• Korean Journal of Food Science and Technology
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• v.43 no.5
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• pp.570-576
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• 2011

The effect of nuruks and crude amylolytic enzyme on free amino acid and volatile components of brown rice vinegar prepared by static cultures was investigated. Five groups consisted of AV (100% nuruk without crude amylolytic enzyme), BV (75% nuruk; 25% crude amylolytic enzyme), CV (50% nuruk; 50% crude amylolytic enzyme), DV (25% nuruk; 75% crude amylolytic enzyme) and EV (100% crude amylolytic enzyme without nuruk). Free amino acid content in AV vinegar (132.06 mg%) was lower than the others (184.56-191.22 mg%). Acetic acid, 3-methyl butyl acetate, acetoin and isoamyl alcohol were major volatile components as analyzed using gas chromatography-mass spectrometry after headspace solid-phase microextraction. Acetic acid in AV and EV samples represented 67.56% and 55.53% of total GC peak area, respectively. E-nose provided different patterns in each case showing variation in sensory properties.

• Food Science and Preservation
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• v.12 no.2
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• pp.190-194
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• 2005

This study investigated the characteristics of honey wine, which was fermented by Saccaromyces sake, Saccharomyces bayanus and Nuruk. For alcohol fermentation of the diluting solution, mixtures of S. sake and Nuruk, and Nuruk and S. bayanus resulted the excellent fermentation. These conditions also produced a higher alcohol content than that from the single yeast Strain. The values of pH and acidity of honey wine showed little changes during the fermentation processes. In the case of the mixture of Nuruk and yeast, the content of reducing sugar during the fermentation processes decreased rapidly, but the content of alcohol increased. The soluble solids were $7.5\~8.1\;^{\circ}Brix$ after the fermentation period of 6 days, and the alcohol contents were represented $12.5\~13.1\%$, from the mixture of Nuruk and yeast. In addition, the sensory evaluation of honey wine with the mixture of Nuruk and yeast showed more effective results than that of the single yeast bacillus.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.340-347
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• 2019

This study investigated the brewing properties of rice beer made with yeast isolated from traditional whole wheat nuruk. The experimental method was followed by alcohol fermentation and quality analysis for six months after separating the yeast from nuruk. The yeasts isolated from traditional nuruk showed normal fermentation characteristics, like those of commercial yeast, in terms of alcohol production capability, sugar content, and pH reducing power. Especially, the yeast (KCCM 301) isolated from whole wheat nuruk showed higher contents of glycogen and trehalose than that of commercial yeast, and so KCCM 301 yeast has excellent yeast vitality. Meanwhile, the yeast (KCCM 90301) isolated from traditional Nuruk produced significantly higher alcohol and ester contents than that of commercial yeast. This has a positive effect for supplementing the taste and aroma of rice beer. In conclusion, the yeasts isolated from whole wheat nuruk showed the general alcohol fermentation pattern and aroma content of rice beer. These yeasts seem to be effective in strengthening the flavor of rice beer.

• Korean Journal of Food Science and Technology
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• v.46 no.2
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• pp.153-164
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• 2014

Five takju prepared using four types of nuruk (a traditional Korean fermentation starter made of malted wheat; non-cooked, naturally inoculated) labeled SH, SS, JJ, and SJ, and one type of koji (cooked, inoculated with an inoculum) labeled MN, were compared. Titratable acidity, pH, sugars, ethanol, amino acids, organic acids, and microbial changes in samples were measured, and the sensory properties were evaluated. Titratable acidity, alcohol, and organic acid content increased as sugar contents decreased. The overall ethanol concentration of all takju increased over time, reaching a maximum of 13.08-14.96% (w/v) at 7-21 days. The total amino acid contents of takju prepared with nuruk, except for one (SJ), were higher than the takju prepared with koji (MN). Lactic acid bacteria were also isolated from the starters. Sequence analysis of 16S rRNA genes (500 - 600 bp) of 223 isolates revealed that the major strains were in the genera of Leuconostoc, Weissella, Pediococcus, and Lactobacillus.

• Applied Biological Chemistry
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• v.45 no.3
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• pp.138-144
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• 2002

In order to improve the quality of foxtail millet wine, zymological properties by isolated strains from Nuruk were investigated. Saccharomyces sp Y5-1 as brewing yeast, Aspergillus sp. M6-3, Aspergillus awamori 6970, and Aspengillus usamii mut. shirousamii 6959 (KCTC) as saccharifying molds were used, respectively. Acid content, soluble solids, color (b) and alcohol contents were increased during fermentation. Ethanol concentration of millet wine made with Nuruk by Aspergillus awamori 6970 and Aspergillus usamii mut. shirousamii 6959 were higher than the other, 10.6 and 10.1% respectively. Citric acid was only detected on $1{\sim}2$ day starting fermentation. Oxalic acid, lactic acid and acetic acid of millet wine were high in the wine made of Nuruk by Aspergillus usamii mot. shirousamii 6959, Aspergillus awamori 6970 and traditional Nuruk, respectively. During fermentation, glucose and xylose was higher than the others. Xylose was increased, but most of other sugar were decreased during fermentation. Acetone, ethyl acetate, methanol, ethanol, n-propanol, iso-buthanol and iso-amyl alcohol were detected In the wine made with Nuruk by Aspergillus awamori and Aspergillus usamii mut. shirousamii, iso-imyl alcohol and ethanol were high. On sensory evaluation, the wine made with Nuruk by Aspergillus usamii mut. shirousamii was the best on color and taste.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.1
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• pp.76-82
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• 2009

Wheat is the most widely cultivated cereal and an important source of dietary protein worldwide. Wheat allergy, defined as an adverse immunologic reaction to wheat, encompasses a broad spectrum of disorders with different pathomechanisms and clinical manifestation. The Nuruk, a traditional Korean Koji for brewing, was made with wheat flour and fermenting microbes such as bacteria, yeast and mold. The strains grown on Nuruk secrete various enzymes as amylase and protease. By the activation of such enzymes, starch and proteins in Nuruk are hydrolyzed to sugar and amino acid. Therefore, it is supposed to reduce allergic proteins in wheat. To study quality properties and degradation degree of allergenicity in Nuruk by fermentation, we investigated the changes of general ingredients and allergenicity in Nuruk during fermentation. Moisture contents was decreased from 24.2% to 13.6% during fermentation. Crude lipid and protein contents were gradually increased during fermentation. After 15 days of fermentation, reducing sugar and total sugar contents were reached its maximum level, and they were 27.45% and 39.00%, respectively. Acid and neutral protease activity were significantly increased during fermentation, but alkaline protease activity was not detected. ${\alpha}$-amylase activity was gradually increased and showed maximum level about 2,833.00 U/g after 15 days of fermentation. Glucoamylase activity was the highest level about 497.9 U/g after 10 days of fermentation. The increase of these proteolytic and saccharogenic enzyme activities will provide efficient condition for production of rice wine. Also, protein fractions were isolated from Nuruk, and degradation of these proteins during fermentation were confirmed by SDS-PAGE. IgE immunoblotting using patient's sera with wheat allergy was performed to confirm allergenic protein in Nuruk. These results as fermentation of Nuruk will provide a useful tool for developing safer wheat products to prevent wheat allergy.

• The Korean Journal of Mycology
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• v.30 no.1
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• pp.61-65
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• 2002

The objectives of this study were to find the nuruk fungal isolate for Korean traditional rice wine and to compare the tastes of rice wines made with its single inoculum. The fungal isolates including the species of Absidia, Mucor, Rhizopus and Aspergillus were used for Korean traditional rice-wine production. The four species were cultured and measured for productions of amylase under various water contents. The four different species tested were different in their growth under the rice cereals with different moisture contents; the species of Absidia and Rhizopus grew better compared to the other species under the lower moisture conditions. The tastes and alcohol concentrations of the rice-wines made with each different inoculum were compared with those of commercial rice wines made with traditional method. As a result, it was speculated that the traditional rice wines were made with nuruk, which is mainly composed of Zygomycetous fungi, such as Absidia, Mucor, and Rhzopus. Also, it was strongly suggested that the traditional nuruk might not be a source of amylase, but a source of fungal inoculum.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.10
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• pp.1338-1345
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• 2012

This study investigated the antioxidant activities, whitening effects, and antimicrobial activities of fractions from Pleurospermum kamtschaticumin extract. Total polyphenolic contents of fractions from Pleurospermum kamtschaticumin extract were 116.44~382.73 mg/g GAE (gallic acid equivalent), with the highest value in the ethyl acetate fraction. Fractions of Pleurospermum kamtschaticumin showed the highest DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity ($IC_{50}$=0.04 mg/mL) and ABTS radical scavenging activity (98.86% at 0.5 mg/mL), which was similar to ascorbic acid. Further, reducing power and FRAP activity were significantly high in the ethyl acetate and n-butanol fractions. The ethyl acetate and n-butanol fractions showed significantly high SOD-like activities (1 mg/mL, 86.93%, and 78.23%, respectively) compared to other fractions. Tyrosinase inhibition activities of the n-butanol fraction and 80% ethanol extract were 43.52% and 41.64%, respectively. Antimicrobial activity against Escherichia coli was only observed in the chloroform fraction (16.7 mm in 0.5 mg/disc). These results suggest that fractions from Pleurospermum kamtschaticumin extract show comparatively high antioxidant activity and thus could be used as a food additive or cosmeceutical ingredient.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.7
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• pp.848-856
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• 2017

This study aimed to investigate the effect of rice nuruk prepared from rice with different degrees of milling (0, 10, 30, 50, and 70%) on physicochemical qualities of yakju. The results indicated significant differences in the qualities of yakju prepared using rice nuruk from rice with different degrees of milling. Specially, pH, amino acidity, brownness, b value, and color difference were significantly reduced as the degrees of milling increased, whereas contents of alcohol and volatile acid, reducing sugar, and L value were increased. Malic acid, succinic acid, and lactic acid were the main organic acids in yakju, and there were significant differences among the treatments in malic acid, lactic acid. However, there was no tendency according to different degrees of milling. In addition, contents of total free amino acids and nitrogen compounds showed no tendency according to degrees of milling, whereas the content of aspartic acid showed a tendency to decrease significantly. The content of 2-phenyl alcohol in the volatile flavor components showed a tendency to increase significantly with higher degree of milling of rice nuruk, whereas contents of n-propanol and iso-amyl alcohol tended to decrease significantly.

• Microbiology and Biotechnology Letters
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• v.38 no.4
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• pp.373-378
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• 2010

Studies on standardization and quality upgrade of nuruk which is a basic component in brewing are required to increase the quality level of Korean traditional rice wines and to develop the technology for practical use of it. It is important to isolate best strains, to improve the properties and effectively preserve them for brewing industry. In this study, 16 commercial nuruk samples were obtained from the commercial markets located in Chungcheong areas in Korea. 174 fungal strains were isolated from the samples on DG18 medium using a dilution plating method and then screened for enzyme activity and acid production. The active strains were identified based on the morphological characteristics and ITS sequence analysis. Out of 174 strains, 12 strains showed high amylase activity. Especially, Rhizopus sp. CN084, CN174, Aspergillus sp. CN161 and Mycocladus sp. CN042 showed high saccharogenic power and dextrinogenic enzyme activity on cooked wheat bran medium. On the other hand, Aspergillus sp. CN010, CN161, Rhizopus sp. CN105, CN168 and Rhizomucor sp. CN088 produced high acid production on the same medium. Our results showed that the active strains may be used as microbial sources for nuruk starter with good quality in brewing.