• Journal of the East Asian Society of Dietary Life
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• v.25 no.6
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• pp.1041-1048
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• 2015

This study was performed to produce quality vinegar using different types of nuruk, which is the most effective in making traditional brown rice vinegar. The vinegar was produced with 20% vinegar starter, and pears were added to reduce the nuruk aroma. Three different types of Nuruk that were prepared were rice, wheat, and a rice+wheat (1:1) combination. The total acidities of brown rice pear vinegar made from rice-nuruk, wheat-nunuk, and rice+wheat-nuruk were 8.1%, 7.5%, and 6.4%, respectively. Free sugars, including glucose, galactose, and fructose, were highly detected from all three vinegar samples. Acetic acid and lactic acid were the major organic acids in all three vinegar samples. For free amino acids, alanine, glutamic acid, and arginine were mainly detected in all three vinegar samples. Total phenolic compounds were higher in brown rice pear vinegar made of rice-nuruk than in that made of wheat-nuruk, whereas total flavonoids showed the opposite pattern. DPPH-radical scavenging activity was higher in brown rice pear vinegar made of wheat-nuruk than in that made of rice-nuruk.

• Journal of the East Asian Society of Dietary Life
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• v.27 no.2
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• pp.159-167
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• 2017

In this study, quality characteristics of yakju fermented with byeo-nuruk prepared using rice, wheat, and water were investigated. Five different mixture ratios were considered for byeo-nuruk preparation. A comparative analysis of commercial yakju and byeo-nuruk yakju was also performed. The results showed no significant differences in pH, total acidity, and total soluble solids of byeo-nuruk yakju immediately following fermentation. The byeo-nuruk yakju alcohol content increased with increasing wheat proportion. Lactic and succinic acid were the major organic acids of byeo-nuruk yakju, and the major volatile components were isoamyl alcohol and linalool. Yakju prepared using material D had the highest volatile component content and high preference evaluation scores for taste and overall acceptability. Compared to commercial yakju, byeo-nuruk yakju had less total acidity, soluble solids, and volatile acids, whereas its pH level and amino acid content were higher. No significant differences were observed between commercial yakju and byeo-nuruk yakju in terms of sensory evaluation.

• Journal of the East Asian Society of Dietary Life
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• v.18 no.1
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• pp.41-48
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• 2008

This study focused on the alcohol fermentability of traditional Nuruk, as well as yeast containing traditional Nuruk, in the production of Yakju. The fermentation performed with 30% Nuruk was effective with regard to alcohol yield. In addition, the fermentation containing 70% Nuruk showed the highest titratable acidity due to increased amounts of organic acids (succinic acid, oxalic acid, malic acid, acetic acid), which, however, negatively influenced the Yakju quality. Moreover, microbiological contamination always occurred in the fermentations using only Nuruk. In contrast, in the experiments with the yeast containing Nuruk, higher alcohol content and lower titrable acidity were obtained, independent of the Nuruk ratio used, positively effected the Yakju taste and flavor. Overall, the fermentation performed using the yeast containing 30% traditional Nuruk showed the best results for Yakju production.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.535-542
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• 2019

The purpose of this study was to obtain basic data necessary for making a nuruk salt by comparing and analyzing the ingredients of various nuruk salts, and to select a nuruk salt that meets the users' needs. We selected the types of nuruk as the ihwaguk, miinguk, baekguk, and koji to identify the characteristics of the nuruk, and then analyzed the chemical characteristics after manufacturing the nuruk salts under the same conditions of fermentation, such as material ratio and temperature. In the manufacture of nuruk salt, the pH level dropped from 6.2~6.5 before fermentation to 6.1~6.2 three days after fermentation. The Acidity increased from 0.16~0.18 before fermentation to 0.22~0.25 after fermentation and there was no difference between the nuruk. The sugar content has risen since fermentation, and nuruk salt made by koji showed the largest increase in the sugar content. The salinity of the nuruk salt was raised to 37~44 after fermentation from 30~32 before fermentation and indicated largest increase in nuruk salt made by koji. Organic acids of nuruk salt were detected in the order of acetic acid, oxalic acid, malic acid, lactic acid, and citric acid. The oxalic acid of the baekguk salt was found to be 0.77 mg/mL, 2.3 times more of the koji, and the succinic acid was also found to be the highest with 1.19 mg/mL. Malic acid, lactic acid, acetic acid, and citric acid were found to have the highest amount of koji salt at 0.29 mg/mL, 1.48 mg/mL, and 0.12mg/mL, respectively, making it a better taste to be soft than other nuruk salt.

• 한국균학회소식:학술대회논문집
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• 2015.11a
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• pp.39-39
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• 2015

Korean traditional Nuruk has been developed with various materials and shapes according to geographical environments and climates of their origins. Nuruk is also known as kokja in Korea, reflecting the understanding that microorganisms such as wild fungi, yeasts, and lactobacillus bacteria are naturally inoculated and reproduced. The objective of this study is to identify the characteristics of traditional Nuruk through recreating traditional production methods detailed in ancient Korean documents. In the present study, a total of 58 different kinds of Korean traditional Nuruk were prepared, including 46 kinds of recreated products. Each Nuruk sample was evaluated for its enzymatic activities, including glucoamylase, protease, and glucanase. Their suitability for alcoholic beverage production were compared to each other. To isolate valuable microorganisms from Nuruk samples, alcoholic beverages produced using each sample were subjected to sensory evaluation to determine their taste. In addition, metabolite changes in traditional alcoholic beverages fermented with different kinds of Nuruk were analyzed through mass-based metabolomics approach. This study presents, for the first time, the traditional production methods written in ancient Korean documents using workable production methods supported by modern technologies. In addition, this study analyzed the characteristics of reproduced Nuruk. It could be utilized as a basis for studying traditional Korean traditional alcoholic beverages and their valuable microorganisms.

• Journal of Biomedical and Translational Research
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• v.19 no.4
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• pp.103-109
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• 2018

Aspergillus luchuensis 34-1 was inoculated into wheat pellets with different conditions of raw materials to produce nuruk. The degree of substrate reactivity improvement of steam treated raw materials compared with that of non-heat treated was analyzed. The water content of the pellet was adjusted to 25% and 35%, and steam treatment for 10 minutes improved the substrate reactivity at 2.1-fold and 3.1-fold, and sterilization was also possible. The characteristics of improvement pellet nuruk were investigated according to the degree of crushing and water content of raw materials according to the temperatures and humidities ($23^{\circ}C$, $30^{\circ}C$ and RH 60%, RH 80%). The pH of the pellet nuruk was higher depending on the temperature, humidity and moisture content of the koji were lower, and the pH of the flour-pellet nuruk was lower than that of 2 mm milling wheat-pellet nuruk according to milling degree. It can be seen that the milling degree affects the growth of mold. The acidity and amino acid were generally higher as fermentation time increased. Also, the higher the incubation temperature, humidity and moisture content, the higher the value. Glucoamylase activity was significantly the highest in moisture content 35% D2b nuruk, cultured at $30^{\circ}C$ and 80% RH for 38 hours. This is higher than the previous reports on glucoamylase of rice-koji or commercial nuruk using fungi isolated from traditional nuruk. From these study, it is expected that making of improvement pellet nuruk would save the fermentation time considerably compared with traditional nuruks.

• Microbiology and Biotechnology Letters
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• v.28 no.5
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• pp.303-308
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• 2000

The character-istics of the volatile flavor components of traditional Korean Nuruk produced by Aspergillus oryze NR 3-6 and Penicillium expansum NR 7-7 were investigated. Volatile flavor of Nuruk was identified twenty-one components by gas chromatography-mass spectronmeter. Major flavor components were alkanes such as tridecan, tetradecan, penta-decane, hexadecane, heptadecane, octadecan, undecane, and dodecane.

• Journal of the East Asian Society of Dietary Life
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• v.21 no.6
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• pp.877-881
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• 2011

This study was investigated the quality characteristics of Makgeolli containing different types of Nuruk grain inoculated with A. oryzae N041. In an analysis of the quality characteristics of four types of Nuruk grain, mung beans Nuruk grain had higher acidity, amino acidity and saccharogenic power than rice Nuruk grain. In an analysis of four types of brewed Nuruk grain, mung beans Nuruk grain had the highest sugar and reducing sugar contents. On the other hand, mung beans Nuruk grain had the lowest alcohol content. Citric acid, malic acid and succinic acid have been identified as the major organic acids in Makgeolli. The amounts of organic acids were 1,748.5 mg% in rice Nuruk grain, 1,553.9 mg% in mung beans Nuruk grain, 1,003.2 mg% in barley Nuruk grain and 940.8 mg% in adlay Nuruk grain. In particular, Makgeolli brewed with mung beans Nuruk grain had the highest content of the organic acids, which is expected to deepen its flavor.

• 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%).

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.6
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• pp.928-934
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• 2015

The objective of this study was to reduce Nuruk flavor in Korean rice-distilled liquor using different ratios of $Sumizyme^{TM}$ and Nuruk. After 9 days of fermentation at $28^{\circ}C$, alcohol contents and pH were 16.0~17.1% and 3.82~4.16, respectively. An increased ratio of $Sumizyme^{TM}$ decreased alcohol content while increased pH of the mash. In alcohol contents, there were no significant differences up to 30% substitution of Nuruk to $Sumizyme^{TM}$. A descriptive analysis was conducted with trained panelists for determining the intensity of Nuruk flavor. The intensities of Nuruk flavor in mashes and distilled liquors brewed by traditional Nuruk, cultured Nuruk, and a mixture of 30% $Sumizyme^{TM}$ and 70% cultured Nuruk were evaluated. The mash and distilled liquor prepared using a mixture of 30% $Sumizyme^{TM}$ and 70% cultured Nuruk showed significantly lower intensities of Nuruk flavor when compared with those of mashes and distilled liquors produced by the traditional and cultured Nuruk.