Korean Soybean Paste Research Articles

Media Optimization for Bacteriocin Production by Enterococcus faecium Strains Isolated from Traditional Korean Soybean Paste

Media Optimization for Bacteriocin Production by Enterococcus faecium Strains Isolated from Traditional Korean Soybean Paste

Complete genome sequence of Arthrobacter sp. KFRI-F3372, a strain isolated from Korean soybean paste Doenjang.

Arthrobacter sp. KFRI-F3372 is a Gram-positive bacterium with a high G + C content of 65.7%, which was isolated from Doenjang, a traditional Korean fermented soybean paste. In this report, we introduce the complete genome sequence of Arthrobacter sp. KFRI-F3372.

Isolation and Characterization of Enterococcus faecium from Fermented Korean Soybean Paste with Antibacterial Effects

In the present study, a total of eight Enterococcus faecium (OQ940301, OQ940302, OQ940303, OQ940304, OQ940305, OQ940308, OQ940309, and OQ940310) were isolated from soybean paste, a traditional Korean fermented food, and evaluated for their probiotic properties. The results showed that all the E. faecium strains survived in simulated human gastrointestinal conditions (4.1–5.59 log10 CFU/mL). In addition, the range of auto-aggregation was 5–25%, the hydrophobicity was around 94%, and it exhibited significant co-aggregation ability with Salmonella enterica and Staphylococcus aureus. However, all the isolates were shown to be resistant to Gentamycin. The bacterial cell-free supernatant showed antibacterial activity against S. enterica, Escherichia coli, Bacillus cereus, Listeria monocytogenes, and S. aureus. Furthermore, E. faecium exhibited potent anti-oxidant activity by scavenging 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) free radicals. In addition, safety was confirmed by evaluating the hemolytic activity in blood agar; none of the bacterial isolates showed hemolysis. These results demonstrated that E. faecium (OQ940301 and OQ940309) isolated from soybean paste showed a higher probiotic potential.

Complete Genome Sequence of Bacillus sp. Strain KICET-1, Isolated from Soybean Paste (Doenjang).

Bacillus sp. strain KICET-1, a bacterium isolated from traditional Korean soybean paste (Doenjang) at Osong, has one 4,099,652-bp DNA chromosome. The G+C content is 46.1%, and KICET-1 shares 99.64% similarity with Bacillus velezensis CR-502T (AY603658), according to phylogenetic classification based on 16S rRNA gene sequences.

Effect of the Types of Starter on Microbiological and Physicochemical Properties of Dry-Cured Ham.

This study analyzed the microbiological (Lactobacillus spp., Staphylococcus spp., mold, yeast, aerobic bacteria) and physicochemical properties [pH, salinity, water activity, volatile basic nitrogen (VBN), and thiobarbituric acid reactive substances]. The starters were used by mixing Debaryomyces hansenii separated from Korean Doenjang (D) and fermented sausage (S). The starter was inoculated with dry-cured ham and aged for 6 weeks at 20°C and 25°C, respectively. The aerobic bacteria, Lactobacillus spp., and Staphylococcus spp. of D, S, and DS treatment showed significantly higher values at 25°C than at 20°C. Among them, S25 treatment showed a high tendency. At week 6, the mold of the S25 treatment was significantly higher than the S20 treatment, and the yeast was higher in 25°C than 20°C (p<0.05). The pH of all treatment groups increased with the aging period. Compared with that at 25°C, the pH was significantly higher at 20°C (p<0.05). The water activity showed a significant decrease as the aging period increased, and the treatment of D25, S20, and DS20 showed a significantly higher value at week 6 (p<0.05). Compared with that at 20°C, the VBN content was higher at 25°C. At week 6, the VBN contents of the C20, S25, and DS25 groups were higher than those of the other treatment groups. Therefore, inoculation of D. hansenii separated from fermented sausage produced in Korean starter at 25°C is expected to improve the safety of harmful microorganisms and physiochemical properties in dry-cured ham.

감태 분말 첨가 된장의 품질 특성

Doenjang (Korean soybean paste) was prepared by adding of Ecklonia cava powder (w/w 0.3.6,9%) to Meju fermented for 30℃ for 40 days. The pH level of all samples did not show any significant decrease or increase by days 20 and 30, but the pH level increased near the end of the fermentation process by day 40 compared to the early days of fermentation, with the highest pH for the control group with no added powder and the lowest for the 9% group. The titratable acidity in the 9% group was measured to be the highest, as all the samples increased from the initial fermentation on the 40th day of fermentation. At the start of fermentation, the control group showed the lowest levels of total nitrogen and amino acid content and the 9% group showed the highest. However, by day 40 of fermentation, the control group showed the highest levels and the 9% group showed the lowest levels. The nitrogen degradation rate (NDR) was increased as the fermentation process continued, the control group showed the highest levels by day 40, but the 9% group showed the lowest levels of NDR, showing a decreasing trend as more powder is added. As the fermentation process continued, the levels of reducing sugar decreased, with the control group showing the lowest level and the 9% group with the highest level. The total number of bacteria was significantly reduced from 7.12 to 8.28 log CFU/g at the beginning of fermentation to 6.00 to 6.15 log CFU/g by day 40 of fermentation. The total polyphenol content and % DPPH radical scavenging activity increased significantly with the addition of Ecklonia cava powder in both the early fermentation and the last day of fermentation, showing a higher polyphenol content on the last day of fermentation compared to the first day. In a survey of consumer preferences was showed that the control group with no addition of Ecklonia cava powder showed the highest values in appearance and aroma. However, although there were no significant differences in taste-related assessments (salty taste, umami, after taste) and overall acceptability, the preference for the group with 6% Ecklonia cava powder was the highest. Based on these findings, it was confirmed that soybean paste with 6% of Ecklonia cava powder had the best effect on the preference and functionality of soybean paste, and the possibility of manufacturing soybean paste using Ecklonia cava powder has potential in food development.

High-throughput sequencing of the microbial community associated with the physicochemical properties of meju (dried fermented soybean) and doenjang (traditional Korean fermented soybean paste)

Doenjang, a traditional Korean soybean paste consisting of fermented meju has been consumed for centuries as a protein source. In this study, the physicochemical factors and microbial communities of samples prepared from four batches of meju and doenjang were investigated to identify the factors that affect the food quality. The water content and salt concentration were higher in doenjang than in meju, and the acidity and amino-type nitrogen varied depending on the batch. After fermentation of doenjang, the pH, salt concentration, and amino-type nitrogen increased in all batches. Enterococcus and Bacillus were present in all meju samples, whereas Enterococcus, Tetragenococcus, and Bacillus were present in all doenjang samples. The dominant fungi in meju and doenjang was Aspergillus. The abundance of certain fungi, such as Debaryomyces, Candida, Mucor, and Gibberella, varied batch to batch. The amino-type nitrogen, which determines the quality of doenjang, was correlated with the relative abundance of Aspergillus in doenjang prior to fermentation. In addition, these strains had a negative correlation with the salt concentration. This study has elucidated the composition of microbial communities in meju and doenjang, which may lead to improved quality in the production of fermented food.

Questionnaire Survey of the Methods Used in Household Doenjang Production in Korea

This study examined the methods used in household doenjang (Korean soybean paste) production. Nine hundred fortythree responses were obtained using a nationwide, questionnaire-based survey (2018-2019) with non-probabilistic snowballing sampling. Consistent with previous studies, the respondents were primarily over the age of 50 years (97.1%) and female (97.9%). In addition to soybeans, the most used ingredients were red pepper (85.8%) and charcoal (85.5%), which most respondents obtained through direct farming (50.4-59.9%). Seasonal production occurred later in the higher latitude regions (Gyeonggi-do, Gangwon-do, Chungcheong-do) (p < 0.01), which have lower average temperatures, and the fermentation period was shorter in the lower latitude regions (Jeolla-do, Gyeongsang-do, Jeju-do) (p < 0.01), which have higher average temperatures. There were no significant regional differences in the season when doenjang was made, with most production occurring during January and February (81.1%). Most respondents (71.3%) made doenjang using homemade meju (soybean block used as a starter) in a traditional way to allow the microorganisms to be naturally inoculated. These results could be used as a basis for future research on topics such as starter development, standardized production, and safety of household doenjang.

Effects of Doenjang, a Traditional Korean Soybean Paste, with High-Salt Diet on Blood Pressure in Sprague-Dawley Rats.

Fermented foods in Korea contain a lot of salt. Although salt is reported to exacerbate health trouble, fermented foods have beneficial effects. We hypothesized that doenjang could reduce blood pressure in Sprague–Dawley (SD) rats fed a high-salt diet. Eighteen SD rats were divided into three groups: normal-salt (NS) group, high-salt (HS) group, and high-salt with doenjang (HSD) group. The salinity of doenjang and saltwater was adjusted to 8% using Mohr’s method. Blood pressure was significantly reduced in the HSD group compared with the HS group. Water intake and urine excretion volume has significantly increased in the HS group compared with the HSD group. The excreted concentrations of urine sodium, urine potassium, and feces potassium significantly increased in the HSD group compared with the HS and NS groups. Renin level was significantly decreased in the HSD group compared to the other groups. These results indicate that eating traditional salty fermented food is not a direct cause of hypertension, and the intake of doenjang in normal healthy animals improved blood pressure.

Simultaneous Determination of Twenty Mycotoxins in the Korean Soybean Paste Doenjang by LC-MS/MS with Immunoaffinity Cleanup.

Doenjang, a Korean fermented soybean paste, is vulnerable to contamination by mycotoxins because it is directly exposed to environmental microbiota during fermentation. A method that simultaneously determines 20 mycotoxins in doenjang, including aflatoxins (AFs), ochratoxin A (OTA), zearalenone (ZEN), and fumonisins (FBs) with an immunoaffinity column cleanup was optimized and validated in doenjang using LC-MS/MS. The method showed good performance in the analysis of 20 mycotoxins in doenjang with good linearity (R2 > 0.999), intra- and inter-day precision (<16%), recovery (72–112%), matrix effect (87–104%), and measurement uncertainty (<42%). The validated method was applied to investigate mycotoxin contamination levels in commercial and homemade doenjang. The mycotoxins that frequently contaminated doenjang were AFs, OTA, ZEN, and FBs and the average contamination level and number of co-occurring mycotoxins in homemade doenjang were higher than those in commercially produced doenjang.

Toxicological evaluation of lotus, ginkgo, and garlic tailored fermented Korean soybean paste (Doenjang) for biogenic amines, aflatoxins, and microbial hazards

The present study aimed to develop a consortium of nutritive fermented food products, supplemented with phytochemicals, with reduced toxicological contents. We developed new flavored Doenjang products (protein rich) fermented with lotus, ginkgo, and garlic plant extract-based Meju (termed as EMD) as the starter culture and by using traditional Meju (termed as TMD), where these plant extracts were added later during the fermentation process. Fermented Doenjang samples were analyzed for reduced levels of biogenic amines (BAs), aflatoxins, and microbial hazards, (including Bacillus cereus) as well as for their nutritive contents and antioxidant potential, after varying periods of fermentation (0, 3, 6, 9 and 12 months). All Doenjang samples prepared using plant extracts and their mixtures (1% and 10%) showed desired reduction in B. cereus counts, BAs, aflatoxins, and other foodborne pathogens as well as showed potent antioxidant abilities, including phenolic/flavonoid contents. Based on the higher efficiency in reducing various toxicants, Ginkgo biloba leaf extract added TMD samples were selected for the development of Doenjang products as an innovative approach, with great potential to improve the quality and safety of soybean fermented products in the Korean market, offering enhanced health benefits and reduced risks of toxicity.

Purification and characterization of thermostable l-asparaginase from Bacillus amyloliquefaciens MKSE in Korean soybean paste

This study aimed to produce and characterize thermostable l-asparaginase from Bacillus amyloliquefaciens MKSE, a newly screened strain from Korean fermented soybean paste. The isolated MKSE was identified by its morphological, biochemical, and physiological properties and 16S rRNA sequence. Its l-asparaginase II-like gene was expressed in Escherichia coli BL21 (DE3), by using the pET-28a (+) vector. The produced l-asparaginase (specific activity of 4.75 IU/mg) was purified by a one-step procedure, using nickel-affinity chromatography, and its molecular weight of 38.2 kDa was determined by gel electrophoresis. Its optimum pH and temperature were 8.5 and 65 °C, respectively. The enzyme was highly stable in the pH range of 3.0–11.0 for 6 h incubation, and the enzyme retained about 57% of its activity at 95 °C for 6 h. Its activity was activated in the presence of Mn2+, Mg2+, and Fe2+ while it was inhibited by Zn2+, Cu2+, PMSF, and SDS. Its Km was 1.5 mM, and its Vmax was 136.3 IU/mg. The results of this study reveal that MKSE l-asparaginase has a great potential to be used in various industries, due to its stability at high temperature and over a wide pH range.

Analysis of Iodine Content in Salts and Korean Sauces for Low-Iodine Diet Education in Korean Patients with Thyroid Cancer Preparing for Radioiodine Therapy.

A low-iodine diet is necessary in patients about to undergo radioiodine therapy for thyroid cancer to decrease the competitive absorption of ingested nonradioactive iodine. This study aimed to assess the iodine concentrations in salts and basic Korean sauces, and to provide fundamental data for guidelines on a low-iodine diet before radioiodine therapy. The iodine contents of refined salts, solar sea salts, fish sauces, and commonly used Korean sauces with added refined salt were determined by ICP-MS. The iodine content of refined salts was found to be very low (0.033±0.05μg/100g) compared with that of solar sea salts (434±73.6μg/100g). The iodine contents of Korean soy sauce, Korean soybean paste, Gochujang seasoned with refined salt were also very low (0.010, 0.044, 0.002μg/100g, respectively). However, the mean iodine contents of the shrimp and fish Jeots analyzed in this study were found to be 41.3 ± 4.2 and 24.8 ± 4.5μg/100g, respectively. This study is the first to investigate the iodine contents of the salts and basic sauces used in Korea. The results show that refined salts and Korean traditional sauces seasoned with them can be safely used in low-iodine diets before radioiodine therapy.

Acceleration of Aglycone Isoflavone and γ-Aminobutyric Acid Production from Doenjang Using Whole-Cell Biocatalysis Accompanied by Protease Treatment.

Recently, soybean isoflavone aglycones (i.e., daidzein and genistein) and γ-aminobutyric acid (GABA) have begun to receive considerable consumer attention owing to their potential as nutraceuticals. To produce these ingredients, multiple microorganisms and their enzymes are commonly used for catalysis in the nutraceutical industry. In this work, we introduce a novel fermentation process that uses whole-cell biocatalysis to accelerate GABA and isoflavone aglycone production in doenjang (a traditional Korean soybean paste). Microbial enzymes transform soybean isoflavone glycosides (i.e., daidzin and genistin) and monosodium glutamate into soybean isoflavone aglycones and GABA. Lactobacillus brevis GABA 100 and Aspergillus oryzae KACC 40250 significantly reduced the production time with the aid of a protease. The resulting levels of GABA and daidzein were higher, and genistein production resembled the levels in traditional doenjang fermented for over a year. Concentrations of GABA, daidzein, and genistein were measured as 7,162, 60, and 59 μg/g, respectively on the seventh day of fermentation. Our results demonstrate that the administration of whole-cell L. brevis GABA 100 and A. oryzae KACC 40250 paired with a protease treatment is an effective method to accelerate GABA, daidzein, and genistein production in doenjang.

朝鲜族传统大酱抗疲劳作用的研究

试验研究了朝鲜族传统大酱的抗疲劳作用。将40只体重为18~22 g的雄性清洁级昆明种小鼠随机分为4组，即空白对照组，朝鲜族大酱低、中、高三个剂量组(0.2 g/kg/d、0.4 g/kg/d、0.8 g/kg/d)，每3 d称量一次小鼠体重，连续灌胃4周。4周后，对各组小鼠爬杆时间、负重游泳时间以及游泳后肝糖原和肌糖原含量进行测定，比较各组小鼠脏器系数及体重的变化。结果显示经口给予小鼠不同剂量的大酱4周后，大酱高、中、低剂量组小鼠爬杆时间和负重游泳时间均极显著长于空白对照组(P 0.05，并无显著性差异。由此证明了朝鲜族大酱具有一定的抗疲劳作用。 The research mainly studied the anti-fatigue effect of the Korean soybean paste. 40 male Kunming mice weighing 18 - 22 g were taken and randomly divided into the control group, the low dose, middle dose and high dose group (0.2 g/kg/d, 0.4 g/kg/d, 0.8 g/kg/d). The weight of mice in each group was measured every three days and the three dose paste samples were gavaged for 4 weeks. At the end of the experiment, the pole-climbing time and load-swimming time were measured, and hepatic glycogen content and muscle glycogen content after swimming were also measured. Organ coefficient in each group of mice and body weight in each group was analyzed. Results showed that after 4 weeks’ gavage with different dose of Korean soybean paste, the pole-climbing and load-swimming time was significantly prolonged compared with the control group (P 0.05). Thus the anti-fatigue effect of Korean soybean paste is proved.

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

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.

연령에 따른 여성들의 된장에 대한 인식과 이용실태 : 대구지역 중심으로

연령에 따른 여성들의 된장에 대한 인식과 이용실태 : 대구지역 중심으로

Bacterial Identification and Detection of Equol in Korean Soybean Paste

Bacterial Identification and Detection of Equol in Korean Soybean Paste

Lactobacillus plantarum-mediated conversion of flavonoid glycosides into flavonols, quercetin, and kaempferol in Cudrania tricuspidata leaves

High value-added food materials were developed based on enhancement of phenolic contents in Cudrania tricuspidata leaves using fermentation of silkworm thorn leaves with Lactobacillus derived from Korean soybean paste. Ethanol extracts from fermentates were examined for antioxidant activities and flavonoid and corresponding glycoside contents. Radical scavenging activities were increased by approximately 20% after fermentation. Two prominent spectral peaks in fermentates that increased in size, compared with non-fermentates, were identified as quercetin (m/z 301.1) and kaempferol (m/z 285.3). Three peaks that decreased in size in fermentates were identified as quercetin-7-O-beta-glucopyranoside (m/z 463.1), kaempferol-3-O-beta-glucopyranoside (m/z 447.1), and kaempferol-7-O-beta-glucopyranoside (m/z 447.2). Conversion of flavonoid glycosides to flavonols, quercetin and kaempferol, occurred in silkworm thorn leaves due to fermentation with Lactobacillus.

Doenjang, a Korean soybean paste, ameliorates TNBS-induced colitis in mice by suppressing gut microbial lipopolysaccharide production and NF-κB activation

In preliminary studies, 80% ethanol extract of doenjang, a traditional Korean soybean paste, showed anti-inflammatory effect in lipopolysaccharide (LPS)-stimulated macrophages. Therefore, we investigated the effect of doenjang on 2,3,4-trinitrobenzene sulphonic acid (TNBS)-induced colitis in mice. Doenjang extract potently inhibited NF-κB activation in LPS-stimulated peritoneal macrophages. Oral administration of doenjang significantly inhibited TNBS-induced colon shortening, myeloperoxidase activity, body weight loss, and NF-κB activation in mice. Doenjang reversed the TNBS-caused suppression of tight junction proteins. Doenjang also inhibited TNBS-induced expression of inducible nitric oxide synthase, cyclooxygenase-2, TNF-α, IL-1β, and IL-6, and activation of NF-κB, but increased IL-10 expression. Doenjang significantly increased the number of Bifidobacteria in TNBS-induced colitic mice, but reduced the number of Erypsipelotrichaceae. Furthermore, doenjang suppressed TNBS-induced gut microbial LPS production. Doenjang also restored TNBS-disturbed gut microbiota, determined by principal coordinates analysis. These results indicate that Doenjang may ameliorate colitis by restoring disturbed gut microbiota and inhibiting NF-κB signaling pathway.