• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.9
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• pp.1461-1466
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• 2013

In this study, we ascertained the characteristics of crude protease extracted from fruits (fig, kiwifruit and pineapple) as well as traditional Korean fermentation starters (bio nuruk, traditional nuruk, meju and rice koji) to determine their suitability for industrial application. Crude protease extracted from traditional Korean fermentation starters was found to have a higher optimum temperature ($70^{\circ}C$) and salt concentration (1~3%) but a lower optimum pH (3~6) value compared to the corresponding values for the protease extracted from fruits. On comparison, the total activities of protease per gram unit follow the order: bio nuruk> rice koji> traditional nuruk> fig> pineapple> meju> kiwifruit. Based on our results, we conclude that protease extracted from traditional Korean fermentation starters has potential for application in food industry, for example, as a meat tenderizer for sausage manufacturing and as a protease for cheese production.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.94-99
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• 2001

Kochujangs(fermented hot pepper-soybean paste) were prepared either using traditional meju (koji for kochujang) or controlled meju fermented by pure isolates (P-1, P-2), which were screened from traditional meju collected at Sunchang area. The isolates were characterized for their superiority on amylase and protease activities, and overall flavor of the culture on cooked soybean. Bacterial cell counts were not different in all treatments of kochujang during fermentation. The mold counts of each treatment dropped to undetectable level after 40 and 60 days of fermentation, respectively. Heat treatment($60^{\circ}C$, 15 min) before fermentation stopped gas formation and had no effect on bacterial cell count, but the growth of yeast was depressed. Total accumulative volume of gas produced during kochujang fermentation was depended on load of yeast in kochujang and the kochujang using P-2 koji produced least amount of gas among all treatments. The amylase and protease activities of kochujang were not significantly different among traditional and controlled kochujangs.

• The Korean Journal of Food And Nutrition
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• v.8 no.3
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• pp.206-211
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• 1995

Three kinds of soy sauce were prepared using the brick type of conventional menu(A), the brick type of meju of Aspergillus oryzae (B) and the grain type of menu Aspergillus oryzae (C). Organic acid and fatty acid were analyzed In accordance to aging time of those products Citric acid, lactic acid, acetic acid, malonic acid, butyric acid, oxalic acid, and propionic acid were dejected in all kinds of soy sauce. The content of lactic acid was shown higher than those of any other organic acids. The content of lactic acid was much higher at beginning of preparation and at 180 days in soy sauce B than any other conditions. The content of acetic acid was much higher at beginning of preparation, at 120 days in soy sauce C and at 180 days in soy sauce B than any other conditions. The content of citric acid was highest at beginning preparation in soy sauce C, and that was highest in soy sauce B except beginning preparation to 120 days. Myristic, palmitic, stearic, oleic, linoliic, linolenic, arachidonic acid were detected in all kinds of soy sauce after 180 days. The content of oleic acid were shown 32.59∼53.79% in soy sauce B and in soy sauce C. The content of stearic acid was shown 49.7oA In soy sauce A. Linolinec acid and arachidonic acid were detected in only soy sauce C.

• Korean journal of food and cookery science
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• v.25 no.1
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• pp.90-97
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• 2009

Changes in the quality characteristics of doenjang prepared with a meju containing components of Acanthopanax senticosus, Angelica gigas and Corni fructus during storage were evaluated. Three types of doenjang produced using each of these components showed lower Hunter's L and a values than the values of the control during the initial stage of storage: however, these values were similar to those of the control after 60 days of storage. Doenjang containing A. gigas showed a similar degree of browning to that of the control during the early stage of storage, while the degree of browning observed in the other samples was much higher than that og the control during this period. Despite these initial differences, the browning in all samples became similar after extended storage. The level of acidity increased gradually for up to 60 days, after which it decreased slightly. The pH of all treatments decreased with storage time. The amino-N contents of all types of doenjang increased gradually, reaching peak values after 60 days. Doenjang with A. senticosus and A. gigas had a strong characteristic flavor that reduced the native flavor of doenjang. Doenjang with C. fructus showed a similar overall palatability to that of the control.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.438-446
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• 2020

Meju and nuruk (respectively soybean and malt) are traditional Korean fermentation starters that are vulnerable to contamination by harmful microorganisms such as aflatoxigenic fungi and their associated aflatoxins (AFs). In this study, Aspergillus spp. were isolated and identified from a total of 57 meju and 18 nuruk samples collected from Korean markets. Their potential aflatoxigenicity was investigated by examining the presence of three aflatoxin biosynthetic genes (aflO, aflP, and aflR) using multiplex polymerase chain reaction (mPCR) assays. Thereafter, aflatoxin production of isolates and the natural occurrence of AFs in meju and nuruk samples were analyzed by high-performance liquid chromatography (HPLC). A total of 177 Aspergillus isolates were identified and 130 isolates were obtained from meju samples. Of these, 25 isolates (19.2%) contained all three aflatoxin biosynthetic genes, and five (20%) of these isolates produced aflatoxins. Forty-seven of the Aspergillus isolates were obtained from nuruk samples, five of which (10.6%) expressed all three AF biosynthetic genes; however, none of these strains produced AFs. HPLC analysis showed that 88% (51/58) of the meju samples and 39% (7/18) of nuruk samples were not contaminated with AFs (below limit of detection). Among the isolates isolated from meju and nuruk, there were aflatoxigenic strains containing all three aflatoxin biosynthetic genes or producing aflatoxin in medium, but the frequency of aflatoxin contamination was low in the meju and nuruk samples.

• Applied Biological Chemistry
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• v.42 no.4
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• pp.277-282
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• 1999

This study was carried out to clarify the microorganisms which participated in the fermentation of kanjang. The changes in the viable cell counts of total aerobic bacteria, lactic acid bacteria and yeasts for raw soybean, soybean during cooking, meju during cultivation, and kanjang mash during maturing were investigated along with the changes in components during those periods. Lactic acid bacteria that were found to be $6{\times}10^2\;CFU/g$ in raw soybean were disappeared after cooking process, but total aerobic bacteria were diminished from $1.9{\times}10^6\;CFU/g$ to $10^2\;CFU/g$. Aerobic bacteria of inner and outer parts of meju increased to more than $10^9\;CFU/g$. The higher viable cell counts of lactic acid bacteria in the inner parts of meju were observed than those in outer ones. On the contrary, significantly higher viable cell counts of yeasts in the outer parts of meju were found. Total nitrogen content and color density of kanjang increased by using meju with extended cultivation periods. No significant differences were observed in microbial counts between kanjang mash with aeration and non-aeration during kanajng mash maturing.

• Korean journal of food and cookery science
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• v.13 no.2
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• pp.92-98
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• 1997

Ethyl carbamate is an animal carcinogen and a by-product of fermentation. Since the highest level of ethyl carbamate was found in a traditional soy sauce sample in the previous study, soysauce was prepared in varying experimental conditions with three kinds of meju originated from different area of the country to investigate the factors affecting ethyl carbamate formation. The sample analysis methods included a semi-purification with solid-phase extraction and detection by GC-MS at SIM mode using m/z 62 fragment ion. Among the investigated factors, which includes source meju, bringing length, salt content, irradiation of visible light during bringing or storage, and storage length, source meju and storage length showed most profound effect on the formation of ethyl carbamate. Irradiation of visible light for 12 hours a day during storage lowered the concentration of ethyl carbamate compared to the soysauce kept in the dark. Meanwhile irradiation during the bringing as well as the degree of salt contents showed no effect.

• The Korean Journal of Mycology
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• v.26 no.4 s.87
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• pp.487-495
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• 1998

The mycotoxins, $Aflatoxin\;B_1(B)$ and Ochratoxin A(A), were measured from the various mejus manufactured under the artificial or natural conditions by the indirect competitive ELISA; The various fungi isolated from the Korean traditional home (KTH) made meju collected were observed to produce each mycotoxin mentioned above in the toxin producing broth, but only few in the sterilized cereals of soybean under the artificial conditions. Thus, the isolated fungi were not found to produce both A and B toxins in the artificial conditions. Particularly, the any mycotoxin was not determined at the range of 0.01 to 100 ng per gm of the mejus made under the conditions of KTH widely collected in Korea. The mycotoxins produced by the meju-fermenting fungi were seemed or speculated to be degraded in KTH's mejus under the natural conditions. The species of Mucor involved in the initial stage of fermentation were discussed to be important in the fermentations of KTH mejus.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.757-763
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• 1999

Based on the previous studies, R. stolonifer was selected for the model system of Korean soy sauce preparation process, using the fermented soybean. The system of meju fermentation was refined; the optimal conditions of temperature and relative humidity were $25^{\circ}C$ and 90%, respectively. The optimal temperature for soy sauce fermentation was evaluated to the $25^{\circ}C$ and, in the latter half of the fermentation, some aeration was observed to positively affect the sensory evaluation of soy sauce. In the sensory evaluation, the soy sauce fermented with B. subtilis and A. sojae was showed to be better than one fermented with R. stolonifer. Conditions of the pasteurization and ultrafiltration process were also established for industrialization of the soy sauce. Finally, the standard systems using the soybean fermented was, by the industrial scales, proposed for Korean traditional soy sauces.

• Journal of Microbiology and Biotechnology
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• v.27 no.2
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• pp.251-261
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• 2017

Initially, we screened 18 Aspergillus sojae-like strains from Aspergillus spp. isolated from meju (Korean traditional fermented soybean brick) according to their morphological characteristics. Because members of Aspergillus section Flavi are often incorrectly identified because of their phylogenetic similarity, we re-identified these strains at the morphological and molecular genetic levels. Fourteen strains were finally identified as A. sojae. The isolates produced protease and ${\alpha}-amylase$ with ranges of 2.66-10.64 and 21.53-106.73 unit/g-initial dry substrate (U/g-IDS), respectively, which were equivalent to those of the koji (starter mold) strains employed to produce Japanese soy sauce. Among the isolates and Japanese koji strains, strains SMF 127 and SMF 131 had the highest leucine aminopeptidase (LAP) activities at 6.00 and 6.06 U/g-IDS, respectively. LAP plays an important role in flavor development because of the production of low-molecular-weight peptides that affect the taste and decrease bitterness. SMF 127 and SMF 131 appeared to be non-aflatoxigenic because of a termination point mutation in aflR and the lack of the polyketide synthase gene found in other A. sojae strains. In addition, SMF 127 and SMF 131 were not cyclopiazonic acid (CPA) producers because of the deletion of maoA, dmaT, and pks/nrps, which are involved in CPA biosynthesis. Therefore, A. sojae strains such as SMF 127 and SMF 131, which have high protease and LAP activities and are free of safety issues, can be considered good starters for soybean fermentations, such as in the production of the Korean fermented soybean products meju, doenjang, and ganjang.