• Food Science and Preservation
• /
• v.19 no.2
• /
• pp.308-314
• /
• 2012

Two hundred and twenty three yeast strains were randomly isolated from Korean traditional $nuruk$. Among them, six urease producing yeast strains (designated JJA, JJB, JJ22, SHA, SHC and SH10) were selected on the Christensen urea agar plates. They showed the same pattern in the PCR-RFLP analysis of the ITS I-5.8S-ITS II region digested with $Hae$III and $HinF$1 restriction endonucleases. Its DNA sequences showed 100% (strains SHA, SHC and SH10) and 99.8% (strains JJA, JJB and JJ22) identity with those of $Issatchenkia$ $orientalis$ type strain ATCC 24210. Phylogenetic analysis resulted in that all the strains were closely related to $I.$ $orientalis$. Two representative strains, JJ22 and SH10, showing the highest urease activities were selected for further characterization. Their morphological, physiological and biochemical characteristics were also the same as $I.$ $orientalis$. Therefore, both the two strains were identified as $I.$ $orientalis$. They could grow at a wide range of temperature between $20-40^{\circ}C$ as well as pH between 2.0 and 10.0. However, a higher level urease activity were obtained at acidic pH than that at alkalic pH. The maximal level of urease activity was obtained at $30^{\circ}C$ (strain SH10) or $35^{\circ}C$ (strain JJ22) and in a liquid medium adjusted to the initial pH 5.0.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.28 no.5
• /
• pp.1017-1021
• /
• 1999

Shindari, a traditional low alcoholic drink in Cheju island, was prepared with nuruk and the rice porridge. The rice porridge was fermented with 10% nuruk at a temperature of $25^{\circ}C,\;35^{\circ}C,\;45^{\circ}C$ for 24 hours. In all temperature, total acidity and oBrix were increased gradually and pH were decreased gradually and viscosity were considerably decreased after 2 hours and then slightly decreased. Alcohol contents were also increased during fermentation and especially at $45^{\circ}C$. The organic acids were mainly found phytic acid and succinic acid. The fermented liquids rice porridge contained maltose and glucose as free sugar, amount of them increased during fermentation. Lactic acid bacteria cell count increased at higher tem perature of fermentation and reached to $10^{7}\;cfu/ml\;at\;35^{\circ}C$ for 10hr. In conclusion, the optimal fermentation conditions Shindari preparation were at $35^{\circ}C$, 24hrs. pH, titratable acidity, viscosity and soluble solids in the optimal fermentation condition were 4.2, 0.18%, 190cp, $12.2^{\circ}Brix$, respectively.

• Korean journal of food and cookery science
• /
• v.31 no.1
• /
• pp.9-17
• /
• 2015

Shindari is a traditional fermented drink of Jeju in Korea, which is made with boiled barley and nuruk for short fermentation periods. This study determined chemical, microbiological, and sensory characteristics of the modified Shindari with 15% carrots as an additive (carrot Shindari), and this study compared it with a traditional Shindari as a control. After fermentation at $30^{\circ}C$ for a day, the pHs of the carrot Shindari and traditional Shindari largely decreased, and the total acidities increased in both of the Shindari. The significantly higher scores of Hunter's color values were observed more in carrot Shindari than in traditional Shindari. Also, carrot Shindari (0.4954 g/100 g) had a significantly higher content of vitamin C than traditional Shindari (0.0030 g/100 g). The most abundant free sugar and organic acid were glucose and lactic acid, respectively, in both of the Shindari. The total numbers of bacteria, fungi and lactic-acid bacteria in both samples increased by log 3 CFU/mL after fermentation. Based on 16S ribosomal RNA gene analysis, the dominant lactic-acid bacteria was Pediococcus acidilactici in both samples. The DPPH (1.1-diphenyl-2-picrylhydrazyl) radical scavenging activity of carrot Shindari (60.13%) was higher than that of traditional Shindari (23.70%). In sensory evaluations (taste, flavor, color, and overall acceptance), the carrot Shindari had higher scores in all these values. In this study, the modified Shindari with carrot presenting high sensory characteristic as well as chemical and microbiologic characteristics provide an opportunity to improve the application of a traditional fermented drink of Jeju, Shindari.

• Food Science and Preservation
• /
• v.21 no.6
• /
• pp.892-902
• /
• 2014

The quality characteristics of Takju were investigated according to the different rice varieties and mixing ratio of Nuruk for the advanced quality of Takju. The yeast was selected by alcohol-producing ability. Then a liquid starter was prepared using brewing fungi (Aspergillus luchuensis 34-1 and Lichtheimia ramosa CN042), and rice Nuruk was manufactured with two rice types (Chucheong and Hanareum). The quality characteristics of Takju were investigated based on the rice type and the mixing ratio of A. luchuensis 34-1 and Lich. ramosa CN042 (1:0, 0:1, 1:1, 1:3). S. cerevisiae Y268 showed an alcohol yield of $9.3{\pm}0.33%$ at a 0.3% concentration in the YPD broth medium, and the rice Nuruk with A. luchuensis 34-1, regardless of rice type, was confirmed to have a higher enzyme activity and physiochemical property than Lich. ramosa CN042. According to the quality analysis of Takju, the physiochemical property was increased for the fermentation period, and the acidity differed by type of fungi and rice. The quality of Takju was changed with the composition differences of organic acid and free amino acid by rice type and mixing ratio. As a result of the sensory evaluation of Takju, the preference for it was increased with the Hanareum and A. luchuensis 34-1, respectively. Thus, this study shows the possibilities for activating the industry of traditional liquor by improving the Nuruk and Takju manufacturing technique.

• The Korean Journal of Mycology
• /
• v.38 no.2
• /
• pp.184-188
• /
• 2010

The goal of this study was to screen a useful yeast for Korean traditional pear Yakju (KTPY) brewing and develop its brewing process. Cooked non-glutinous rice and nuruk were mixed, and added into pear juice with various Saccharomyces cerevisiae and then fermented at $25^{\circ}C$ for 7 days. Among several alcohol fermentation yeasts, ethanol contents was the highest in pear Yakju made by S. cerevisiae K-7 and also showed high ethanol content in pear Yakju which was made by commercial S. cerevisiae C-2. Therefore, we selected S. cerevisiae K-7 and S. cerevisiae C-2 as suitable yeasts for brewing of KTPY. Maximal ethanol production (10.4%) was obtained when cooked non-glutinous rice (100 g) and nuruk (30 sp/g) were mixed and added into pear juice (600 ml) with S. cerevisiae K-7 (5%) and fermented at $25^{\circ}C$ for 7 days and also its antihypertensive angiotensin I-converting enzyme (ACE) inhibitory activity was 57.2%. Addition of antihypertensive starchy materials into the mash was not affected in ACE inhibitory activity and total acceptability of KTPY.

• Korean Journal of Food Science and Technology
• /
• v.34 no.4
• /
• pp.673-677
• /
• 2002

To develop a new traditional liquors using purple-fleshed sweet potato, the condition of alcohol fermentation was investigated by adding different concentrations $(5{\sim}75%)$ of cooked purple-fleshed sweet potato into mash and 10% nuruk, and fermenting for $5{\sim}15$ days. The maximum amount of ethanol (15.4%) was produced when 20% cooked purple-fleshed sweet potato and 10% nuruk were added into mash and fermented by S. cerevisiae at $25^{\circ}C$ for 15 days. The acceptability and physiological functionalities of the purple-fleshed sweet potato liquors were also investigated and compared. PSP-10 purple-fleshed sweet potato liquor prepared by adding 10% cooked purple-fleshed sweet potato into mash showed the best acceptability in the sensory evaluation test and color test $(pink{\sim}red)$; its fibrinolytic, electron-donating, and tyrosinase inhibitory activities were better than those of other purple-fleshed sweet potato liquors and wine.

• Food Science and Preservation
• /
• v.16 no.1
• /
• pp.33-39
• /
• 2009

To evaluate the quality of brown rice vinegar made by traditional fermentation in terms of Zymotechnic data and material content, vinegars prepared using a traditional leavening agent and yeast were compared. Amino acid, total nitrogen, free sugar, organic acid, and mineral levels were assessed, with vinegars made with initial brown rice contents of 12.36% (w/v). Vinegar made using Nuruk as fermenting agent (traditional fermentation, TF), with a brown rice content of 20% (w/v), and vinegar prepared using yeast for fermentation (control fermentation, CF), with a brown rice content of 12% (w/v) were compared. TF vinegar had a total nitrogen content about 2.0.4.6-fold that of CF vinegar. Total nitrogen in TF vinegar was 350.460 mg/100g, and in CF vinegar the level was 100.140 mg/100g. TF vinegar had more minerals, free sugars, and amino acids compared with CF vinegar. When free sugar was assessed, TF vinegar had a glucose level of 3.45 g/100g, double that of CF vinegar. Amino acid levels were five-fold higher in TF vinegar then in CF vinegar. When brown rice content was 36% (w/v), the amino acid level was $6088.22\;{\mu}g/mL$ in TF vinegar and $1194.05\;{\mu}g/mL$ in CF vinegar.

• Journal of the Korean Society of Food Culture
• /
• v.11 no.5
• /
• pp.601-608
• /
• 1996

Fermentation characteristics of Baikhaju (a typical Korean traditional alcoholic beverage) were investigated during fermentation with differently treated rice samples, which were steamed rice (SR), plain steamed rice bread (RB), rice porridge (RP) and roasted rice (RR). The RB sample showed an excellent fermentation efficiency with the highest alcohol production (20.84%). The SR and RR samples showed 17.79% and 17.31% of alcohol production, respectively. The RP sample was the lowest alcohol production (11.47%). The pH values of all the beverage samples were similar and were ranged from 3.6 to 3.9. The fermentation periods of RB and RR samples were longer than the SR and RP. The inner temperature and microbial growth in all the beverages increased at each of input steps of the rice and Nuruk (a Korean-style bran koji). Fusel oil content of the SR and RP samples (613.6 ppm) was higher than that of RR (482.7 ppm). The RB sample with the best fermentation efficiency had the lowest fusel oil content (341.8 ppm). The RP sample showed the highest score in sensory evaluation and RB sample showed the lowest. The results on sensory evaluation were contrary to those on the fermentation efficiency.

• Journal of Microbiology and Biotechnology
• /
• v.25 no.2
• /
• pp.217-226
• /
• 2015

Metabolite profiles of seven commercial vinegars and two traditional vinegars were performed by gas chromatography time-of-flight mass spectrometry with multivariate statistical analysis. During alcohol fermentation, yeast, nuruk, and koji were used as sugars for nutrients and as fermentation substrates. Commercial and traditional vinegars were significantly separated in the principal component analysis and orthogonal partial least square discriminant analysis. Six sugars and sugar alcohols, three organic acids, and two other components were selected as different metabolites. Target analysis by ultra-performance liquid chromatography quadruple-time-of-flight mass spectrometry and liquid chromatography-ion trap-mass spectrometry/mass spectrometry were used to detect several metabolites having antioxidant activity, such as cyanidin-3-xylosylrutinoside, cyanidin-3-rutinoside, and quercetin, which were mainly detected in Rural Korean Black raspberry vinegar (RKB). These metabolites contributed to the highest antioxidant activity measured in RKB among the nine vinegars. This study revealed that MS-based metabolite profiling was useful in helping to understand the metabolite differences between commercial and traditional vinegars and to evaluate the association between active compounds of vinegar and antioxidant activity.

• Microbiology and Biotechnology Letters
• /
• v.47 no.4
• /
• pp.530-535
• /
• 2019

Diverse types of nuruks (traditional Korean fermentation initiators) were examined in order to isolate thermotolerant yeast strains capable of utilizing xylose as a carbon source. Among twenty yeast strains that grew at 46℃, MBY/L1597 showed a notably higher specific growth rate than other strains. This strain was identified as Millerozyma farinosa. While the control strain M. farinosa KCTC27412 (= CBS7064) did not show xylose reductase (XR) activity and apparent growth at 46℃, M. farinosa MBY/L1597 exhibited XR activity of 4.98 ± 0.49 U/mg protein when NADPH was used as a cofactor. M. farinosa MBY/L1597 cultured at 46℃ produced (9.87 ± 1.00 g/l) xylitol from 20 g/l xylose, corresponding to approximately 50% yield. M. farinosa MBY/L1597 was deposited at the Korean Collection for Type Cultures as KCTC27797.