• Journal of Environmental Health Sciences
• /
• v.20 no.3
• /
• pp.49-53
• /
• 1994

To isolate the ochratoxin A producing strains from agricultural products and soil in Youngnam districts, rice (37), unhulled rice (10), barley (20), unhulled barley (3), corn (21), soil (26), meju (25), malt (8), soybean (26) and peanut (15) were collected from homes and markets of Youngnam districts through September 1992 to November 1992. 187 strains of Aspergillus spp. and Penicillium spp. were isolated from 191 samples. As a result of screening by TLC, 36 strains expressed fluorescent spot and a same Rf value of standard ochratoxin A, and 9 strains of them were identified as ochratoxin A producing strains by HPLC.

• Food Science and Biotechnology
• /
• v.14 no.5
• /
• pp.576-580
• /
• 2005

Ten yeast strains affecting doenjang flavor were isolated from soybean fermented foods (traditional meju and doenjang), among which Zygosaccharomyces sp. Y-2-5, showing excellent growth, glucose consumption, pH, and flavor production, was selected. Higher alcohols produced by Zygosaccharomyces sp. Y-2-5 related to flavor were 2-propanol, 1-propanol, 2-methyl-1-propanol, 1-butanol, and 3.3-dimethyl-2-butanol. Optimal culture conditions for Zygosaccharomyces sp. Y-2-5 were 10% (w/v) NaCl, pH 4.0, 3.0% (w/v) glucose concentration, and inoculation time day 0 or 15 doenjang fermentation.

• KSBB Journal
• /
• v.16 no.2
• /
• pp.158-162
• /
• 2001

A halotolerant and extracellular protease-producing yeast was isolated from traditional Meju and identified as a strain of Hansenular polymorpha by investigating its microbiological characteristics. The optimum pH, temperature and NaCl concentration reauired for the growth of Hansenular polymorpha S-9 were found to be pH 6.0, 30$^{\circ}C$ and 0.5 M, respectively. Extracellular protease was produced maximally at 10 U ml(sup)-1 when Hansenular polymorpha S-9 was grown on the medium containing 1.0% beef extract and 0.1 M NaCl for 12 hr at 30$^{\circ}C$. About 13% of the angiotensin-converting enzyme (ACE) inhibitory activity was shown in the hydrolysates which were obtained from the digestion of soybean protein (6 mg) for 6 hr at 30$^{\circ}C$ by the crude enzyme (1 U).

• Journal of Microbiology and Biotechnology
• /
• v.12 no.4
• /
• pp.649-656
• /
• 2002

Fibrinolytic microorganisms were screened from 42 samples of Korean fermented food (7 kinds of Chungook-jang, 14 kinds of commercial Doen-Jang, 5 kinds of home-made Doen-jang, and 16 kinds of Jeot-gal), 15 samples of Japanese fermented food (5 kinds of home-made soybean paste, and 10 kinds of Natto), and 19 samples of Indonesian fermented food (Tempe) as well as starters of Meju (500 microflora from Korea, and 22 from China). Initially, 11 isolates with strong fibrinolytic activity were selected for further characterization. The fibrinolytic activity of the 11 isolates ranged from 89 to 199% of standard plasmin. Four strains, M5l from Korean fermented food (Meju), I 1-1, I 1-4, and I 5-1 from Indonesian fermented food (Tempe), were chosen based on the degree of activity and reproducibility, and identified as Staphylococcus sciuri, Citrobacter or Enterobacter, Enterococcus faecalis, and Bacillus subtilis, respectively. The first two isolates are pathogenic stains while the latter two are considered as GRAS (Generally Recognized As Safe). Fibrinolytic activity of E. faecalis, characterized and designated as BRCA-5, reached a maximum, when the producer was cultivated in Ml7 broth supplemented with 1.0% glucose for 5 h at 37$^{\circ}C$ with shaking at 180 rpm. Compared to commercial fibrinolytic enzymes, the cell-free culture supernatant of 5. faecaiis BRCA-5 showed stronger activity than plasmin and streptokinase, but similar degree of specific activity as nattokinase and urokinase, aud it also demonstrated anticoagulant and antiplatelet activity ex vivo. These features of E. faecalis make it an attractive agent as a biomaterial for health-promoting foods.

• Korean Journal of Food Science and Technology
• /
• v.24 no.5
• /
• pp.477-481
• /
• 1992

As a series of fundamental research projects to produce doenjang (Korean fermented soy paste) of better quality, two kinds of doenjang were manufactured from a traditional meju (Korean soy bean koji) and the mixed with Aspergillus oryzae and Bacillus natto, and histological changes in the cell structures of soy bean of the two were reported doenjang samples were observed and compared during the entire period of fermentation processes. Cell walls of the soy bean were ruptured by pressure and heat during the pressure cooking process and some of them were observed to have the ghost-like shapes. Remarkable differences in the plasmolysis of the cytoplasms were observed between the seed coat and the inner part of soy bean. Small vacuoles resulting from the fusion of the glycoprotein globules by protease and from the hydrolysis of the starch granules by amylase were also observed. Penetration of microorganisms was transferred from the seed coat to the inside of soy bean as the fermentation proceeded. Slimy substances were observed on the seed coat and the parenchyma cells of soy bean fermented with the mixed with Aspergillus oryzae and Bacillus natto. Cell walls of soy bean became difficult to stain and they showed unusual, polygonal shapes as the fermentation proceeded. Samples fermented with the mixed with Aspergillus oryzae and Bacillus natto showed more remarkable tendencies than traditional meju.

• Korean Journal of Food Science and Technology
• /
• v.23 no.5
• /
• pp.572-577
• /
• 1991

Fermented Korean soybean foodstuffs(12 samples of meju, 28 samples of doenjang and 28 samples of kanjang) which collected nation wide in Korea, were used to isolate of fungi. And the fungi producing ochratoxin A(OA) among isolated fungi were identified. Of total 222 fungi isolated in each samples, the production rate of OA was 17.7%(39/222). Four fungi out of 39 isolates which production OA showed a higher amount of ochratoxin A. From these results, four kinds of fungi producing large quantities of OA were Penicillium spp., Phialotubus microsporus, Eupenicillium lapidosum, and Paecilomyces variotti, respectively. Four fungi showed the optimum growth at water activity($a_{w}$) of 0.99, but production of OA was almost inhibited at $a_{w}$, of 0.85. Furthermore, three fungi except P. variotti showed the optimum growth at $30^{\circ}C$, while OA production inhibited at same temperature. The optimal pH for toxin production except P. variotti was 6.5. Also, toxin production was not greatly influenced by pH.

• Journal of Life Science
• /
• v.14 no.4
• /
• pp.553-559
• /
• 2004

To improve quality as a food source and functional properties of traditional fermented soybean paste (Doenjang), the Korean herb medicines (group I ∼ IV) extracted at 121$^{\circ}C$ for 2.5 hours were used as brine sources. Capsule Meju were fermented in cool brines with three different concentration (group A, B and C) of the extracts at room temperature for 3 months in large earthenware jars. The effect of traditional soybean Doenjang (refer as DHM below) supplemented with the extract of herb medicines on the food quality and chemical characteristics were examined. General composition of DHM (moisture 58.2%∼61.9%, pH 5.32∼5.56, total acidity 3.07∼3.70 ml, salt 11.7∼13.9%) did not differ from those of control (moisture 61.9%, pH 5.50, total acidity 3.25 ml, salt 12.6%). Concentration of reducing sugar, crude protein, crude lipid and amino type nitrogen were higher in DHM than those of control without addition of the extracts. Water insoluble-brown index showed no difference by the extracts. However, the former had higher water soluble-brown index than the latter, and within the DHM, groups I and II were higher than groups III and IV. Lightness values (L) of Hunter color index in groups I and II were 24.32 and 31.04, respectively. Redness values (a) of all DHMs were lower than that of control. Yellowness value (b) of groups III and IV were similar to that of control group, and Hunter b values of group I and II were lower than that of control.

• Journal of Food Hygiene and Safety
• /
• v.13 no.3
• /
• pp.313-317
• /
• 1998

This study was perfonned to investigate the possible effect of Bacillus subtilis which is the predominant species of bacteria in Korean soy sauce, soy paste, and Meju (soybean cake) on the growth and aflatoxin production of Aspergillus parasiticus ATCC 15517. The microorganisms were grown in a modified APT broth and incubated at $30^{\circ}C$ for 12 days. Aflatoxins were determined using high performance liquid chromatography (HPLC). A remarkable inhibition of the growth of Aspergillus parasiticus was observed during the incubation period when in the presence of B. subtilis (mixed culture). Dry mycelial weight in the mixed culture was significantly reduced by 85.3% in comparison to the control at the end of the incubation period (p<0.01). Lower levels of aflatoxins were found in the mixed culture than in the monoculture. At the end of the incubation period aflatoxin production was significantly inhibited by more than 50% (p<0.05). These results indicate that B. subtilis mainly inhibites the growth and aflatoxin production of toxigenic Aspergillus in Meju, soy sauce and soy paste. Although its effect on aflatoxin production was less pronounced, we could expect more inhibition by another bacteria related with fermentation in Meju.

• Journal of Life Science
• /
• v.22 no.5
• /
• pp.605-612
• /
• 2012

Spore-forming bacteria are being used as probiotic supplements for human and animal use, due to their low pH stability and ability to survive the gastric barrier. In this study, the BCNU 9028 strain was screened from meju, a Korean fermented soybean food starter. Biochemical and physiological characteristics, as well as 16S rDNA sequence analyses, indicate that this strain belongs to the genus $Bacillus$. $Bacillus$ sp. BCNU 9028 showed a 92% survivability at pH 2.5 and could also withstand 0.3% ox bile. Furthermore, it was postulated that $Bacillus$ sp. BCNU 9028 could prevent biofilm formation and adherence of food-borne pathogens such as $Listeria$ $monocytogenes$, $S.$ $aureus$ and $E.$ $coli$ on the basis of its autoaggregation and coaggregation capacity with food-borne pathogens. It was shown that BCNU 9028 has good abilities to adhere to the intestinal tract from its hydrophobic character (63.3%). The $Bacillus$ sp. BCNU 9028 strain especially elicited antibacterial activity against both Gram-positive and -negative pathogens. These findings suggested that the $Bacillus$ sp. BCNU 9028 strain could be used as a potential probiotic.

• Korean Journal of Food Science and Technology
• /
• v.32 no.1
• /
• pp.154-160
• /
• 2000

Protease production and its characteristics were investigated with Bacillus subtilis PCA20-3 which was isolated from Korean traditional meju. The optimum culture conditions of Bacillus subtilis PCA20-3 for the production of the protease were as follow: 0.2% soytone, 2% starch, 0.1% $(NH_4)_2SO_4,\;0.2%\;CaCl_2,\;0.01%\;yeast\;extract,\;0.1%\; K_2HPO_4,\;0.1%\;KH_2PO_4,\;pH\;7.0,\;30^{\circ}C$ and 20 hrs. The optimum pH and temperature for enzyme activity of protease producing Bacillus subtilis PCA20-3 were pH 8.0-10.0 and $55^{\circ}C$, respectively. The enzyme was relatively stable at pH $6.0{\sim}11.0$ and at temperature below $50^{\circ}C$. The activity of the enzyme was inhibited by $Fe^(2＋)\;and\;Cu^(2＋)$. 2 mM phenymethanesulfonyl fluoride inhibited 89.2% of enzyme activity. This indicates that the enzyme is serine protease. The $K_m$ value was $5\;{\times}\;10^{-4}\;M,\;V_{max}\;value\;was\;100\;{\mu}g/min$. This enzyme hydrolyzed casein more rapidly than bovine serum albumin.