 30% lower salt than control doenjang (12.7% salt), fermentation properties of doenjang were investigated for 40 days. Adding the licorice, mustard, and chitosan to low-salted doenjangs containing 10.2% and 8.9% of salt did not affect the acidity, viable cell count, or color of doenjang. A white pellicle-forming strain was detected at the surface of low-salted doenjangs (10.2% and 8.9% salt) but not the control doenjang and low-salted doenjangs added with mixed additives (licorice, mustard, and chitosan). The amino nitrogen content of 8.9% salted doenjang added with mixed additives at 20 days was 332 mg% and this value was similar to that of 12.7% salted doenjang at 40 days. In sensory evaluation, the 8.9% salted doenjang added the additives had the highest score in overall palatability. These results indicate that salt contents of doenjang could be lowered to 8.9% by adding licorice, mustard, and chitosan, resulting in improved palatability, shortened fermentation period, and inhibited abnormal fermentation.

• Journal of Microbiology and Biotechnology
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• v.24 no.5
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• pp.648-660
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• 2014

Doenjang, a traditional Korean fermented soybean paste, is made by mixing and ripening meju with high salt brine (approximately 18%). Meju is a naturally fermented soybean block prepared by soaking, steaming, and molding soybean. To understand living bacterial community migration and the roles of bacteria in the manufacturing process of doenjang, the diversity of culturable bacteria in meju and doenjang was examined using media supplemented with NaCl, and some physiological activities of predominant isolates were determined. Bacilli were the major bacteria involved throughout the entire manufacturing process from meju to doenjang; some of these bacteria might be present as spores during the doenjang ripening process. Bacillus siamensis was the most populous species of the genus, and Bacillus licheniformis exhibited sufficient salt tolerance to maintain its growth during doenjang ripening. Enterococcus faecalis and Enterococcus faecium, the major lactic acid bacteria (LAB) identified in this study, did not continue to grow under high NaCl conditions in doenjang. Enterococci and certain species of coagulase-negative staphylococci (CNS) were the predominant acid-producing bacteria in meju fermentation, whereas Tetragenococcus halophilus and CNS were the major acid-producing bacteria in doenjang fermentation. We conclude that bacilli, LAB, and CNS may be the major bacterial groups involved in meju fermentation and that these bacterial communities undergo a shift toward salt-tolerant bacilli, CNS, and T. halophilus during the doenjang fermentation process.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.203-204
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• 2003

Change in Quality Properties of Doenjang Prepared with the Powder of Paecilomyces japonica and extract of P. japonica by different solvents were investigated during 90 days of fermentation at 20$^{\circ}C$. The moisture content was not significantly different, pH of Doenjang made with P. japonica was lower than control group and decreased continuously according to the fermentation time. Amino nitrogen continuously increased till 60 days and decreased slightly on 90 days. Value of L, a, b in Color decreased with proportion to fermentation period and L, a, b value of Doenjang made with P. japonica was lower and in Particular that of Doenjang made with P. japonica powder was lowest. From the result of sensory evaluation test, the color of control group was similar to “yellow”but that of Doenjang made with powder of P. japonica was close to“dark brown”and that of Doenjang made with extract of P. japonica was darker than that of control group and the preference of dark color was low. Texture was“glossy and smooth”in all and preference was high. In salty taste, Doenjang by P. japonica addition was stronger and Doenjang made with extract was stronger than that made with powder. Doenjang made with powder of P. japonica was weaker than other groups in sweet taste. In flavor and overall Preference, Doenjang made with P. japonica was scored lower slightly in than control group and Doenjang made with powder of P. japonica was the lowest in score.

• Food Science and Preservation
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• v.23 no.6
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• pp.788-796
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• 2016

This study presented the change of quality characteristics of Doenjang with various salt concentrations (4, 8, 15, and 20%) during 12 months. The pHs of Doenjang during fermentation were gradually increased for 12 months, whereas the pHs of Doenjang with 4 and 8% salt increased rapidly. Titratable acidity of Doenjang with 4 and 8% salt was high at initial time, while Doenjang with 15 and 20% salt was high at the 9 and 12 months. The amino-type nitrogen content of Doenjang with 4 and 8% salt was increased and ${\alpha}-amylase$ activity of all Doenjang was decreased during whole fermentation period. The protease activity of Doenjang with 4 and 8% salt was higher than Doenjang with 15 and 20% salt until 7 months. Total aerobic bacteria number 8.0~9.1 log CFU/g for 12 months, which was steady during fermentation period. Doenjang with 8% salt showed the highest score in umami taste whereas the lowest score in bitterness, astringency, and sourness tastes between 5 and 12 months. In conclusion, Doenjang with 8% salt was a suitable concentration for low-salt fermented foods.

• Food Science and Preservation
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• v.15 no.4
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• pp.518-523
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• 2008

This study sought to prepare Doenjang with added Ulmi cortex, to improve functionality and flavor, while retaining the original Doenjang scent. Ulmi cortex powders were added during fermentation. The Ulmi cortex-containing Doenjang showed lower pH and less salinity than did the Doenjang prepared without Ulmi cortex. Sensory evaluation data showed that Doenjang with Ulmi cortex tasted sweeter, and less salty, and was preferred over Doenjang without Ulmi cortex. In the DPPH assay, Doenjang with Ulmi cortex showed much higher free-radical scavenging ability (IC50 of 29.16 g/mL)did Doenjang without Ulmi cortex(IC50 of 155.67 g/mL), indicating that Ulmi cortex Doenjang has higher antioxidant levels. Doenjang prepared with 1%(w/v) Ulmi cortex powder was best in terms of consumer preference and functionality.

• Nutrition Research and Practice
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• v.9 no.6
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• pp.569-578
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• 2015

BACKGROUND/OBJECTIVES: Fermentation can increase functional compounds in fermented soybean products, thereby improving antioxidant and/or anti-inflammatory activities. We investigated the changes in the contents of phenolics and isoflavones, antioxidant activity and anti-inflammatory activity of Doenjang during fermentation and aging. MATERIALS/METHODS: Doenjang was made by inoculating Aspergillus oryzae and Bacillus licheniformis in soybeans, fermenting and aging for 1, 3, 6, 8, and 12 months (D1, D3, D6, D8, and D12). Doenjang was extracted using ethanol, and sequentially fractioned by hexane, dichloromethane (DM), ethylacetate (EA), n-butanol, and water. The contents of total phenolics, flavonoids and isoflavones, 2,2-diphenyl-1 picryl hydrazyl (DPPH) radical scavenging activity, and ferric reducing antioxidant power (FRAP) were measured. Anti-inflammatory effects in terms of nitric oxide (NO), prostaglandin (PG) E2 and pro-inflammatory cytokine production and inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 expressions were also measured using LPS-treated RAW 264.7 macrophages. RESULTS: Total phenolic and flavonoid contents showed a gradual increase during fermentation and 6 months of aging and were sustained thereafter. DPPH radical scavenging activity and FRAP were increased by fermentation. FRAP was further increased by aging, but DPPH radical scavenging activity was not. Total isoflavone and glycoside contents decreased during fermentation and the aging process, while aglycone content and its proportion increased up to 3 or 6 months of aging and then showed a slow decrease. DM and EA fractions of Doenjang showed much higher total phenolic and flavonoid contents, and DPPH radical scavenging activity than the others. At $100{\mu}g/mL$, DM and EA fractions of D12 showed strongly suppressed NO production to 55.6% and 52.5% of control, respectively, and PGE2 production to 25.0% and 28.3% of control with inhibition of iNOS or COX-2 protein expression in macrophages. CONCLUSIONS: Twelve month-aged Doenjang has potent antioxidant and anti-inflammatory activities with high levels of phenolics and isoflavone aglycones, and can be used as a beneficial food for human health.

• Journal of Microbiology and Biotechnology
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• v.24 no.10
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• pp.1397-1404
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• 2014

A few starters have been developed and used for doenjang fermentation but often without safety evaluation. Filamentous fungi were isolated from industrial doenjang koji, and their potential for mycotoxin production was evaluated. Two fungi were isolated; one was more dominantly present (90%). Both greenish (SNU-G) and whitish (SNU-W) fungi showed 97% and 95% internal transcribed spacer sequence identities to Aspergillus oryzae/flavus, respectively. However, the SmaI digestion pattern of their genomic DNA suggested that both belong to A. oryzae. Moreover, both fungi had morphological characteristics similar to that of A. oryzae. SNU-G and SNU-W did not form sclerotia, which is a typical characteristic of A. oryzae. Therefore, both fungi were identified to be A. oryzae. In aflatoxin gene cluster analysis, both fungi had norB-cypA genes similar to that of A. oryzae. Consistent with this, aflatoxins were not detected in SNU-G and SNU-W using ammonia vapor, TLC, and HPLC analyses. Both fungi seemed to have a whole cyclopiazonic acid (CPA) gene cluster based on PCR of the maoA, dmaT, and pks-nrps genes, which are key genes for CPA biosynthesis. However, CPA was not detected in TLC and HPLC analyses. Therefore, both fungi seem to be safe to use as doenjang koji starters and may be suitable fungal candidates for further development of starters for traditional doenjang fermentation.

• Food Science and Preservation
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• v.10 no.2
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• pp.213-218
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• 2003

In order to develop new functional doenjang, two types of medicinal herb doenjang were prepared with several medicinal herbs, bamboo salts and meju and then changes of its physiological functionalities were investigated during 6 months of fermentation. Antihypertensive angiotensin converting enzyme(ACE) inhibitory activities of medicinal herb doenjangs were decreased to 39.0∼5l.7% from 61.7∼72.5% after 6 months of fermentation. Fibrinolytic activity and electron donating ability of medicinal herb doenjangs were showed 10.4∼11.3 U and 96.3∼99.1% after 6 months of fermentation, respectively. SOD-like activity of medicinal herb doenjangs were also showed approximate 10% and tyrosinase inhibitory activity of 20$^{\circ}C$ -water extracts of medicinal herb doenjang(I) was increased up to 97.6% from 12.9% after 6 months of fermentation. Crude protein content and total sugar content of medicinal herb doenjangs were approximate 14% and 33%, respectively, which were higher than those of traditional doenjang.

• Food Science and Preservation
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• v.15 no.1
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• pp.139-143
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• 2008

The potential use of Doenjang in place of salted-fish juice as an ingredient in Kimchi fermentation was examined, to improve Kimchi qualities such as flavor and taste. Quality characteristics were monitored during progressive fermentation of Kimchi with Doenjang (KD) at 7 d intervals for 28d at constant temperature $(10^{\circ}C)$. The data showed that the pH of KD was somewhat lower than that of the control as fermentation progressed. The titratable acidity in KD was linearly proportional to the pH change. Both the growth of lactic acid bacilli and total bacteria in Kimchi were inhibited in KD compared to control. In terms of color, the L, a, and b values of KD were all lower than those of control. In sensory evaluation, the taste, flavor, color, and overall acceptability of the new form of Kimchi were increased significantly by addition of 5 % (w/w) Doenjang (p<0.05). All data indicated that the color and taste properties of KD were improved by addition of Doenjang during fermentation.