• Journal of the Korean Society of Food Science and Nutrition
• /
• v.15 no.2
• /
• pp.152-157
• /
• 1986

Changes in protein, amino acids composition and protein activity of native Meju were investigated at various time intervals over 6 weeks of fermentation by using, gel filtration, and amino acid analyzer. From the quantitative fractionation of native Meju proteins, albumin content (36.4%) was the highest at 4 weeks. During Meju fermentation, albumin increased gradually but glutelin decreased up to 4 weeks. Globulin and prolamin content did not change substantiantiall. When albumin was fractionated by Sephadex G-200, two main peaks were fractionated and a new peak appeared after 4 weeks. Its molecular weight was extimated to be 66,000 by the gel filtration method. Amino acid composition of albumin in native Meju appeared to be 17 kinds. Glutamic acid content (87.98-317.10) were the highest, followed by aspartic acid and glycine. The proleolytic enzyme activity increased when the native Meju was fermented and marked the maximum value at 4 week.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.11
• /
• pp.1523-1531
• /
• 2012

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.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.23 no.5
• /
• pp.792-798
• /
• 1994

In order to investigate the antioxidant activity of phenolic compounds contained in domestic Meju and Doenjang , the methanolic extract from defatted Meju and Doenjang was fractionated into the phenolic acid and the isoflavone fractions by alumina column and polyamide-6 column chromatography, respectively. Both phenolic acid and isoflavone fractions exhibited an identical antioxidative effect against the oxidation of linoleic acid. GC analysis revealed that the phenolic acid fractio contained vanillic , chlorogenic ,p-coumalic , ferulic, and caffeine acid. The content of caffic acid was greater than 70% in the phenolic acid fraction and the content of vanillic and chlorogenic acids were disappeared during fermentation, and thus, the facts are thought to be reasons for the low antioxidant activity of the phenolic aicd fraction from Doenjang. Similarly, the isoflavone fraction cotained daidzin, glycitin-65-0 glucosider and genistin and their aglycons such as daidzein, glyciten and genistein. The content of daidzin and genistin in Meju dramatically decreased at the early stage of fermentation ,whereas the content of daidzein an dgenistein rather increased ; however, these change in isoflavone contents did not affect the antioxidant activity of isoflavone fractions.

• The Korean Journal of Mycology
• /
• v.51 no.3
• /
• pp.219-227
• /
• 2023

This study was conducted to analyze the distribution and characteristics of fungal species in meju using the traditional method. Fungal distribution in meju was investigated using metagenomic and morphological analyses, based on which Aspergillus flavus/oryzae strains were identified as the dominant fungi in all meju samples, followed by Pichia, Rhizopus and Lichtheimia spp. As A. flavus/oryzae was dominant, we further evaluated the aflatoxin production ability and enzymatic activity of the isolates. Thin-layer chromatography and polymerase chain reaction revealed that the A. flavus/oryzae strains isolated from meju are non-aflatoxigenic fungi. Based on the analyses of amylase and protease activities, strains with high activities of amylase or protease were identified, which are proposed to be used as starters for meju fermentation.

• Applied Biological Chemistry
• /
• v.35 no.4
• /
• pp.286-293
• /
• 1992

This study was investigated on the change of physico-chemical properties at various mixture ratio of improved Meju and Natto during the aging of soybean paste. pH was increased on the improved Meju with increasing the mixture ratio of Natto, but pH was decreased in Korean traditional Meju. Change of nitrogen compound was 3 times higher and aging was faster in increased ratio of Korean traditional Meju than that of improved Meju. Brown color was not changed as compared to the initial stage, however the value of brown color was higher in the Korean traditional Meju than that of other group. In sensory evaluation, the mixture ratio of improved Meju, Korean traditional Meju and Natto (48 : 48 : 5) was the best acceptables.

• Korean Journal of Food Science and Technology
• /
• v.34 no.3
• /
• pp.536-539
• /
• 2002

This study was investigated for the preparation method of meju by three step fermentation. The steamed soybeans were fermented with nisin-producing Lactococcus lactis subsp. lactis IFO12007 to inhibit the growth of odor-producing Bacilli and promote of normal fermentation of meju. The lactie-fermented soybeans were further fermented with Aspergillus oryzae and Bacillus subtilis. The produced meju by this method showed 54%moisture content and pH 7.0, respectively. The three step fermented meju was soaked in 20% (w/v) brine at $25^{\circ}C$ for 90days. After 30 days, the contents of total free amino acids revealed 4,015 mg% which were higher $3{\sim}5$ times than controls. Among the detected free amino acids, the contents of glutamic acid and leucine showed 925 mg% and 380mg%, respectively. Therefore, the new method of producing meju would be an excellent alternative to improve the quality of soybean fermented food, such as doenjang and kanjang.

• Food Science and Biotechnology
• /
• v.17 no.2
• /
• pp.442-445
• /
• 2008

Meju, a major ingredient of doenjang which is a popular Korean traditional fermented soyfood, was manufactured by fermenting steamed soybeans in natural environment in which steamed soy was exposed to airborne microorganism, in particular, fungi. Total isoflavone content was reduced from 1,849 mg/kg of cooked soy to 816 mg/kg of meju at the $90^{th}$ day of fermentation. Total glycosides and aglycones of isoflavones in meju were 1,827 and 22 mg/kg at 0 day and changed into 487 and 329 mg/kg at the 90th day of fermentation, respectively. Meanwhile, the ratio of glycosides to aglycones of isoflavones was not changed during aging of doenjang but remained relatively constant with 592 and 644 mg/kg aglycones at the 0 and $160^{th}$ day, respectively. When cooked soy was fermented with Aspergillus oryzae and Aspergillus flavus, isoflavone profiles were significantly different from each other while A. oryzae caused more extensive metabolism of isoflavones than A. flavus.

• Microbiology and Biotechnology Letters
• /
• v.11 no.3
• /
• pp.241-248
• /
• 1983

Lupin seed was used to make Meju, the fermentation starter for Korean soybean sauce and paste in substitution for soybean and the fermentation characteristics were compared with those of soybean. Mejus were prepared by in-oculating Asp. oryzae on the cooked whole beans. The dried Mejus were used for making fermented bean sauce and paste by mixing with brine and subsequent ripening for 4 weeks. In general the protease activity and amylase activity-during ripening were higher in lupin seed Meju than those of soybean Meju. The increase in protease activity correlated to the increase in $\alpha$-amino nitrogen content of the fermented paste and sauce. The development of dark-brown color of the sauce during ripening faster with lupin seed Meju compared to soybean Meju. In sensory evaluation the flavor score of lupin seed sauce and paste was slightly lower than that of soybean products but the overall quality of fermented lupin seed sauce was acceptable.

• The Korean Journal of Food And Nutrition
• /
• v.31 no.5
• /
• pp.751-759
• /
• 2018

This study was conducted to investigate quality characteristics of red bean gochujang prepared with different ratios of meju for eight weeks. We determined quality characteristics such as pH, moisture content, total microbial flora counts, amino-type nitrogen content, total polypenol content, and antioxidant activity. The pH decreased by fermentation period, whereas total acidity was 0.36~0.39% in the early stage of fermentation, 0.63~1.16% at four weeks of fermentation, and decreased to 0.43~0.65% after the eighth week of fermentation. Moisture content of the control (no red bean, no rice) decreased 62.13% to 50.93%, but in case of the treatment, it slightly decreased. Total cell counts revealed similar tendency at the beginning of fermentation, and at eight weeks of fermentation. In case of lactic acid bacteria, all samples except RB-1.5 (gochujang added meju made of mixing ratio of rice:soybean:red bean (1:2:1.5) slightly increased. Amino nitrogen and total polyphenol of all samples increased in the fermentation period, especially RB-1.5 sample had the highest levels than other samples. By increasing the amount of red bean, DPPH radical scavenging activities increased. In taste sensing analysis, all treat samples except RB-1.5 revealed lower sourness than the control. Also, in case of bitterness, all samples revealed low content than the control. So, by adding red bean, it can enhance taste and function of gochujang.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.41 no.8
• /
• pp.1066-1071
• /
• 2012

In this study we investigated the change in antigenicity and allergenicity of Meju, a traditional Korean soybean product, by fermentation via 3 different microorganisms. The steamed soybeans were fermented with Lactococcus lactis subsp. lactis and/or Aspergillus oryzae and/or Bacillus subtilis. Proteins in soybean were degraded after fermentation. Antigenicity or allergenicity were analysed by immunoblotting and ELISA using soybean protein-specific polyclonal antibodies or soybean allergic patient sera. The best degradation was achieved by three step fermentation using nisin-producing Lactococcus lactis subsp. lactis IFO12007, A. oryzae and B. subtilis. Allergenicity and antigenicity were also starkly reduced after three step fermentation. The three-step fermentation method developed in our lab suggests an excellent alternative to reduce the allergenicity of soybeans.