• 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.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.356-362
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• 2000

Yakju(rice wine) was sterilized with high-voltage square-wave pulses of $1\;{\mu}s$ duration at various electric field strengths and frequencies on a serial multiple electrode pulsed electric field(PEF) treatment system consisted of 7 electrodes connected in series. The initial microbial counts of Yakju were $1.88{\times}10^3{\sim}2.13{\times}10^4$ CFU/mL for total aerobes, $1.55{\times}10^3{\sim}2.85{\times}10^4$ CFU/mL for lactic acid bacteria and $1.72{\times}10^3{\sim}2.39{\times}10^4$ CFU/mL for yeasts. The sterilization of microorganisms in Yakju was a first order reaction and the sterilization effect increased as the field strength and the frequency increased. The $D_{Hz}-value$ and the $D_{PEF}-value$ decreased with the electric field strength. Yeast showed lower $D_{PEF}-value$ than bacteria. Lactic acid bacteria showed lower $D_{PEF}-value$ than general aerobic bacteria under the electric field strength below 30 kV/cm, but higher ones under that above 40 kV/cm. The $Z_{PEF}-value$ of general aerobic bacteria, lactic acid bacteria and yeast in Yakju were 39.4, 49.3 and 47.6 kV/cm, respectively. The PEF sterilization resulted in less changes in color and sensory properties than heat sterilization, and the PEF treated Yakju showed superior quality to the heat treated one. The commercial sterilization of Yakju was accomplished with 2-cycle treatment on the tested serial PEF treatment system.

• 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.1
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• pp.46-52
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• 2010

Yakju, a Korean traditional alcoholic beverage, is made from glutinous-rice flour or rice starch with nuruk. In this study, we investigated that fermentation characteristics in yakju was made with glutinous rice and pretreatment. The yeast and nuruk were used Y90-9 and SP1800 (a kind of improved nuruk), respectively. pH and brix degree of yakju, brewed with glutinous rice flour by heating, were higher than the others during fermentation process. Total acid contents were 0.2~0.3 and the highest alcohol degree (15.75%(v/v)) was fermented glutinous rice flour by heating. Reducing sugar contents were 3.5-3.9 mg/mL. Yakju, which brewed with glutinous rice flour, of amino acid degree, UV absorbance and color degree was higher than yakju which brewed with glutinous rice starch. Succinic acid was the highest organic acid among 6 organic acids and free sugar contents described as glucose > maltose > fructose. Twenty one components were identified including 3 alcohols, 17 esters and one aldehyde. Of these, ethyl palmitate, which was described as mild flavor, was the highest %area except ethyl alcohol. Overall, the fermentation performed using glutinous rice flour by heating and improved-nuruk showed the best results for yakju production.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.4
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• pp.801-804
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• 1999

Quality characteristics of yakju prepared by different yeast strains such as Saccharomyces cerevisiae S 2, Saccharomyces cerevisiae S 6 and Saccharomyces cerevisiae IFO 1950 were investigated during fermentation. The pH in all kinds of yakju was gradually decreased until 6 days and then it was constant. In stage of fermentation, acidity of yakju made of Saccharomyces cerevisiae S 6 was higher than others. At the beginning stage of fermentation, ethanol contents were in the range of 0~2% increased to 9.5~11.5% after 10 days. Yakju made of Saccharomyces cerevisiae S-2 showed higher ethanol contents than others. Free sugars in yakju were found to be glucose and maltose. The contents of free sugars were decreased until 6 days and they were not detected. The content of ethanol in yakju showed the highest value at the 6th day and those of yakju A, B and C were 11.9, 9.5, 10.9%, respectively. Main organic acids in yakju were citric acid and lactic acid. The content of citric acid in yakju B was higher than others.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.2
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• pp.277-284
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• 2005

Micro-filtration (MF) or ultra-filtration (UF) system with hollow-fiber cartridge was introduced in order to improve the Quality level of commercial foxtail millet Yakju, which has an off-flavour and/or undesired colour after the thermal treatment. The filtration effects of cartridges such as MF (0.65, 0.45, 0.2, 0.1 $\mu$m) and UF (500 K dalton) were investigated. The physicochemical and sensory characteristics of the Yakju were then evaluated during the 6 months storage at room temperature. The exclusion ability of microorganism in samples was confirmed in all cartridges, but 0.45 pm MF-cartridge was suitable in the Yakju manufacture due to its superior filtration rate and efficiency. Changes in reducing sugar and colour difference of foxtail millet Yakju untreated or treated by heat ($65^{\circ}C$${\times}$10 min) were observed during the storage; after 6 months the L-value of thermal-treatment sample was decreased and its b-value, however, significantly increased so that its color became dark, in comparison to non-thermal treatment sample. This decrease of reducing sugar is assumed that color change is associated with non-enzymatic browning reaction. Sensory Quality of foxtail millet Yakju produced by non-thermal treatment was better than that of thermal treatment.

• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.818-822
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• 2004

Gastroprotective effects of Korean rice-wine (Yakju) in two types of acute experimental gastric ulcer induced in rats and in mice were evaluated. Korean rice-wine were administered to 24-hr fasted rats 30 min before administration of 60% EtOH in 150 mM HCl or absolute ethanol. Korean rice-wine prevented formation of gastric ulcers induced by 60% EtOH in 150 mM HCl at oral doses of 250-1,000mg/kg and reduced gastric ulcers induced by absolute ethanol at oral doses of 62.5-1,000mg/kg, and inhibitory effect against 30% alcohol treatment for 7 days (twice/day). These results suggest Korean rice-wine have inhibitory effects on gastric lesion and ulceration.

• Journal of the East Asian Society of Dietary Life
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• v.22 no.5
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• pp.642-648
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• 2012

In the present study, yakju was developed added with 100~400 g of meoru (Vitis coignetiae). We analyzed the volatile flavor compounds and investigated the sensory properties of meoru yakju. The volatile flavor compounds were isolated from in fusions by Porapak Q column adsorption. The concentrated flavor extract was analyzed and identified by GC (gas chromatography) and GC-MS (gas chromatography-mass spectrometry) analyses. Thirty-five compounds, including five alcohols, nine esters, seven acids, four hydrocarbons, three ketones, and seven other compounds, were identified. The total number and content of volatile flavor compounds in control yakju were the highest, but they decreased as the amount of added meoru increased. On the other hand, yakju containing 200 g of meoru was characterized by the highest content of ester compounds, and it was the most preferred in terms of flavor, color, taste, and over all acceptability. Based on these results, addition of 200 g of meoru to 1,715 g of control yakju was determined to be the optimal condition for making meoru yakju.

• Korean Journal of Food Science and Technology
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• v.13 no.4
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• pp.307-313
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• 1981

The components of several kinds of Sokokju (old Korean cleared rice wine) prerared in the laboratory by two steps mashing and commercial Yakju (Korean cleared rice wine) were evaluated. The Sokokju mashed with half steamed waxy rice in tile primary fermentation yielded higher contents of alcobol and extract. Especially considerable amount of pyruvate was contained in it. The commercial Yakju sample contained abundantly tartarate and citrate while dominant organic acids in the fermented mashes of Sokokju were lactate, fumarate and succinate. The taste characteristics of the Sokokju brewed with half steamed waxy rice were most acceptable to the sensory panel.

• Korean Journal of Food Science and Technology
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• v.30 no.6
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• pp.1420-1425
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• 1998

Rice wines, Yakju-type, were brewed with typical raw materials plus powdered acorns, and storage qualities of the fermented wines were examined. Initial optical densities of the acorn added-rice wines were shown around 0.116 at 660 nm and then decreased to $0.06{\sim}0.075$ after 10 days storage at $4^{\circ}C$. Organic acid contents in the acorn added-rice wines were lower than that of the control: the contents were lactic, succinic, citric, malic, oxalic and fumaric acid in order; and gallic acid, a kind of tannic substances was 0.39 mg%. Peroxide values of the acorn added-rice wines were not markedly changed for 9 days, remaining as low as $2{\sim}3\;meq\;kg^{-1}$ lard of lard, but that of the control was increased to $265\;meq\;kg^{-1}$ lard. As the results of clarity, acidity and antioxidation, the acorn added-rice wines appeared to be preservable, owing to tannic substances extracted from acorn powder.