• Food Science and Preservation
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• v.22 no.3
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• pp.458-463
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• 2015

Many Koreans, who are resident in Uzbekistan and Central Asia, are still avid fans of the Korean traditional soybean paste. No research study has been conducted on the Korean-Uzbekistanis soybean paste. The purpose of this study was to investigate the quality characteristics of the Korean-Uzbekistanis fermented soybean paste. Nine kinds of soybean pastes prepared by Korean-Uzbekistanis were collected, and their physiochemical properties (protease activity, amylase activity, amino type nitrogen content, reducing-sugar contents, and aerobic bacterial count) have been analyzed. The Korean-Uzbekistanis' fermented soybean paste (KU-SP) showed higher protease activity than the Korean fermented soybean paste (K-SP). The protease activities of KU-SP B, D, and H were 832, 807 and 630 unit/g, respectively, which were significantly different from others. In addition, the content of amino-type nitrogen in KU-SP B, D, and H were 777 mg%, 686 mg%, and 705 mg%, respectively. In the meanwhile, ${\alpha}$-amylase activities showed wide ranges starting from 10.82 to 47.98 unit/g. The KU-SP values, except for the KU-SP C, have shown higher activities than the K-SP. The reduced sugar content and totoal aerobic bacteria number were within the range of 0.55~3.43%/g and 7.24~8.79 log CFU/g, respectively. Finally, this research provided the basic data and information for the quality characteristics of commercial soybean paste prepared by the Korean-Uzbekistanis. These basic data can be useful for understanding the Korean food culture in Central Asia.

• Korean Journal of Microbiology
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• v.55 no.2
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• pp.131-142
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• 2019

The primary objective of this study was to determine the content of biogenic amines in Korean traditional fermented soybean pastes (doenjang) and to isolate potential probiotic Bacillus sp. with the ability to inhibit biogenic amines accumulation. There were significant differences in the bacterial cell counts, pH value, titratable acidity, salinity, and biogenic amine content between the samples. Among Bacillus strains isolated from doenjang, Bacillus (B.) licheniformis DB102, B. subtilis DB203, B. stearothermophilus DB206, Bacillus sp. DB209, Bacillus sp. DB310, B. coagulans DB311, B. cereus DB313, B. amyloliquefaciens DB714, Bacillus sp. DB917, B. cereus DB 915, B. subtilis DB1020, and Bacillus sp. DB1022 were found to be able to produce biogenic amines. On the other hand, biogenic amine-degrading strains were identified as Bacillus sp. DB403, Bacillus sp. DB407, B. subtilis DB517, B. licheniformis DB612, and B. subtilis DB821. In particular, Bacillus sp. DB407 and B. subtilis DB821 showed probiotic properties including tolerance to artificial digestive juices, adherence to intestinal epithelial cells, resistance to antibiotics, and antibacterial activity against biogenic amine-producing strains. In conclusion, the two probiotic Bacillus strains may be considered as the suitable starter for manufacture of fermented soybean foods with low biogenic amines content.

• Korean Journal of Food Science and Technology
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• v.40 no.4
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• pp.406-411
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• 2008

This study was conducted to examine the quality enhancement of fermented soybean pastes (cheonggukjang) using microorganisms with high enzyme activities and proper experimental design. The microorganisms for soybean paste fermentation were selected from a specific area of Gyeonggi and were idenlified by 16S rDNA sequence analysis. To prepare the cheonggukjang, an optimum mixing ratio of selected microorganisms was determined using contour plots and numerical optimization methods. A total of 39 microorganisms were isolated from the soybean paste, consisting primarily of Bacillus subtilis and Bacillus licheniformis, and no mold was found. Three microorganisms showing high enzyme activities were selected and used to formulate an optimum mixing ratio for cheonggukjang preparation. Based on levels of amino-nitrogen, ammonium-nitrogen, antioxidant activity values, and sensory preference results, the optimum mixing ratio of 50% of Bacillus sp. SC-1 and 50% SC-3 was suggested for the manufacture of high quality of cheonggukjang.

• Korean Journal of Food Science and Technology
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• v.38 no.6
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• pp.730-737
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• 2006

High performance liquid chromatographic methods for the simultaneous determination of 12 biogenic amines were developed and contents of biogenic amines in 23 varieties of Korean commercial fermented food were analyzed. Dansyl derivatives of biogenic amine were very stable and had good peak resolution. Except agmatine, the recovery of biogenic amines from soybean paste with extraction of 0.1 N HC1 added biogenic amines to soybean paste was greater 85%. The calibration curve showed good linearity over a concentration range up to 50 ${\mu}g/mL$. In the determination of biogenic amine level in Korean commercial fermented foods, doenjang and chungkukjang (fermented soybean pastes), soy sauce, anchovy and pacific sand lance liquid jeotkal (fermented fish sauce products), and cabbage kimchi had high level biogenic amines. Especially, traditional doenjang had a histamine (HIS) level of 952.0 mg/kg, a tyramine (TYR) level of 1,430.7 mg/kg. Most cheese had low level of biogenic amines, but one Gouda cheese had a tyramine (TYR) level of 97.5 mg/kg. A low level of biogenic amines was detected in wines, beer, yoghurt, and sausage. Putrescine (PUT), cadaverine (CAD), tryptamine (TRY), histamine (HIS), tyramine (TYR), and 2-phenylethylamine (PHE) were mainly formed in fermented foods by the action of microorganism, so their levels were high with a range. On the other hand, spermidine (SPD), spermine(SPM), serotonin (SER), noradrenaline (NOR), and dopamine (DOP) were formed originally via biosynthesis with consequent low level.

• Microbiology and Biotechnology Letters
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• v.42 no.2
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• pp.99-105
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• 2014

A Bacillus strain capable of hydrolyzing locust bean gum was isolated as a producer of extracellular mannanase by way of an enrichment culture in an acidic medium from homemade soybean pastes. The isolate YB-1401 showed a biochemical identity of 61.1% with Brevibacillus laterosporus, while the nucleotide sequence of its 16S rDNA had the highest similarity with that of Bacillus amyloliquefaciens. The mannanase productivity of the Bacillus sp. YB-1401 was drastically increased by mannans. Particularly, maximum mannanase productivity was reached at approximately 265 U/ml in LB medium supplemented with konjac glucomannan (4.0%). The mannanase was the most active at $55^{\circ}C$ and pH 5.5. Mannanase activity was completely maintained after pre-incubation at pH 3.5 to 11.0 for 1 h. The predominant products resulting from the mannanase hydrolysis were mannobiose and mannotriose for LBG, guar gum or mannooligosaccharides. A small amount of mannose was also detected in the hydrolyzates.

• Korean Journal of Food Science and Technology
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• v.50 no.2
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• pp.152-164
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• 2018

Fermented seasoning pastes were prepared by Aspergillus oryzae and Bacillus subtilis using three edible insects, Tenebrio molitor larvae (TMP), Gryllus bimaculatus (GBP), and Bombyx mori pupa (SPP), with soybean (SBP) as a negative control. Volatile compounds were extracted by the headspace solid-phase microextraction (HS-SPME) method and confirmed by gas chromatograph-mass spectrometry (GC-MS). In total, 121 volatiles from four samples were identified and sub-grouped as 11 esters, 18 alcohols, 23 aldehydes, 5 acids, 10 pyrazines, 2 pyridines, 7 aromatic hydrocarbons, 10 ketones, 19 alkanes, 9 amides, 4 furans and 3 miscellaneous. TMP, GBP, SPP and SBP had 48, 54, 36, and 55 volatile compounds, respectively. Overall, 2,6-dimethylpyrazine and trimethylpyrazine were found by a high proportion in all samples. Tetramethylpyrazine, a main flavor of doenjang, a Korean fermented seasoning soybean paste, was identified as one of the major compounds in TMP, SPP, and SBP. SBP had benzaldehyde, hexanal, n-pentanal, and aldehydes and SPP with pyrazines.

• Food Engineering Progress
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• v.14 no.2
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• pp.153-158
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• 2010

Changes in physicochemical properties of soybean pastes (Doenjang) of various salt contents (8-14%) during fermentation were investigated to explore the possibility of manufacturing a low salt soybean paste. Titratable acidity (TA) increased and consequently pH decreased with the fermentation time. The rates of TA and pH changes increased as the salt levels decreased. Protein contents remained unchanged and there were no differences among different salt levels. The amino nitrogen contents and the volatile basic nitrogen contents increased with fermentation time and showed higher values at lower salt levels. The reducing sugar contents increased from 6th to 11th week of fermentation, and decreased afterward. No remarkable differences in the reducing sugar contents were observed with respect to salt levels. Shorter fermentation periods were required at reduced salt levels. Appropriate fermentation periods of the 8, 10, 12 and 14% salt containing Doenjang were 2 to 11 weeks, 3 to 12 weeks, 6 to 14 weeks, and 9 to 15 weeks, respectively. Doenjang fermented for shorter period of time at lower salt content showed better sensory quality than that for longer period at higher salt content.

• The Korean Journal of Food And Nutrition
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• v.34 no.1
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• pp.58-68
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• 2021

This study investigated the microbial community and quality characteristics of traditional soybean pastes (doenjang) based on the aging period in Gyeongnam province. The samples were collected from seven regions in Gyeongnam Province (Goseong, Hadong, Haman, Hamyang, Sacheon, Sancheong and Uiryeong). Contents of moisture, salinity, pH, and acidity of doenjang after 210 days aging were 56.40~65.21%, 9.05~16.08%, 4.88~6.86 and 0.64~2.14%, respectively. Lightness significantly decreased over the aging period, while the redness tended to increase over the aging period. Yellowness was from 21.39~26.81 to 21.10~28.36. Reducing sugar content was from 0.31~1.45% to 0.11~3.13%. The amino-type content increased from 141.87~495.13 mg/100 g to 328.53~823.67 mg/100 g. In contrast, the ammonia-type content declined from 136.74~364.70 mg/ 100 g to 128.62~331.00 mg/100 g. The overall total microbial count did not significantly differ, but it tended to decrease in sample GD4. Fungus declined overall or was not detected. Coliform groups were not detected in all samples. Lactobacillus and Bacillus cereus tended to decrease over the aging period. The common fungus and bacterium were Aspergillus oryzae and Tetragenococcus halophilus, respectively. After the aging period, the predominant fungi were Candida versatilis, Candida apicola, and Debaryomyces hansenii. The predominant bacteria were Tetragenococcus halophilus and Cronobacter sakazakii.

• Journal of Food Hygiene and Safety
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• v.23 no.2
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• pp.108-112
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• 2008

A survey of total aflatoxin levels was conducted on 158 samples (nuts, fermented foods and their processed products) collected in local markets in Gyeonggi-do and Domestic Internet Site. The total aflatoxins were quantified by the immunoaffinity column clean-up method followed by high performance liquid chromatography (HPLC)-fluorescence detector (FLD). Aflatoxins were found in 45(28.5%) samples including 34 nuts and nut products, 7 soybean pastes, 1 meju, 1 bean product and 2 corn snacks with a range of $0.02{\sim}3.96\;{\mu}g/kg$. These results show that the contamination level of aflatoxin in foods consumed in Korea is low compared with the standard in Korea Food Code($10\;{\mu}g/kg$ as aflatoxin $B_1$). Aflatoxin $B_1$ content was increased in peanuts and com snacks during storage but it was decreased in doenjang (soybean paste).

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.5
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• pp.749-755
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• 2014

Exopolysaccharides (EPSs) have been widely used in the food industry as viscofying, stabilizing, and emulsifying agents as well as in the pharmaceutical industry for their immunomodulatory, anti-tumor, and anti-inflammatory effects. A total of 458 lactic acid bacteria (LAB) strains isolated from several kinds of soybean pastes were screened for the production of homo-EPS (HoPS). LAB isolates were primarily screened using thin layer chromatography (TLC) and further screened polymerase chain reaction (PCR) targeting genes involved in HoPS production. Six LAB isolates producing high amounts of HoPS were identified by TLC. Among these isolates, glucansucrase gene was amplified in two strains (JSA57, JSB22), whereas the fructansucrase gene was detected in three strains (JSA57, JSB22, JSB66). After isolating the strains, their morphological characteristics and 16S rDNA sequences were determined. Six species were identified as L. alimentarius HSB15, L. plantarum JSA22, L. pentosus JSA57, L. brevis JSB22, L. alimentarius JSB66, and L. parabrevis JSB89. To evaluate the potential probiotic properties of these LAB, their survival rates against a simulated intestinal environment were determined. After 2 hr of incubation in artificial gastric juice, survival rates of JSA57, JSB90, JSB22, and JSB66 were all greater than 50%. After 2 hr of incubation in bile juice, viable cell count of JSB22 was similar with initial vial cell counts. Growth of the six LAB was screened in arabino-oligosaccharide (AOS)-containing MRS broth. Results showed that growth of the isolates selectively increased after culture in AOS-containing media. Strain JSB22 (6 hr), JSB66 (6 hr), HSB15 (20 hr), and JSA22 (29 hr) showed maximum growth rate. Especially, JSB22 showed the highest growth rate. These results suggest that EPS-producing LAB isolated from Deonjang could be applied as synbiotics.