Traditional Meju Research Articles

Correlation between monosaccharide, oligosaccharide, and microbial community profile changes in traditional soybean brick (meju) fermentation

Meju is essential for making diverse traditional fermented soybean foods in Korea. To understand the changes in carbohydrates during fermentation, we aimed to identify autochthonous microorganisms from spontaneously fermented meju and compare the alterations in monosaccharides and oligosaccharides throughout the fermentation process. Microbial diversity was determined using a metabarcoding approach, and monosaccharide and oligosaccharide profiles were obtained by HPLC-Q-TOF MS and HPLC-MS/MS analyses, respectively. The dominant bacterial genera were Weissella, Lactobacillus, and Leuconostoc, while Mucor was highly abundant in the fungal community. The total monosaccharide content increased from Day 0 to Day 50, with the highest amount being 4.37 mg/g. Oligosaccharide profiling revealed the degradation of soybean dietary fiber during fermentation, and novel oligosaccharide structures were also discovered. Correlation analysis revealed that the fungus Mucor was positively related to pentose-containing oligosaccharides, galactose, and galacturonic acid, indicating that Mucor may degrade soybean dietary fibers such as xylogalacturonan, arabinogalactan, and rhamnogalacturonan. The negative relationships between the abundances of Weissella and oligo- and monosaccharides suggested that the bacteria may utilize saccharides for fermentation. These findings provide insights into the mechanisms underlying carbohydrate degradation and utilization; the key components involved in saccharide transformation that contribute to the characteristics of traditional meju were subsequently identified.

Enzymatic Activity and Amino Acids Production of Predominant Fungi from Traditional Meju during Soybean Fermentation.

To investigate the effect of the predominant fungal species from Korean traditional meju and doenjang on soybean fermentation, the enzymatic activity and amino acid production of twenty-two fungal strains were assessed through solid- and liquid-state soybean fermentation. Enzymatic activity analyses of solid-state fermented soybeans revealed different enzyme activities involving protease, leucine aminopeptidase (LAP), carboxypeptidase (CaP), glutaminase, γ-glutamyl transferase (GGT), and amylase, depending on the fungal species. These enzymatic activities significantly affected the amino acid profile throughout liquid-state fermentation. Strains belonging to Mucoromycota, including Lichtheimia, Mucor, Rhizomucor, and Rhizopus, produced smaller amounts of total amino acids and umami-producing amino acids, such as glutamic acid and aspartic acid, than strains belonging to Aspergillus subgenus circumdati. The genera Penicillium and Scopulariopsis produced large amounts of total amino acids and glutamic acid, suggesting that these genera play an essential role in producing umami and kokumi tastes in fermented soybean products. Strains belonging to Aspergillus subgenus circumdati, including A. oryzae, showed the highest amino acid content, including glutamic acid, suggesting the potential benefits of A. oryzae as a starter for soybean fermentation. This study showed the potential of traditional meju strains as starters for soybean fermentation. However, further analysis of processes such as the production of G-peptide for kokumi taste and volatile compounds for flavor and safety is needed.

Metabolite Profiling and Microbial Community of Traditional Meju Show Primary and Secondary Metabolite Differences Correlated with Antioxidant Activities.

Meju, a type of fermented soybean paste, is used as a starter in the preparation of various Korean traditional soybean-based foods. In this study, we performed Illumina-MiSeq paired-end sequencing for microbial communities and mass spectrometry analysis for metabolite profiling to investigate the differences between 11 traditional meju products from different regions across Korea. Even though the bacterial and fungal communities showed remarkable variety, major genera including Bacillus, Enterococcus, Variovorax, Pediococcus, Weissella, and Aspergillus were detected in every sample of meju. The metabolite profile patterns of the 11 samples were clustered into two main groups: group I (M1-5) and group II (M6-11). The metabolite analysis indicated a relatively higher amino acid content in group I, while group II exhibited higher isoflavone, soyasaponin, and lysophospholipid contents. The bioactivity analysis proved that the ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) radical-scavenging activity was higher in group II and the FRAP (ferric reducing antioxidant power) activity was higher in group I. The correlation analysis revealed that the ABTS activity was isoflavonoid, lipid, and soyasaponin related, whereas the FRAP activity was amino acid and flavonoid related. These results suggest that the antioxidant activities of meju are critically influenced by the microbiome and metabolite dynamics.

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.

메주에서 분리한 Lactobacillus plantarum JBE245를 이용한 사과 발효 음료 제조

메주에서 분리한 Lactobacillus plantarum JBE245를 이용한 사과 발효 음료 제조

The Mycobiota of Air Inside and Outside the Meju Fermentation Room and the Origin of Meju Fungi

The fungi on Meju are known to play an important role as degrader of macromolecule of soybeans. In order to elucidate the origin of fungi on traditional Meju, mycobiota of the air both inside and outside traditional Meju fermentation rooms was examined. From 11 samples of air collected from inside and outside of 7 Meju fermentation rooms, 37 genera and 90 species of fungi were identified. In outside air of the fermentation room, Cladosporium sp. and Cladosporium cladosporioides were the dominant species, followed by Cladosporium tenuissimum, Eurotium sp., Phoma sp., Sistotrema brinkmannii, Alternaria sp., Aspergillus fumigatus, Schizophyllum commune, and Penicillium glabrum. In inside air of the fermentation room, Cladosporium sp., Aspergillus oryzae, Penicillium chrysogenum, Asp. nidulans, Aspergillus sp., Cla. cladosporioides, Eurotium sp., Penicillium sp., Cla. tenuissimum, Asp. niger, Eur. herbariorum, Asp. sydowii, and Eur. repens were collected with high frequency. The concentrations of the genera Aspergillus, Eurotium, and Penicillium were significantly higher in inside air than outside air. From this result and those of previous reports, the origin of fungi present on Meju was inferred. Of the dominant fungal species present on Meju, Lichtheimia ramosa, Mucor circinelloides, Mucor racemosus, and Scopulariopsis brevicaulis are thought to be originated from outside air, because these species are not or are rarely isolated from rice straw and soybean; however, they were detected outside air of fermentation room and are species commonly found in indoor environments. However, Asp. oryzae, Pen. polonicum, Eur. repens, Pen. solitum, and Eur. chevalieri, which are frequently found on Meju, are common in rice straw and could be transferred from rice straw to Meju. The fungi grow and produce abundant spores during Meju fermentation, and after the spores accumulate in the air of fermentation room, they could influence mycobiota of Meju fermentation in the following year. This could explain why concentrations of the genera Aspergillus, Eurotium, and Penicillium are much higher inside than outside of the fermentation rooms.

Bioconversion of Ginsenosides from Red Ginseng Extract Using Candida allociferrii JNO301 Isolated from Meju

Red ginseng (Panax ginseng), a Korean traditional medicinal plant, contains a variety of ginsenosides as major functional components. It is necessary to remove sugar moieties from the major ginsenosides, which have a lower absorption rate into the intestine, to obtain the aglycone form. To screen for microorganisms showing bioconversion activity for ginsenosides from red ginseng, 50 yeast strains were isolated from Korean traditional meju (a starter culture made with soybean and wheat flour for the fermentation of soybean paste). Twenty strains in which a black zone formed around the colony on esculin-yeast malt agar plates were screened first, and among them 5 strains having high β-glucosidase activity on p-nitrophenyl-β-D-glucopyranoside as a substrate were then selected. Strain JNO301 was finally chosen as a bioconverting strain in this study on the basis of its high bioconversion activity for red ginseng extract as determined by thin-layer chromatography (TLC) analysis. The selected bioconversion strain was identified as Candida allociferrii JNO301 based on the nucleotide sequence analysis of the 18S rRNA gene. The optimum temperature and pH for the cell growth were 20~30°C and pH 5~8, respectively. TLC analysis confirmed that C. allociferrii JNO301 converted ginsenoside Rb1 into Rd and then into F2, Rb2 into compound O, Rc into compound Mc1, and Rf into Rh1. Quantitative analysis using high-performance liquid chromatography showed that bioconversion of red ginseng extract resulted in an increase of 2.73, 3.32, 33.87, 16, and 5.48 fold in the concentration of Rd, F2, compound O, compound Mc1, and Rh1, respectively.

콩 코오지를 이용한 된장의 품질 특성

This study investigated the quality characteristics and sensory evaluation of Doenjang samples made of soybean koji and prepared with Bacillus subtillus 3-B-1 and/or Aspergillus oryzae 6-M-1 isolated from traditional Meju, to replace the koji with wheat flour. Among the quality characteristics of doenjang during its fermentation at 30°C for 40 days, its moisture decreased by degrees, but its amino-type nitrogen and reducing sugar increased by degrees. The color of the doenjang made of koji and prepared with Aspergillus oryzae 6-M-1 changed more significantly than that of the doenjang with Bacillus subtilis 3-B-1. The viable cell and mold counts increased by degrees during the fermentation. The results of the sensory evaluation of the doenjang made with koji and prepared with Aspergillus oryzae 6-M-1 did not significantly differ from those of the doenjang with Bacillus subtilis 3-B-1 and of the commercial doenjang. These results showed the possibility of preparing doenjang with soybean koji instead of wheat flour koji.

제조방법이 다양한 시판 재래 및 양조 간장의 관능적 특성

Soy sauce, a basic ingredient in Asian cuisine, is made of fermented soybeans, salt, water, and barley or wheat flour. The sensory characteristics of soy sauce are not only determined through its main ingredients but also by various flavor compounds produced during the fermentation process. This study was conducted to identify the sensory attributes of five different commercial soy sauce samples that differ in Meju types (traditional Meju or modified Meju) and usage types. Thirty three sensory attributes, including appearance (1), odor (16), flavor (14), and mouthfeel (2) attributes, were generated and evaluated by eight trained panelists. The collected data were analyzed by analysis of variance and principal component analysis. There were significant differences in the intensities of all sensory attributes among the soy sauce samples. Soy sauce made with traditional Meju had high intensity of fermented fish, beany, musty odors and salt, Cheonggukjang, fermented fish flavors. Whereas two soy sauces made with modified Meju were strong in alcohol, sweet, Doenjang, roasted soybean flavors. Two soy sauces for soup made with modified Meju had medium levels of briny, sulfury, fermented odors and bitter, chemical flavors and biting mouthfeel characteristic.

Anti-obesity effects of traditional and standardized meju in high-fat diet-induced obese C57BL/6J mice

The aim of the study was to evaluate the anti-obesity effects of two types of meju in diet induced obese C57BL/6J mice. Animals were randomly divided into 4 dietary group (n = 10); normal diet, high fat diet with 30% soybean, high fat diet with 30% traditional meju, high fat diet with 30% standardized meju. After 16 weeks, after animals were sacrificed. It was observed that the high fat diet with 30% traditional meju and high fat diet with 30% standardized meju significantly reduced body weight gain, epididymal fat weight, serum triglyceride along with serum insulin and leptin levels compared to the high fat diet with 30% soybean. And also, the expression levels of hepatic lipid anabolic genes were significantly decreased in the high fat diet with 30% traditional meju and high fat diet with 30% standardized meju compared to the high fat diet with 30% soybean. In conclusion, the assessment of all the obesity markers strongly advocate the anti-obesity effect of traditional as well as standardized meju in diet induce obesity conditions.

메주에서 분리한 검은 Aspergillus 균주의 동정

검은 Aspergillus 속균은 동양의 발효산업에서 매우 중요한 곰팡이로서 식품산업에 관련된 검은 Aspergillus를 흑국균이라고 한다. 흑국균은 A. luchuensis, A. niger, A. tubingensis로 구성이 되어 있는데 이 중에서 A. luchuensis는 동양의 발효산업에서 매우 중요한 곰팡이로 알려져 있다. 우리나라 전통 된장과 간장의 주요 원료가 되는 메주에서도 검은 Aspergillus가 흔히 발견되었다. 33균주의 검은 Aspergillus가 2008년부터 2011년 사이에 전국적으로 수집한 98개의 완성메주로부터 분리되었고 추가로, 발효과정에 있는 메주로부터 검은 Aspergillus 21균주를 분리하였다. <TEX>${\beta}$</TEX>-tubulin과 calmodulin 유전자 염기서열 분석을 통하여 이들을 동정한 결과 이들은 A. niger 21균주, A. luchuensis 14균주, A. tubingensis 10균주, A. welwitschiae 9균주로 동정되었다. 이 중 A. luchuensis는 생장이 활발하고 단백질, 지방, 탄수화물 분해력이 높은 것으로 조사되어 이들의 산업적 응용에 대한 추가의 연구가 필요한 것으로 사료된다. Black Aspergillus is important fungus for oriental fermentation industry. Black Aspergillus was frequently isolated from Korean traditional Meju, a fermented soybean starting material for soy sauce and soybean paste. Thirty three strains were isolated from 98 finished Meju collected in various regions of Korea from 2008 to 2011, and 21 strains were isolated from in-process Meju at various farms from 2010 to 2011. The isolated black Aspergillus were identified using DNA sequences of partial <TEX>${\beta}$</TEX>-tubulin and calmodulin genes. Of 54 black Aspergillus strains, 14 strains were identified as A. luchuensis and the others were composed of A. niger (n = 21), A. tubingensis (n = 10), and A. welwitschiae (n = 9).

Mycoflora of Soybeans Used for Meju Fermentation

Diverse fungi are present in Korean traditional meju and they are known to play an important role in fermented soybean products. To determine the origin of the fungi in meju, we examined the mycoflora of soybeans from 10 traditional meju factories. The samples were untreated or treated with sodium hypochlorite, and placed on malt extract agar (MEA), dichloran 18% glycerol agar (DG18), and dichloran rose bengal chloramphenicol agar (DRBC) medium. A total of 794 fungal strains were isolated and they were identified as 41 genera and 86 species. From sodium hypochlorite untreated soybeans, the genera, Cladosporium (55%), Eurotium (51%), Fusarium (33%), Penicillium (22%), and Aspergillus (exclusion of Eurotium) (20%), were mainly isolated, and Eurotium herbariorum (22%), Eurotium repens (18%), Cladosporium tenuissimum (18%), F. fujikuroi (18%), Aspergillus oryzae/flavus (7%), and Penicillium steckii (6%) were the predominant species. In case of sodium hypochloritetreated soybeans, Eurotium (31%) and Cladosporium (5%) were frequently isolated, but Aspergillus (excluding Eurotium), Penicillium and Fusarium which were frequently isolated from untreated soybeans, were rarely isolated. Eurotium herbariorum (21%), Eurotium repens (8%), and Cladosporium tenuissimum (3%) were the predominant species. Of the 41 genera and 86 species isolated from soybeans, 13 genera and 33 species were also found in meju. These results suggest that the fungi on soybeans may influence the mycoflora of meju.

Effect of fermented soybean curd residue (FSCR; SCR-meju) byaspergillus oryzaeon the anti-obesity and lipids improvement

In this study, we designed to confirm the dietary effect of anti-obesity of fermented soybean curd residue (FSCR; SCRMeju; Biji-meju) by A. oryzae, which is well known as a Korean traditional meju microbe. We observed that body weight gain, serum and hepatic lipid profile, as well as the activity of ROS generating enzyme and ROS scavenging enzyme in high-fat diet induced obese mice fed experimental diet (SCR and SCR-meju). Body weight gain and epididymal fat weight of HC (high-fat diet control) was markedly higher than that of NC (Normal control). Conversely, body weight gain and epididymal fat weight of the SCR (Biji) and SCR-meju (Biji-meju) group was significantly lower than that of HC; these of the SCR-meju group was lower than that of the SCR group. Furthermore, serum TG and total-cholesterol and LDLcholesterol contents of SCR and SCR-meju groups were lower than that of HC, and HDL-cholesterol level of the SCRmeju group was significantly higher than that of HC. In conclusion, although precise mechanisms of the antiobese effects of SCR-meju in this study are unknown, the present study provides an experimental evidence that SCR-meju may prevent obesity and obesity related metabolic syndromes, such as hyperlipidemia, hypertension and diabetes, and liver disease by high-fat diet. Nevertheless, further study in this filed will be needed.

Mass Spectrometry-Based Metabolite Profiling and Bacterial Diversity Characterization of Korean Traditional Meju During Fermentation

The metabolite profile of meju during fermentation was analyzed using mass spectrometry techniques, including GC-MS and LC-MS, and the bacterial diversity was characterized. The relative proportions of bacterial strains indicated that lactic acid bacteria, such as Enterococcus faecium and Leuconostoc lactis, were the dominant species. In partial least-squares discriminate analysis (PLS-DA), the componential changes, which depended on fermentation, proceeded gradually in both the GC-MS and LC-MS data sets. During fermentation, lactic acid, amino acids, monosaccharides, sugar alcohols, and isoflavonoid aglycones (daidzein and genistein) increased, whereas citric acid, glucosides, and disaccharides decreased. MS-based metabolite profiling and bacterial diversity characterization of meju demonstrated the changes in metabolites according to the fermentation period and provided a better understanding of the correlation between metabolites and bacterial diversity.

Aspergillus cibarius sp. nov., from traditional meju in Korea

Aspergillus cibarius sp. nov. isolated from meju, a brick of dried fermented soybeans in Korea, is described. The species was also found from black bean, bread and salami in the Netherlands. It is characterized by abundant yellow to reddish brown ascomata and small lenticular ascospores (4.5-5.5 μm) with a wide furrow, low equatorial crests and tuberculate or reticulate convex surface. The species was resolved as phylogenetically distinct from the other reported Aspergillus species with an Eurotium teleomorph based on multilocus sequence typing using partial fragments of the β-tubulin, calmodulin, ITS and RNA polymerase II genes.

Aroma characteristics of fermented Korean soybean paste (Doenjang) produced by Bacillus amyloliquefaciens

Four strains of Bacillus amyloliquefaciens with high proteolytic, fibrinolytic, and angiotensin converting enzyme (ACE) inhibitory activities were used to make Bacillus-koji suitable for the production of functional doenjang. Volatile compounds in Bacillus-koji doenjang were analyzed by headspace-solid phase microextraction-GC-MS (HS-SPME-GC-MS) to compare the aroma profile with those of commercially produced doenjang made with traditional meju and with modified koji. Extraction temperatures for SPME were adjusted to 30 and 90°C. Commercial samples contained significantly more esters than Bacillus-koji doenjang and demonstrated a more complex volatile compound profile. Pentanoic acid, butanoic acid, or 2/3-methyl butanoic acid, known as off-flavor compounds in doenjang, were not detected in one of the Bacillus-koji doenjang when extracted at 30°C. From the sensory test results, the cheese character was less intense in Bacillus-koji doenjang than commercial samples, although not all sensory properties projected a significant difference.

Zygomycota associated with traditional meju, a fermented soybean starting material for soy sauce and soybean paste

Various zygomycota species were detected during a study of the mycobiota of meju, a brick of dried fermented soybeans, used in Korean cuisine. Two hundred and sixty-eight strains were isolated from 98 finished meju products collected in various regions of Korea from 2009 to 2011, and 96 strains were isolated from in-process meju on various farms from 2010 to 2011. The isolated zygomycota were identified using phenotypic characteristics combined with DNA sequences of the internal transcribed spacer regions of ribosomal DNA and the D1/D2 nuclear ribosomal large subunit. Of 364 zygomycota strains, 108 were identified as Mucor circinelloides, 96 as M. racemosus, 60 as Lichtheimia ramosa, 22 as Rhizopus stolonifer, 16 as Lichtheimia corymbifera, and the other 62 strains comprised 10 other species. The psychrotrophic species, Mucor circinelloides and M. racemosus were predominantly present during low temperature fermentation (LTF) and the thermotolerant species Lichtheimia ramosa and Rhizomucor species were predominant during high temperature fermentation (HTF). The results suggest that temperature has a large influence on the zygomycota composition during the fermentation process of meju.

Optimization for rice koji preparation using aspergillus oryzae CJCM-4 isolated from a korean traditional meju

To obtain a useful mold strain in rice-doenjang production, enzyme activities were investigated in rice and wheat koji prepared with 13 different strains isolated from traditional Korean meju. The CJCM-4 strain, which had been selected as a superior strain for the production of protease, was identified as Aspergillus oryzae by the gene sequence of the ITS-5.8S rDNA region as well as aflatoxin production capacity. The enzyme activities of koji prepared with CJCM-4 according to the polishing degree of rice bran were examined. The enzyme activities of koji prepared with 70% milling degree of rice bran were higher than those of other kojis. Protease activity showed its highest level on day 3 at 30°C. Glucoamylase activity showed its highest level on day 2 at 30°C. The optimum enzyme production of koji was determined at different conditions such as incubation time, temperature, moisture, and inorganic salt content. The optimum ratio of water added to the rice for the production of enzymes was 35% on the dry basis of the rice, and the optimum temperature was 25°C. When inorganic salts were added to increase enzyme activity, the combined addition of 0.15% CaCO3 and 0.05% NaH2PO4 resulted in the highest enzyme activities.

Simultaneous Enhancement of Free Isoflavone Content and Antioxidant Potential of Soybean by Fermentation with Aspergillus oryzae

In order to determine the fungal strain and fermentation period which produce the highest antioxidant activity of fermented soy product, soybean was fermented with Aspergillus oryzae NL 5 isolated from Korean traditional meju produced in Sunchang Yeastopia Land in Korea, and was subjected to analyzing isoflavone profiles and assaying antioxidant activity. Antioxidant potential of the samples was evaluated by ferric reducing antioxidant power assay, 2,2'-azinobis (2-ethylbenzthiazoline-6-sulfonic acid) radical scavenging activity and total phenolic contents. In addition, antioxidant assay using fluorescent probes, 2',7'-dichlorofluorescin diacetate and dihydroethidium, in HepG2 cells was conducted for the samples. The results showed that both high isoflavone variety Aga 3 and medium isoflavone variety Daewon of soybean fermented with Asp oryzae NL5 for 4 to 5 d showed the highest increase in free isoflavone contents, together with the highest antioxidant activity. In conclusion, the antioxidant activity of fermented soy was proportional to the concentration of free isoflavones, and was significantly influenced by total isoflavone content of soybean variety and fermentation period. Practical Application: Isoflavone profile and antioxidant capacity of soybean were widely variable during fermentation with Asp oryzae, and thereby it is recommended that meju (or koji) preparation condition, in particular, fermentation time is carefully optimized to maximize the antioxidant capacity of soy products fermented by Asp oryzae.

Aspergillus속과 Bacillus subtilis를 이용한 된장메주 발효 중 품질 특성

메주의 산업화를 위해, 종균으로서는 A. oryze와 A. sojae 그리고 B. subtilis를 병용하고, 습도조절과 함께 <TEX>$28^{\circ}C$</TEX>에서 12일간 발효하면서 메주의 품질특성 변화를 조사하였다. 그리고 이들 종균 접종 메주와 순창 고추장 민속마을에서 입수한 된장용 전통메주의 효소 활성도를 비교하였다. 즉, A. oryzae를 접종한 메주(=AO메주), A. oryze와 B. subtilis를 접종한 메주(AOBS메주), A. sojae를 접종한 메주(=AS메주), A. sojae와 B. subtilis를 접종한 메주(=ASBS메주)를 12일 동안 발효시키면서 메주별로 품질 변화를 관찰하였다. 세균수와 곰팡이수는 각각 발효초기 6.48~6.69 log cfu/g, 5.00~5.71 log cfu/g에서 발효 2일에 8 log cfu/g 이상, 6 log cfu/g 이상으로 증가한 후 발효 12일 까지 세균수는 유지되었고, 곰팡이수는 감소 경향을 보였다. 아미노태 질소 함량은 발효 2일에 430.5~577.5 mg% 범위를 나타내었다. 중성 protease 활성도는 전통메주 <TEX>$1,258.0{\pm}38.8$</TEX>, AS메주 <TEX>$1,238.3{\pm}38.6$</TEX>, AO메주 <TEX>$1,204.1{\pm}24.1$</TEX>, ASBS메주 <TEX>$1,040.6{\pm}10.6$</TEX>, AOBS메주 <TEX>$1,033.5{\pm}11.2$</TEX> unit/g순으로 나타났다. 산성 protease활성도는 AO메주 <TEX>$1,030.1{\pm}19.1$</TEX>, 전통메주 <TEX>$1007.7{\pm}30.5$</TEX>, AS메주 <TEX>$990.9{\pm}25.0$</TEX>, AOBS메주 <TEX>$910.9{\pm}15.3$</TEX>, ASBS메주 <TEX>$888.2{\pm}15.7$</TEX> unit/g 순이었다. To industrialize meju, four kinds of meju (Korean-style soybean koji) were made with humidity-controlled fermentation for 12 days at <TEX>$28^{\circ}C$</TEX> after they were inoculated with selected strains such as Aspergillus otyzae (AO meju), Aspergillus sojae (AS meju), combined Aspergillus sojae and Bacillus subtilis (ASBS meju), and combined Aspergillus oryzae and Bacillus subtilis (AOBS meju) as starter microorganisms. The changes in the quality characteristics in the four kinds of meju were investigated during fermentation. Their enzyme activities were compared with those of the traditional meju that is made in Sunchang Folk Village according to the traditional method. In the meju that were inoculated with selective strains, the aerobic bacteria counts and mold counts exceeded 8 log cfu/g and 6 log cfu/g respectively, which were the highest fermentation values after 2 days. The aerobic bacteria counts were maintained from 2-day to the 12-day fermentation. The mold counts tended to decreased gradually after the 2-day fermentation. The amino-type nitrogen contents reached 430.5-577.5 mg%, which were the highest values after 2-day fermentation. The neutral protease activities of these mejus had the highest levels in the following order: traditional meju, <TEX>$1,258.0{\pm}38.8$</TEX>; AS meju, <TEX>$1,238.3{\pm}38.6$</TEX>; AO meju. <TEX>$1,204.1{\pm}24.1$</TEX>; ASBS meju, <TEX>$1,040.6{\pm}10.6$</TEX>; and AOBS meju, <TEX>$1,033.5{\pm}11.2$</TEX> unit/g. The acidic protease activities of these meju had the highest levels in the following order: AO meju, <TEX>$1,030.1{\pm}19.1$</TEX>, traditional meju, <TEX>$1,007.7{\pm}30.5$</TEX>; AS meju, <TEX>$990.9{\pm}25.0$</TEX>; AOBS meju, <TEX>$910.9{\pm}15.3$</TEX>; and ASBS meju, <TEX>$888.2{\pm}15.7$</TEX> unit/g.