• Korean Journal of Food Science and Technology
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• v.40 no.6
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• pp.656-660
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• 2008

Fermented soybean foods are an important component of the Korean diet. Eoyukjang is a type of traditional fermented soybean source. Microbial analysis of eoyukjang was conducted during the fermentation period in this study. Microorganisms isolated from eoyukjang were identified by biochemical tests and 16S rDNA sequencing. 17 different microorganisms, including bacteria, yeast, and fungi were detected in eoyukjang during the fermentation period. Even though Aspergillus participated in the early stage of fermentation of eoyukjang, Bacillus species and Saccharomyces cerevisiae were the major microzymes in eoyukjang throughout the maturation period. Eoyukjang is generally consumed after the boiling of the final sample. Therefore, the final sample of eoyukjang was boiled and analyzed. Our results showed that no vegetative microorganisms survived under the boiling conditions for eoyukjang. Fermented soybean products in the domestic market were also assessed for comparison with the results from eoyukjang. The total cell number of kanjang (soy sauce) samples was between 0 to 42 CFU/mL. The isolated microorganisms were identified as Bacillus species. All Bacillus isolates were not found to harbor the three enterotoxin-producing and emetic toxin-producing genes.

• Food Science and Biotechnology
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• v.18 no.1
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• pp.48-52
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• 2009

Eoyukjang is a traditional Korean sauce made of cooked soypaste or meju supplemented with fish and meats at least 1 year of fermentation period. Eoyukjang was recovered according to the traditional method and stored under the ground in a pot without plastic packaging (13G: 13 month fermentation under the ground) or in an incubator wrapped with plastic packaging (6I, 12I, and 18I: 6, 12, and 18 month fermentation, respectively). Distribution of isoflavones and fatty acids were monitored by high performance liquid chromatography (HPLC) and gas chromatography (GC), respectively. Total isoflavones in 13G, 6I, 12I, and 18I were 3.792, 0.387, 0.460, and $0.510{\mu}mol/g$, respectively. Samples of 13G had at least 8.24 times higher isoflavone contents than samples from 12I. Aglycones were the major isoflavones in eoyukjang and were found more than 92% in 13G and 39-63% in incubated samples. In fatty acid analysis, the ratios of unsaturated to saturated fatty acids from 13G were higher than those from 6I, 12I, and 18I. Traditional fermentation methods using a pot may allow more migration of air and moisture than samples wrapped with plastic packaging, which caused the difference in the distribution of isoflavones and fatty acids.

• Korean Journal of Food Science and Technology
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• v.40 no.3
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• pp.251-256
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• 2008

Eoyukjang is a traditional sauce-type of Korean food that is similar to a soybean sauce made from fermented soybeans, and it is produced from a fermented mixture of sea foods, meats, and meju (soybean paste). This study examined periodical changes in the enzymatic activities of ${\alpha}$-amylase, esterase, ${\beta}$-glucosidase, protease, lipase, and lipoxygenase within the culture broth and solids of eoyukjang during 1 year of fermentation. The eoyukjang solids had 234-532% higher protein content than the culture broth. The specific activities of ${\alpha}$-amylase, esterase, ${\beta}$-glucosidase, and protease increased in both the culture broth and solids. Particularly, in the culture broth, ${\alpha}$-amylase, esterase, ${\beta}$-glucosidase, and protease activities rapidly increased (3- to 8-fold) until 10 months of fermentation, and then drastically decreased. However, the activities of lipase and lipoxygenase in both the culture broth and solids were less than 0.05 unit/mg of protein, respectively, throughout fermentation; thus, their activity levels were low and changed little over the 12 months. Overall, while the solids had higher protein content than the culture broth, the broth had greater enzyme activity levels during eoyukjang preparation.

• Microbiology and Biotechnology Letters
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• v.47 no.2
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• pp.201-210
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• 2019

Biotransformation of ginsenosides by microorganisms alters the absorption and bioavailability of ginseng as a medicinal herb. In this study, we isolated two kinds of fermenting microorganisms from Eoyukjang, which is a traditional Korean fermented food made from soybean. Next, we identified and detected their ability to convert major ginsenosides to compound K. The two microorganisms, referred to as R2-6 and R2-15, had 100% similarity with Lactobacillus plantarum subsp. plantarum ATCC $14917^T$ and Lactobacillus rhamnosus JCM $1136^T$, respectively. The optimal pH and growth temperature of the isolates were determined to be pH 6-7 and $30^{\circ}C$. After fermentation for 30 days, the major ginsenosides in the mountain-cultivated ginseng were transformed to the highly bioactive ginsenoside, compound K, in the final product.