• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.1
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• pp.78-89
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• 1994

To evaluate of quality of Yakju brewed with different types of fermenters(Nuruk) and brewed by a method described in Sallymkyungjae, blucoamylase and protease and protease activities of Nuruk were measured, and proximate composition , coloring degree, acetaldehyde , alcohol , , fusel oils , amino acid content , mineral content and sugar composition of Yakju samples were also determined. It was foung that the lower the pH, the lower the glucoamylase acitvity in Nuruk samples A to E . In A, B, D and H, protease activity washigher at ph 5.5 than at pH 5.0 . Yakju sampels 1 to 5 during fermentation , total acidity and amino acid content were high at the first step and were getting lower gradually at the second step. In Yakju samples 6 to 11 , ethanol content was high in 6b, 7b, 8a, 8b and 11b. At the second step, residual sugar content was getting higher gradually in 7 a, 11 a and 11b. The coloring degree of Yakju wasinfluenced by not only color of Nuruk but also Fe content in Yakju . Of the Yakju examined , only 9a and 9b contained acetaldehyde in trace amounts. Thanol content was the highest in 8a and 8b. Fusel oil content was high in 8a and 8b. In samples 6 to 9 , aspartic acid content was higher in treatment a than treatment a than treatment b, but tyrosine , histidine and proline contents were higher in treatment a than treatment b. The levels of frucose, melibiose, sorbitol, and arabinose in Yakju brewed from unsteamed rice were higher than in Yakju brewed from steamed rice. K content was the lowest in 9a and 9b. Na content was higher in treatment a than in treatment a than in treatment b. In only 6a, Ca/P ratio was more than one.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.5
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• pp.620-628
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• 2013

In this study, the condition for preventing abnormal fermentation was set by heating the nuruk extract, such that glycosyl enzymes maintain its activity and unnecessary microbes are removed. The total colony of microbes in the heated nuruk extract was highest in number at $25^{\circ}C$ and began to reduce at 50, $60^{\circ}C$ and sharply reduced over $70^{\circ}C$. Saccharogenic power (SP), glucoamylase and acidic protease activities were highest at $50^{\circ}C$, 10, 20, 30min and ${\alpha}$-amylase activity was lower at $50^{\circ}C$ than at $25^{\circ}C$. In the pHs of the nuruk extract, as the heat temperature became higher and treatment time was longer, the pHs were reduced significantly. The total acidities of heat treatments at 50, $60^{\circ}C$ were lower by 0.2% than at $25^{\circ}C$, where as the 70, $80^{\circ}C$ treatments showed a sharp rise from the early stage of fermentation. Soluble solids showed the same aspects with the glycosyl enzymes cases. In reducing sugar, 25, $50^{\circ}C$ treatments were sharply increased from the first day of fermentation while $60^{\circ}C$ treatments began to rise from second day 70, $80^{\circ}C$ were slightly increased after the fourth day. The normally alcohol fermented treatments were 25, 50 and $60^{\circ}C$ 30min. The $70^{\circ}C$ treatments almost did not alcohol fermentation. In the preference tests, taste and total acceptability were high at 25, $50^{\circ}C$ treatments. These results suggest that makgeolli using heat treated nuruk extract also has good taste as well as did not.

• 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.

• 한국균학회소식:학술대회논문집
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• 2015.11a
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• pp.11-11
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• 2015

A total of sixty-six samples of Nuruk, a fermention starter used to make the Korean traditional rice wine, Makgeolli, were collected from central and southern regions of Korea in 2013 and 2014. We classified two groups of the Nuruk samples, "commercial" and "home-made", according to the manufacturing procedure and purpose of use. Commercial Nuruks were made in a controlled environment where the temperature and humidity are fixed and the final product is supplied to Makgeolli manufacturers. Home-made Nuruks were made under uncontrolled conditions in the naturally opened environment and were intended for use in the production of small amounts of home-brewed Makgeolli. We obtained more than five hundred isolates including filamentous fungi and yeasts from the Nuruk samples followed by identification of fungal species. Also we stored glycerol stocks of each single isolate at $-70^{\circ}C$. We identified the species of each isolate based on the sequences of ITS regions amplified with two different universal primer pairs. We also performed morphological characterization of the filamentous fungi and yeast species through observations under the microscope. We investigated the major fungal species of commercial and home-made Nuruks by counting the colony forming units (CFU) and analyzing the occurrence tendency of fungal species. While commercial Nuruks contained mostly high CFU of yeasts, home-made Nuruks showed relatively high occurrence of filamentous fungi. One of the representative Nuruk manufacturers used both domestic wheat bran and imported ones, mainly from US, as raw material. Depending on the source of ingredient, the fungal diversity was somewhat different. Another commercial Nuruk sample was collected twice, once in 2013 and again in 2014, and showed different diversity of fungal species in each year. Nuruks obtained from the southern regions of Korea and Jeju island showed high frequency of yeast such as Saccharomycopsis fibuligera and Pichia species as well as unique filamentous fungus, Monascus species. S. fibuligera was easily found in many Nuruk samples with high CFU. The major filamentous fungi were Aspergillus, Lichtheimia, Mucor and Penicillium species. In order to further our understanding of the isolates and their potential industrial applications, we assayed three enzymes, alpha amylase, glucoamylase and acid protease from 140 isolates out of about five hundred isolates and selected about 10 excellent strains with high enzyme activities. With these fungal isolates, we will perform omics analyses including genomics, transcriptomics, metabolic pathway analyses, and metabolomics followed by whole genome sequencing of unique isolates associated with the basic research of Nuruk and that also has applications in the Makgeolli making process.

• 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.

• Microbiology and Biotechnology Letters
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• v.39 no.1
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• pp.56-62
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• 2011

We investigated quality characteristics of Seoktanju (one of the Korean traditional rice wine) which was fermented using five kinds of Korean commercial Nuruks. The purpose of this study was to research what effects on the quality of Seoktanju by using different Nuruks. We analyzed general component such as each mash's temperature change patterns, pH, titrable acidities, reducing sugar contents, volatile acids, and sugar contents during fermentation periods and studied sensory evaluation of produced Seoktanju (10 days). On the whole, temperature change patterns in the each mashes were depend on room temperature. All Seoktanju's pH was reduced rapidly up to three days after first mashing (pH 3.13-3.57) and after that was increased gradually. The end of fermentation pH was pH 3.6-4.05. Mostly, acidities were indicated high(0.59%) and Nuruk-B was showed highest acid value. These results seems to be different as occasion organic acids producing activity depend on the number of yeast, material contents, optimal temperature in the each mashes by fungi and lactic acid bacteria in Nuruks. In reducing sugar contents and sugar contents, Nuruk-C treatment were showed the highest value with 5.36%, $23^{\circ}brix$, respectively and alcohol content was lowest with 8.6%. In the five kinds of reproduced Seoktanju, alcohol content was the highest in the treated Nuruk-A group. Volatile acid value was the highest with 132.6~263.7 ppm at the 3 day after first mashing day but as the fermentation time goes on, it was reduced sharply by 5.25~5.94 ppm. Sensory evaluation was performed with 5 point scale, the Seoktanju using Nuruk-D was presented by 4 point, while Nuruk-A was presented lowest by 2.77 point on overall acceptability.

• The Korean Journal of Mycology
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• v.43 no.3
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• pp.149-157
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• 2015

We examined taxonomic characteristics and safety of eight Nuruk molds that are widely used for making soybean paste, soy sauce and alcoholic beverages in Korea. HK1 from Hakyeong Fermentation Co., SW101 from Suwon Fermentation Co., CF1001, CF1002, CF1003 from Chungmoo Fermaentation Co. and KACC 93210 are yellow-Nuruk molds, and SW201 from Suwon Fermentation Co. and CF1005 from Chungmoo Fermentation Co. are white-Nuruk molds. Six strains of yellow-Nuruk molds were identified as Aspergillus oryzae. HK1, SW101, CF1001 and CF1003 of yellow-Nuruk molds have middle length of stipes ($711{\sim}1,121{\mu}m$), and CF1003 (for sake) produced less conidia and more hyphae than HK1, SW101 and CF1001 (for soybean paste). CF 1002 used for soy sauce has shorter stipes ($543{\mu}m$) and is clustered into IBLB-group based on omtA gene analysis although the other yellow-Nuruk molds are clustered into ICAo group. KACC 93210 isolated from traditional Korean Meju has very short stipes (average $270{\mu}m$), and showed velvety colonies although the others showed floccose colonies. The strain has different DNA sequences of omtA gene from other strains in NCBI GenBank as well as strains used in Korea, suggesting that it is unique from other strains published. SW201 and CF1005 of white-Nuruk molds were identified as Aspergillus luchuensis or A. luchuensis mut. Kawachii that is known as safe, non-toxigenic fungus. The six strains of yellow-Nuruk molds did not produce mycotoxins including aflatoxin, cyclopiazonic acid, and sterigmatocystin. Therefore, eight strains of Nuruk molds used for making soy sauce, soybean paste and alcoholic beverages in Korea were proved to be safe in this study.

• Applied Biological Chemistry
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• v.13 no.3
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• pp.219-222
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• 1970

Riboflavin in the various materials which used for Takju brewing was determined and its quantitative changes in the Takju mashes which were mashed with polished rice and wheat flour respectively using Nuruk only for enzyme source, and with wheat flour and corn powder respectively using Nuruk and Koji, were checked at 24 hours intervals during the whole brewing period. The results obtained were as follows. a) The riboflavin contents in 100 grams of each materials were: Polished rice $46.9{\gamma}$ Wheat flour $67.3{\gamma}$ Corn powder $73.9{\gamma}$ Nuruk $169.0{\gamma}$ Koji of wheat flour $87.1{\gamma}$ Koji of corn powder $84.4{\gamma}$ b) About 30 to 40 percent of riboflavin in the polished rice, wheat flour and corn powder were losed by steaming at 10 pounds for 50 minutes. c) Riboflavin content in the plots used Nuruk only was decreased during 3 days after mashing and then increased markedly after 5 days and, more or less, decreased after 6 days. Quantitative changes of riboflavin in the plots used Nuruk and Koji showed a rugged curve without decreasing in early stages, and its content was also increased markedly 5 days after mashing and then decreased a little after 6 days. d) Approximately $82{\gamma}$ of riboflavin was determined in 100ml. of the ripened mash of the rice plot and $72{\gamma}$ in the wheat flour plot in the case of using Nuruk only. $88.6{\gamma}$ of riboflavin were determined in 100ml. of the ripened mash of the wheat flour plot and $83.6{\gamma}$ in the corn powder plot in the case of using Nuruk and Koji. e) It was assumed that $28.8{\gamma}$ to $41{\gamma}$ of riboflavin were contained in 100 ml. of finished Takju of the two plots used Nuruk only and 33.6 to 44.5${\gamma}$ in the both two plots used Nuruk and Koji. f) About $47.3{\gamma}$ of riboflavin were determined in 100 grams of Takju cake of the rice plot and $66.2{\gamma}$ in the wheat flour plot used Nuruk only, and $62.9{\gamma}$ in the corn powder plot and $64.5{\gamma}$ in the wheat flour plot used Nuruk and Koji.

• Applied Biological Chemistry
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• v.13 no.1
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• pp.105-109
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• 1970

Thiamin in the various materials which used for Takja braving was determined and its quantitative changes in the Takju mashes which were mashed with polished rice and wheat flour respectively using Nuruk only for the enzyme source, and with wheat flour and corn powder respectively using Nuruk and Koji, were checked at 24 hours intervals during the whole brewing period. The results obtained were as follows. a) The thiamin contents in 100 grams of each materials were: Polished rice 107.8${\gamma}$ Wheat Pour 185.0${\gamma}$ Corn powder 410.2${\gamma}$ Nuruk 347.4${\gamma}$ Koji of wheat flour 170.1${\gamma}$ Koji of corn powder 257.3${\gamma}$ b) About 40 to 50 percent of thiamin in the polished rice, wheat flour and, corn powder were losed by steaming at 10 wounds for 50 minutes. c) The quantitative changes of thiamin in the Takju meshes showed a similar tendency. Thiamin contents were decreased markedly during 2 days after mashing but thereafter, almost unchanged till the mashes were ripened. Its decreasing rates in tile two plots uses Nuruk and Koji wereless thaw those in the two plots used Nuruk only. d) Approximately 6${\gamma}$ of thiamin was determined in 100 ml. of the ripened mash of the rice plot and 7.5${\gamma}$ in tire whet flour plot in the case of using Nuruk only. 12.4${\gamma}$ of thiamin was determined in 100 ml. of the ripened mash of the wheat flour plot and 15.4${\gamma}$in the corn powder plot in the case of using Nuruk and Koji. e) It was assumed that 2.4 to 3.5${\gamma}$ of thiamin were contained in 100 ml. of finished Takju of the two plots used Nuruk only and 5 to 7${\gamma}$ in the two plots used Nuruk and Koji. f) About 43.7${\gamma}$ of thiamin were determined in 100 grams of Takju cake of the rice plot and 56.1${\gamma}$ in the wheat flour plat used Nuruk only, and 81.4${\gamma}$ in the corn powder plot and 57.7${\gamma}$ in the wheat flour plot used Nuruk and Koji.