• 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.

• Food Science and Preservation
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• v.15 no.4
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• pp.512-517
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• 2008

Fermentation characteristics of chestnut-added yakju prepared using various proportions of raw materials such as rice koji, rice flour, cornflour koji and cornflour were investigated. The pH of chestnut-added yakju prepared with cornflour koji and saccharified cornflour showed a higher value than that of chestnut-yakju prepared with rice koji and saccharified rice flour. The total acid content of chestnut-added yakju prepared with rice koji and saccharified rice flour was higher than that of chestnut-added yakju prepared using cornflour koji and sacharified cornflour. The reducing of sugar in chestnut-added yakju prepared with saccharified rice flour or saccharified cornflour was rapid at the first brewing stage, decreased dramatically after 2 days, and then decreased slowly after 5 days of fermentation. The value of L and a, the Hunter values, were high in chestnut-added yakju prepared with cornflour koji, and value b was high in chestnut-added yakju with rice koji. The content of iso-amyl alcohol was the highest of seven kinds of fusel oil found in chestnut-added yakju. Ethanol content increased to $17.6{\sim}18.2%$(v/v) after 8 days of fermentation. The content of lactic acid was the highest of all organic acids in the chestnut-added yakju. Sensory test results on chestnut-added yakju prepared with saccharifed corn flour showed that if rice flour is used as a sugar supplement for chestnut, the yakju prepared using koji had better flavor and taste. If cornflour was used in the preparation of chestnut-added yakju, the used of saccharified cornflour offered superior flavor and taste.

• Journal of Applied Biological Chemistry
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• v.55 no.3
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• pp.163-167
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• 2012

The objective of this study was to determine the effects of Schisandra chinensis on the alcohol fermentation of Korean traditional rice wine 'Yakju', using various methods including alcohol contents, Hunter's color value, organic acid contents, pH value, and sugar contents. The observed results differed according to dosage and fermentation. The S. chinensis Yakju contained various organic acids such as citric, formic, lactic, malic, oxalic acid, shikimic, and succinic acids. In particular, the citric acid contents of S. chinensis Yakju were 9.22, 161.38, 339.28, 458.97, and 634.96 mg/100 mL at doses of 0, 5, 10, 15, and 20% (v/v) of S. chinensis, respectively. The pH of S. chinensis Yakju ranges from 4.11 to 3.57 according to the ratio of S. chinensis. As a result, the citric acid content and pH of S. chinensis Yakju were dependent on the concentration of S. chinensis. On the basis of the Redness value, the S. chinensis Yakju after fermentation (5.16) was approximately 1.8 times more effective than that before fermentation (2.86) at the concentration of 20% (v/v) of S. chinensis. However, S. chinensis has little or no influence on the sugar and alcohol contents of Yakju. These results indicated that S. chinensis was more efficient for improvement of quality characteristics of Yakju.

• The Korean Journal of Food And Nutrition
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• v.17 no.1
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• pp.18-24
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• 2004

Nutritional characteristics and antioxidation effects of Yakju brewed with natural plants(fine tree leaves, bamboo leaves, ginger, cinnamon and licorice root) were tested. With regard to the contents of phenolic compound, Yakju brewed with natural plants was about 1.7 times higher than Yakju which were not brewed with natural plants. In Yakju brewed with natural plants, lactose content was the highest but maltose was not detected. Minerals were detected in the order of P>K>Mg>Ca>Fe and the content of Fe and Na had a little changes during its 30 days storage. Amino acid contents were getting lower during storage. They were about 28% lower compared 3 days with 30 days storage. Electron donating ability of Yakju and its diluents were tested by DPPH. It was found that the electron donating ability of Yakju was lower as the dilution ratio got higher and as the storage terms got longer. Also, Yakju brewed with natural plants has 95.7∼96.7% of electron donating ability during 30 days storage without regard to its dilution ratio. Superoxide dismutase(SOD) like activity was in inverse proportion to dilution ratio and storage days. The highest SOD like activity was shown 51.5% and 53.9% in 3 days storage Yakju brewed with natural plants and in its 2 times diluents, respectively.

• Microbiology and Biotechnology Letters
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• v.39 no.3
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• pp.274-280
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• 2011

Effects of rice varieties, fermentation temperature, nuruks and yeast on the quality of yakju (Korean traditional rice wine) were investigated. Among various yakju made by using some rice varieties, Chucheong yakju produced the highest ethanol of 18.9%. The maximum amount of ethanol was produced when 2% nuruk and 0.8% yeast were added to cooked Chucheong rice and fermented at $20^{\circ}C$ for 10 days. This Chucheong yakju also showed the best overall acceptability. Changes of physicochemical properties and sensory evaluation of the 3 kinds of Chucheong yakju made by cooked rice and uncooked rice and gruel rice were investigated during fermentation. Ethanol contents of uncooked rice- Chucheong yakju and gruel rice- Chucheong yakju were significantly increased from 10.6% and 9.9% after 3 days fermentation to 17.1% and 17.2% after 7 days fermentation. Sensory evaluation revealed the gruel rice - Chucheong yakju was the best in total acceptability with sweety and refreshing tastes.

• Journal of the East Asian Society of Dietary Life
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• v.21 no.2
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• pp.207-214
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• 2011

We investigated the quality characteristics of fermented ginseng Yakju produced using different percentage contents and application dates of ginseng. Although the pH of fermented ginseng Yakju was not significantly different among the various treatment groups, the total acidity was changed depending on the percentage of ginseng content. the application date of ginseng did not influence the total acid content. The amount of volatile acids was higher at a 0.2~0.3% content of white or red ginseng than in other treatment groups. The ginsenoside contents of white and red ginseng used for making ginseng Yakju were 3,555.0 and 4,447.4 ppm, respectively. In ginseng Yakju, total ginsenoside contents were detected at very small amounts of <10 ppm. A total of 15 volatile components were detected in ginseng Yakju. Higher levels of methanol were produced at early application dates. In sensory evaluations, the preference for aroma was higher at white ginseng levels of 0.5% and 1.0% than for other treatment groups, and the taste was judged to be best at a white ginseng content of 0.3%. In the red ginseng treatment group, a red ginseng content of 0.3% was most preferred for both aroma and taste. The taste preference for white ginseng was at 4 days after application, while the taste of the red ginseng treated group was good at the beginning of fermentation.

• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1247-1253
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• 1999

Yakju(rice wine) was sterilized with high-voltage pulses of short time on a batch pulsed electric field(PEF) system. The initial microbial counts of Yakju were 7.52 X $10^4\;CFU/mL$ for total aerobes, 2.20 X $10^4\;CFU/mL$ for lactic acid bacteria and 7.08 X $10^4\;CFU/mL$ for yeasts. The pH, acidity and electric conductivity of Yakju were 3.36, 0.462% and 1.24 mS/cm, respectively. Yakju was treated with 2-250 of pulses exponential-wave formed electric pulses under the field strength of 12.5-25 kV/cm. The critical strengths of the electrical field for the sterilization of Yakju were 7.5 kV/cm for total aerobes, 8.5 kV/cm for lactic acid bacteria and 6.5 kV/cm for yeasts. Logarithmic survival rates decreased linearly at low pulse number, but curvilinearly at high pulse number. The PEF sterilization kinetics of Yakju could be analysed by In s = In A-k In (n) and the sterilization rate constant increased with electric field strength and the size of target microorganisms. No changed in pH, acidity, and the growth of microorganisms were found in the PEF treated Yakju during the storage for 6 weeks at both $4^{\circ}C$ And $30^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.6
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• pp.834-839
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• 2012

The physicochemical and sensory characteristics of Yakju fermented with different ratios of Taraxacum platycarpum (dandelion) root powder (0, 5, 10, and 15%) were investigated. The pH of Yakju decreased and the total acidity and sugar content increased according to the addition of dandelion root powder. Dandelion root powder (15%) showed significantly higher reducing sugar content on the 3rd day of fermentation compared with other groups, including the control. Also, further exposure of fermentation time showed a declining pattern of reducing sugar content. Including control, the alcohol content increased in all Yakju samples fermented with dandelion root powder as fermentation progressed. The Yakju fermented with 5% dandelion root powder showed the highest sensory scores for color, aroma, taste, swallowing, and overall acceptability as $6.38{\pm}1.27$, $5.58{\pm}1.02$, $5.79{\pm}0.98$, $6.08{\pm}1.21$, and $5.96{\pm}0.91$, respectively. In the present study for the production of Yakju, 5% dandelion root powder was the most appropriate amount to be added for the production of Yakju. The result obtained here may provide fundamental data for the traditional Yakju industry, which is interested in using a variety of natural resources.

• The Korean Journal of Food And Nutrition
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• v.6 no.3
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• pp.189-198
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• 1993

This study was carried out to investigate the effect of medium-cooked rice on brewing of yakju which was a traditional rice wine in Korea. The influences of cooking temperature of rice on hydrolysis of rice starch and rice protein were tested, and experimental brewings were done according to the traditional brewing method of Bangmunju in which some medium-cooked rice was used. The results obtained were as follows The hydrolysis of starch and protein in medium-cooked rice at 60~$65^{\circ}C$ was easier than that of full-cooked rice at 80~10$0^{\circ}C$. The amounts of saccharides, total amino acids and extracts In Yakju brewed with the combined use of medium-cooked rice and full-cooked rice were twice as much as those brewed with full-cooked rice only. The results of sensory test of Yakju brewed with the combined use of medium-cooked rice and full-cooked rice were better in taste, color and flavor than those brewed with full-cooked rice only. It was thought that our ancestor's traditional brewing method of Yakju in which medium cooked rice and full-cooked rice were used combinedly was excellent Judging from zymological point of views.

• Journal of the East Asian Society of Dietary Life
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• v.21 no.6
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• pp.882-887
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• 2011

We investigated the physicochemical and antioxidant activity characteristics of Yakju with different ratios (0, 5, 10, and 15%) of dandelion (Taraxacum officinale) root powder in order to find out potential as a functional fermented rice alcohol. Yakju samples were measured to obtain total flavonoid content, total polyphenol content, 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, and reducing power. Total flavonoid and polyphenol contents increased with increasing amounts of dandelion root. The DPPH radical scavenging activity increased with the addition of dandelion root. Also, the reducing power was higher in Yakju with dandelion root compared with controls such as gallic acid, butylated hydroxytoluene, and ${\alpha}$-tocopherol. It is concluded that the Yakju fermented with additional dandelion root is functionally superior to the rice alcohol without dandelion root.