• Food Science and Biotechnology
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• 제15권4호
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• pp.643-646
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• 2006

Cheonggukjang, a popular Korean traditional fermented soyfood, was manufactured by fermenting steamed soybeans in a temperature-controlled room by traditional methods in which steamed soy was exposed to rice straw naturally rich in Bacillus species. B. subtilus and B. licheniformis were found to be the major microorganisms present in cheonggukjang made by the traditional method. We analyzed the composition of 12 kinds of isoflavones and their glycosides present in cheonggukjang collected at various fermentation times. Total isoflavone content in raw soybeans was 2,867 mg/kg and this decreased by about 50% during cooking prior to cheonggukjang preparation. However, total isoflavone content changed slightly during 45 hr of fermentation. Total content of isoflavone glycosides, consisting mainly of daidzin, glycitein, and genistin, decreased by about 40% during 45 hr of fermenting cooked soybeans. The contents of tree isoflavones including daidzein, glycitein, and genistein showed a dramatic increase during fermentation in cheonggukjang preparation, with a 2.9-, 54.0-, and 20.6-fold increase in concentration, respectively, by the end of fermentation (45 hr). In conclusion, short-term fermentation of cooked soybeans with Bacillus species caused conspicuous changes in the composition of isoflavone derivatives, and its implication in terms of health benefits deserves further study.

• Preventive Nutrition and Food Science
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• 제12권4호
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• pp.234-241
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• 2007

A physicochemical assessment of Doenjang (traditional fermented soyfood) prepared with Korean black soybeans (Glycine max) was carried out. The T-N rate increased slowly during storage up to 120 days and the A-N rate increased up to 80 days of ripening and then decreased slightly. The caseinolytic activity increased slowly during storage up to 80 days and then decreased after 80 days. In addition, the fibrinolytic and ${\beta}-glucosidase$ activities increased up to 80 and 30 days and then decreased. Genistin and daidzin concentrations gradually decreased with increased fermentation time. However, genistein and daidzein slowly increased with fermentation time. Genistein and daidzein reached maximum concentrations (316.8 and $305.2{\mu}g/g$, respectively) and plateaued thereafter. The anthocyanins increased greatly during fermentation up to 50 days and then remained constant between 50 and 90 days. Polyphenol contents showed a slight increase up to 80 days and then slowly decreased. The DPPH and ABTS radical scavenging activities increased linearly during storage up to 50 days, reached about 28.9% and 2.17 mg/g, respectively, and then slowly decreased. At 20 days of fermentation, macrophage-stimulating activity of the extract showed a maximum activity.

• Food Science and Biotechnology
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• 제17권2호
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• pp.442-445
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• 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.

• Journal of Microbiology and Biotechnology
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• 제25권1호
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• pp.89-97
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• 2015

Bacillus subtilis HK176 with high fibrinolytic activity was isolated from cheonggukjang, a Korean fermented soyfood. A gene, aprE176, encoding the major fibrinolytic enzyme was cloned from B. subtilis HK176 and overexpressed in E. coli BL21(DE3) using plasmid pET26b(+). The specific activity of purified AprE176 was 216.8 ± 5.4 plasmin unit/mg protein and the optimum pH and temperature were pH 8.0 and 40℃, respectively. Error-prone PCR was performed for aprE176, and the PCR products were introduced into E. coli BL21(DE3) after ligation with pET26b(+). Mutants showing enhanced fibrinolytic activities were screened first using skim-milk plates and then fibrin plates. Among the mutants, M179 showed the highest activity on a fibrin plate and it had one amino acid substitution (A176T). The specific activity of M179 was 2.2-fold higher than that of the wild-type enzyme, but the catalytic efficiency (k_cat/K_m) of M179 was not different from the wild-type enzyme owing to reduced substrate affinity. Interestingly, M179 showed increased thermostability. M179 retained 36% of activity after 5 h at 45℃, whereas AprE176 retained only 11%. Molecular modeling analysis suggested that the 176^th residue of M179, threonine, was located near the cation-binding site compared with the wild type. This probably caused tight binding of M179 with Ca²⁺, whichincreased the thermostability of M179.

• 한국식품과학회지
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• 제34권3호
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• pp.365-369
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• 2002

본 연구에서는 콩과 콩 가공식품의 isoflavones 함량에 대한 기초 자료 구축을 위해 수원 작물시험장에서 분양받은 흰콩 41종, 검정콩 5종의 국산 콩 46품종과 두부, 된장 등 콩 가공식품의 isoflavones 함량을 분석하였다. 각 시료의 isoflavones 함량 -daidzeine과 genistein 유도체의 합은 건조 중량 1g당 함량으로 나타내었다. 46품종의 콩을 분석한 결과 isoflavones 함량은 $309{\sim}1610\;{\mu}g/g$의 범위로, 평균 $809\;{\mu}g/g$을 함유하고 있었다. 이 중 신팔달 2호의 isoflavones 함량이 가장 높았고 다원콩의 함량이 가장 낮았다. 청국장의 isoflavones 함량은 $1045\;{\mu}g/g$, miso는 $1067\;{\mu}g/g$으로 된장의 $781{\mu}g/g$보다 높았다. 두부, 연두부, 순두부 및 유부의 isoflavones 함량은 각각 $650\;{\mu}g/g$, $895\;{\mu}g/g$, $685\;{\mu}g/g$, $616\;{\mu}g/g$이었다.

• 한국식품과학회지
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• 제32권4호
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• pp.936-941
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• 2000

검정콩을 이용하여 제조된 청국장의 기능적 특성을 평가하기 위하여 검정콩 청국장의 메탄올 추출물에 대한 몇가지 기초적인 생리활성과 발효중 phytoestrogen화합물(daidzein, genistein)의 함량변화를 조사하였다. 대두 청국장의 추출물은 대부분의 시험균주에 대하여 거의 항균활성이 없거나 약하게 나타났으나, 검정콩 청국장의 추출물은 시험균주 모두에서 항균활성을 나타내었다. 특히, 소립 검정콩의 청국장 추출물의 항균활성이 대립 검정콩보다 강하였다. 대립 및 소립 검정콩 청국장의 수소공여능은 각각 76.4및 75.5%로서 대두 청국장의 67.3%에 비하여 더 높게 나타났다. 또한 아질산염 소거능은 각 청국장 추출물에서 대조구에 비하여 모두 90%이상을 나타내었다. Linoleic acid에 대한 과산화물 및 흰쥐의 간 지질에 대한 TBA의 수치는 청국장의 추출물을 첨가한 시험구가 첨가하지 않은 대조구에 비하여 낮았으며, 그 항산화 효과는 소립 검정콩, 대립 검정콩 및 대두 청국장의 추출물 순이었다. Daidzein 및 genistein의 함량은 청국장 발효중 점진적으로 증가하였으며, 대두 청국장에 비하여 검정콩 청국장의 함량이 훨씬 높았고, 대립 검정콩이 소립 검정콩으로 제조한 청국장의 함량보다 높게 나타났다. 또한 genistein 함량은 대체로 daidzein 함량의 2배정도였다.