• The Korean Journal of Food And Nutrition
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• v.12 no.3
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• pp.226-232
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• 1999

To evaluate the characteristics of modified nuruk made by inoculation and cultivation of Rhizopus jap-onicus T2, Aspergillus oryzae L2 and hansenula sp. BC26 three different Takju mashes were made with modified Nuruk commercial Nuruk and rice koji and the changes in microorganisms and major compon-ents of mashes were investigated uring brewing. The numbers of yeast kept higher in the mash of mod-ified Nuruk or rice koji. The numbers of lactic acid bacteria were high in mash of commercial Nuruk but those were not in mash of modified Nuruk or rice koji. all mashes showed stable pH in a day and the pH kept higher in mash of modified Nuruk than in that of commer-cial Nuruk or rice koji. Increase in the content of total acid was moderate in mash of modified Nuruk or rice koji but it was too much in that of commercial Nuruk. increase in the content of amino acid was much highr in mash of modified Nuruk or commercial Nuruk than in that of rice koji. Increase in the content of alcohol was more rapid in mash of modified nuruk or rice koji than in that of commercial Nur-uk. The content of reducing sugar kept highter in mash of commercial Nuruk or modified Nuruk than in that of rice koji. A small amount of modified Nuruk accomplished favorable fermentation showing nor-mal patterns in microbiological and physicochemical changes during brewing.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.4
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• pp.789-799
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• 1998

Literatures on microorganisms of traditional Korean nuruk published since 1945 were reviewed in this paper. Traditional Korean nuruk consists of raw barley and various grains. Traditional Korean nuruk consists of unbolied raw barely and various grains. They are ground to paste and moistened, and then naturally inoculated by airborne microorganisms. Therefore, many kinds of microorganisms such as fungi, yeast, and bacteria grwo in nuruk. Since 1945, new 14 species of Aspergillus and 9 species of Penicillium have been identified from traditional Korean nuruk. Total number of fungal species identified so far is now up to 38 species among 12 different genus. Among newly isolated fungal species, Aspergillus penicilloides and Penicillium, expansum showed not only high production rate of acid and amylase but also extreme stability of the enzyme at room temperature for 3 months. As examples of newly isolated yeast species, there are 5 species of Candida, 4 species of Hansenula, 1 species of Pichia and 1 species of Schizosaccharomyces. Total number of yeast species isolated so far is up to 18 species from different 8 genus. Newly isolated bacteria, were Bacillus pumilus, Lactobacillus casei and Leuconostoc mesenteroides.

• Journal of the East Asian Society of Dietary Life
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• v.21 no.6
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• pp.897-904
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• 2011

For set up the processing method of Byeo-Nuruk, we investigated the quality characteristics of Byeo-Nuruk according to the mixture ratio of rice and wheat, as well as the addition rate of moisture. After 12 hours of incubation, the temperature of Nuruk increased dramatically and reached a maxium temperature at 36 hours. After 36 hours, the temperature decreased gradually and was maintained at about $31{\sim}38^{\circ}C$. The ranges of pH and titratable acidity of Byeo-Nuruk were 4.85 to 7.42 and 1.0 to 2.3, respectively. A higher content of wheat ratio in Byeo-Nuruk, was associated with higher enzyme activities of ${\alpha}$-amylase, glucoamylase, and acidic-protease. Further, at a 70% wheat ratio, a 25% addition rate of moisture showed the highest enzyme activity. In the mixture ratio between rice and wheat, the 50:50 and 30:70 treatments contained the highest levels of microorganisms.

• Journal of the East Asian Society of Dietary Life
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• v.22 no.1
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• pp.103-108
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• 2012

Nuruk is a fermented ingredient used for production of traditional Korean rice wine. In this study, quality characteristics of mixed-grain nuruk was made by brewing with different fungal strains was analyzed. Quality elements including enzyme activity and organic acids constituents were measured. The fermentation time of the nuruk did not make a significant difference in terms of its pH, but the acidity and amino acid content for nuruk made from a mixture of two fungal strains was higher than that seen with a single fungal strain. Overall, the enzyme activity for two fungal strain nuruk was higher than that observed for single fungal strain nuruk, with ${\alpha}$-amylase and acidic protease activity in the mixed strain nuruk observed to be more than twice that of the single strain. The major organic acids observed in the manufactured nuruk were identified as acetic, citric, formic, fumaric, lactic, malic and oxalic acids. The total amount of organic acids contained in the nuruk made with the two fungal strain was (2,116.3 mg%). The fungal strains used were A. kawachii SC60 nuruk (1,608.5 mg%) and A. oryzae RIB1353 nuruk (1,146.7 mg%).

• Korean Journal of Food Science and Technology
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• v.34 no.2
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• pp.296-302
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• 2002

Quality characteristics of mash of takju prepared by wheat flour nuruks (conventional and improved style) were investigated during fermentation. Those were cultured with wild microorganism on whole and crushed wheat (wheat nuruk), wheat flour and mixture of rice and wheat flour, and nuruk cultured with Aspergillus oryzae on wheat flour. Ethanol content reached maximum of 10.6-17.4% after 14 days of fermentation. And the ethanol contents of takju were high in order of wheat nuruk, wheat flour nuruk, Aspergillus oryzae nuruk and mixture of wheat flour and rice nuruk. No difference of pH was among the treatments while the wheat flour nuruk cultured with wild microorganisms contained higher amounts of acids than the others. The amount of total sugars ranged from 16.22-17.74% on the starting day of fermentation, and decreased to 4.28-6.10% after 14 days. The amount of total sugars in mashes brewed with wheat flour nuruk cultured with Aspergillus oryzae was measured to be highest at the beginning stage of fermentation. Afterwards no difference was found among the types of nuruks. Glucose was in the range of 2,735-7,842 mg% at initial period of fermentation, afterwards it was rapidly decreased. The total amounts of free sugar for control and the wheat flour nuruk was higher than other treatments. The total amounts of organic acids were the highest in wheat nuruk to 690-2,241 mg% and the contents of lactic acid and succinic acid were high in mixed rice nuruk to 183-1,293 mg%. The contents of lactic acid and succinic acid were higher than those of the other kinds of organic acids in takju.

• Korean Journal of Food Science and Technology
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• v.22 no.2
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• pp.134-139
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• 1990

A strain of Nuruk yeast No. IS (NY-15) which produced high activity of ${\beta}-galactosidase$ was isolated from Nuruk, and the crude enzyme was prepared by whey permeate culture of the microorganism. The crude enzyme was purified 40-fold with a 7.7% yield by acetone and ammonium sulfate fractionational precipitation, and chromatography on DEAE-cellulose, DEAE-Sephadex A-50 and Agarose-PAPT. Purified ${\beta}-galactosidase$ from Nuruk yeast showed two types of subunit patterns; a slow moving band and a fast moving deeply stained band, both anode·migrating at pH 7.5. The molecular weight of the former was estimated to be about 130,000 and that of the latter was 96,000 by SDS-polyacrylamide gel electrophoresis. The optimum pH of the enzyme activity was 7.5 and maximum activity appeared at $40^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.4
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• pp.577-583
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• 2014

In this study, we evaluated fermentation characteristics of microorganism with antimicrobial activity in makgeolli made from various kinds of koji and nuruk during fermentation. The pH of nuruk groups decreased compared to the koji groups after 3 days of fermentation. Acidity and alcohol contents of nuruk groups significantly increased compared to the koji groups. The total sugar contents of the koji groups were significantly higher than those of the nuruk groups after 15 days of fermentation. Sensory scores of koji groups (DKB) were higher than those of other samples. Antimicrobial activities of nuruk group (GND and ANF) against Salmonella enterica, Bacillus subtilis, Escherichia coli, and Bacillus cereus were significantly higher compared to the koji group. ST-1, isolated from (Geumjeonggu nuruk D), showed the highest antimicrobial activity and was identified as Paenibacillus polymyxa strain RCP6 based on 16S rRNA sequencing. Our result suggest that Paenibacillus polymyxa from nuruk group produces a bacteriocin-like substrate with antimicrobial activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.1
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• pp.170-179
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• 1996

누룩은 생소맥을 조분쇄하여 물로 혼합시켜 자연적으로 공지중의 여러 종류의 미생물을 배양시켜 만들었다. 그러므로 누룩에서는 많은 종류의 사상균, 호모와 세균이 증식하였다. 누룩의 당화력은 원료 생소맥의 당화력과 대부분의 사상균의 당화력과 알붕의 세균성 당화력에 기인하여, 발효력은 누룩효모와 극소수의 사상균애 의하여 이루어지고 있다. 1945년 이전까지 누룩으로부터 12속 59종의 사상균이, 8속 29종의 효모와 4속 16종의 세균이 분리 되었다. 누룩사상균은 Aspergillus 속이 주종을 이루었고 Rhizopus속, Absidia속, Nucor속의 순으로 분포하고 있었고, Aspergillus속과 Rhizopus속은 중요한 누룩 당화균으로 작용하였다. 누룩의 대표적 효모는 Saccharomyces cerevisiae 이며 , 이균이 알코올 발효에 가장 큰 역할을 담당하며, Saccharomyces cerevisiae도 전통 민속주의 탁주와 약주의 발효역에 깊이관여한다고 사료된다. 누룩 중에 증식하는 세균은 양조학상 특별한 역할을 담당하지않지만 Bacillus 속 과 젖산세균이 많이 분리되었으며, 젖산세균은 담금초기에 pH의 안정화에 기여할 수 있다고 추측할 수 있다.

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.182-187
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• 2004

Strain NR $15-1^T$ isolated from traditional Korean Nuruk is described as a new species and named as Aspergillus coreanus NR $15-1^T$ sp. novo Strain NR $15-1^T$ grew rapidly to form yellow-green colonies whose surfaces were velvety on Czapek solution agar. Conidial heads were yellow to light and elliptical, whereas the conidiophore was colorless and typically long. In addition, vesicles were from flask-shaped to globose, and sterigmata are uniseriate. Conidia were spherical and deep yellow-green, and their surfaces were lightly roughened. The G＋C content of strain NR $15-1^T$ was 51 mol% and strain NR $15-1^T$contained a dihydrogenated ubiquinone with Q9 (94.9%) as a major quinone. The nucleotide sequences of strain NR $15-1^T$ in the two Internal Transcribed Spacers (ITS 1 and 2) and 5.8S rDNA showed highest similarity when compared with that of A. tubingensis and A. phoenicis NRRL $365^T$. However, based on morphological and chemotaxonomic characteristics, this strain was different from A. tubingensis and A. phoenicis NRRL $365^T$. On the basis of the data presented, it is proposed that strain NR $15-1^T$ should be placed in the genus Aspergillus as a new species, Aspergillus coreanus sp. novo Therefore, the type strain of the new species is strain NR $15-1^T$ (=KCTC 18075P^T,=KCCM 80006^T$.

• Korean Journal of Food Science and Technology
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• v.44 no.6
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• pp.728-735
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• 2012

Makgeolli is the oldest Korean traditional wine made from rice, and contains 6-8% alcohol. Also, nuruk is traditionally prepared by exposing moistened ground wheat or rice to the air, and there contained airborne microorganism. In this study, purple sweet potato (PSP) was used as a raw material in the rice nuruk- and makgeolli-making processes. PSP rice nuruk (RN) was made with rice and 0-10% (w/w) PSP, and the characteristics of makgeolli were studied during fermentation. The pH during fermentation decreased from 4.27 (0% PSP-RN), 4.59 (2.5%), 4.50 (5.0%), 4.46 (7.5%), and 4.43 (10.0%) of initial fermentation day to 4.12, 3.82, 3.67, 3.71, and 3.66, respectively, at day 7. The sugar contents increased from $0.4^{\circ}Bx$ of the initial day to $8.0-8.4^{\circ}Bx$, and the levels of alcohol increased to 13.0% (0% PSP-RN), 13.2% (2.5%), 12.8% (5.0, 7.5, and 10.0%) by day 7, respectively. In addition, the contents of soluble anthocyanins and phenolics increased from 0.001-0.121 and 0.2-0.27 g/L on the initial fermentation day to 0.002-0.166 and 1.65-1.87 g/L, corresponding to increases in levels of antioxidant activities of 20-50%, respectively.