• 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 Science and Nutrition
• /
• v.38 no.1
• /
• pp.76-82
• /
• 2009

Wheat is the most widely cultivated cereal and an important source of dietary protein worldwide. Wheat allergy, defined as an adverse immunologic reaction to wheat, encompasses a broad spectrum of disorders with different pathomechanisms and clinical manifestation. The Nuruk, a traditional Korean Koji for brewing, was made with wheat flour and fermenting microbes such as bacteria, yeast and mold. The strains grown on Nuruk secrete various enzymes as amylase and protease. By the activation of such enzymes, starch and proteins in Nuruk are hydrolyzed to sugar and amino acid. Therefore, it is supposed to reduce allergic proteins in wheat. To study quality properties and degradation degree of allergenicity in Nuruk by fermentation, we investigated the changes of general ingredients and allergenicity in Nuruk during fermentation. Moisture contents was decreased from 24.2% to 13.6% during fermentation. Crude lipid and protein contents were gradually increased during fermentation. After 15 days of fermentation, reducing sugar and total sugar contents were reached its maximum level, and they were 27.45% and 39.00%, respectively. Acid and neutral protease activity were significantly increased during fermentation, but alkaline protease activity was not detected. ${\alpha}$-amylase activity was gradually increased and showed maximum level about 2,833.00 U/g after 15 days of fermentation. Glucoamylase activity was the highest level about 497.9 U/g after 10 days of fermentation. The increase of these proteolytic and saccharogenic enzyme activities will provide efficient condition for production of rice wine. Also, protein fractions were isolated from Nuruk, and degradation of these proteins during fermentation were confirmed by SDS-PAGE. IgE immunoblotting using patient's sera with wheat allergy was performed to confirm allergenic protein in Nuruk. These results as fermentation of Nuruk will provide a useful tool for developing safer wheat products to prevent wheat allergy.

• Microbiology and Biotechnology Letters
• /
• v.38 no.4
• /
• pp.373-378
• /
• 2010

Studies on standardization and quality upgrade of nuruk which is a basic component in brewing are required to increase the quality level of Korean traditional rice wines and to develop the technology for practical use of it. It is important to isolate best strains, to improve the properties and effectively preserve them for brewing industry. In this study, 16 commercial nuruk samples were obtained from the commercial markets located in Chungcheong areas in Korea. 174 fungal strains were isolated from the samples on DG18 medium using a dilution plating method and then screened for enzyme activity and acid production. The active strains were identified based on the morphological characteristics and ITS sequence analysis. Out of 174 strains, 12 strains showed high amylase activity. Especially, Rhizopus sp. CN084, CN174, Aspergillus sp. CN161 and Mycocladus sp. CN042 showed high saccharogenic power and dextrinogenic enzyme activity on cooked wheat bran medium. On the other hand, Aspergillus sp. CN010, CN161, Rhizopus sp. CN105, CN168 and Rhizomucor sp. CN088 produced high acid production on the same medium. Our results showed that the active strains may be used as microbial sources for nuruk starter with good quality in brewing.

• Korean Journal of Food Science and Technology
• /
• v.44 no.2
• /
• pp.207-215
• /
• 2012

Six different mashing types ((A) $koji$+purified enzyme, (B) $koji$+crude enzyme, (C) $koji$+$nuruk$, (D) $koji$+purified enzyme+$nuruk$, (E) $koji$+crude enzyme+$nuruk$, (F) purified enzyme+$nuruk$) had been established, according to fermentation agents and a mixing rate of rice $makgeolli$, in this study. The alcohol content was the highest in the mashing type (C), which was 13.6%, followed by (D) 13.5%, (A) 13.1%, (B) 12.9%, (E) 12.7% and (F) 12.1%. The reducing sugar content of (A) was the highest with 401.6 mg% and those of (B), (C), (D) and (F) were between 337.3- 380.9 mg%. The alcohol components were found and tended to increase during the fermentation. The oligo-saccharides content was the highest in (D) with 1251.3 mg%, which was followed by (E) 1,219.2 mg%, (C) 1,141.4 mg%, (A) 1,049.9 mg% and 973.8 mg% in (B). The total free amino acid was highest in (B) with 781.4 mg% and followed by (C) 703.2 mg%, (D) 702.6 mg%, (E) 678.7 mg%, (A) 630.4 mg% and (F) 328.7 mg% in order. There were 16 different types of volatile flavor components, in the mashing types (A) and (B), in addition to 15 different types of those in type (C), as well as 14 different types of those in (D), (E) and (F). There were significant differences in the overall preference between the type (A) and (C).

• The Korean Journal of Mycology
• /
• v.26 no.4 s.87
• /
• pp.478-486
• /
• 1998

The isolates of Rhizopus collected from Korean traditional fermented food meju and nuruk, were compared with the well known species of Rhizopus donated. The isolates of Rhizopus were identified with the numerical analyses calculated from RAPD-DNA bands, and confirmed with the microscopic observations of morphological features on PDA. The isolates of R. oryzae purchased were segregated through the results of RAPD or the morphological features. The species of R. nigricans, known as an illegitimate species, were different from those of R. stolonife and it is estimated that they are species of Rhizopus, again. According to microscopic observations and the result of RAPD, Some isolates of R. oryzae purchased belong to R. nigricans and are completely different from R. oryzae in their growth. The isolates of R. nigricans included with several isolates of R. oryzae identified for the different phenotypes and were heterogenous. The isolate of R. oligosporus were speculated to be different from morphological features of Rhizopus, but to be similar to the species of Absidia on the apophysis of sporangium. Its sporangiophore or mycelium was observed to be dark black, but the sporangia were not in those of R. oligosporus. The isolates collected from Korean traditional nuruk showed genetic diversity, and also considered to be different tastes in Korean rice wines.

• Food Science and Preservation
• /
• v.5 no.4
• /
• pp.374-379
• /
• 1998

A vinegar was prepared from uncleaned rice by two step fermentation, alcohol fermentation followed by acetic acid fermentation. The contents of alcohol reached to 10.8% during the alcohol fermentation of uncleaned rice with nuruk, and acidity reached to 5.78% during the acetic acid fermentation. Acidity and pH of vinegar of two step fermentation were higher than those of commercial vinegars. 'L' value(Light) of the vinegar was lower, 'a' and 'b' value were higher than those of commercial vinegars. The contents of acetic acid, malic acid, citirc acid and tartaric acid were hish in organic acid of vinegars. The content of each ofganic acid in vinegars was remarkably different. The content of free amino acids was 2199.7${\mu}\ell$/ml in the vinegar produced by two step fermentation which is higher than that of others.

• 한국생물공학회:학술대회논문집
• /
• 2001.11a
• /
• pp.311-314
• /
• 2001

In order to develop a new Korean traditional liquor using acasia, the condition of alcohol fermentation was investigated by addition of 5%, 10%, 15% nuruk and 10% acasia into mash, The maximum amounts of ethanol was produced when 10% acasia flower and 15% nuruk was added in cooked rice and fermented by S, cerevisiae at $25^{\circ}C$ for 20 days, The acceptability and physiological functionalities of acasia liquors with different concentrations(5%, 10%, 15%, 30%. 50%) of acasia flower were compared. The A -15 liquor which was brewed by addition of 15% acasia flower into mash showed the best acceptability, and its electron-donating ability and nitrite-scavenging activity were also high.

• Mycobiology
• /
• v.41 no.3
• /
• pp.139-144
• /
• 2013

Makgeolli is a traditional cloudy-white Korean rice wine with an alcohol content of 6~7%. The present study investigated the morphological characteristics, carbon-utilizing ability, fatty acid composition, alcohol resistance, glucose tolerance, and flocculence of Saccharomyces cerevisiae Y98-5 and Pichia anomala Y197-13, non-S. cerevisiae isolated from Nuruk, which is used in brewing Makgeolli. Similar morphological characteristics were observed for both isolated wild yeast strains; and the carbon source assimilation of Y197-13 differed from that of other P. anomala strains. Strain Y197-13 was negative for D-trehalose, mannitol, arbutin, I-erythritol, and succinic acid. The major cellular fatty acids of strain Y197-13 included C18:2n6c (33.94%), C18:1n9c (26.97%) and C16:0 (20.57%). Strain Y197-13 was Crabtree-negative, with 60% cell viability at 12% (v/v) ethanol. The flocculation level of strain Y197-13 was 8.38%, resulting in its classification as a non-flocculent yeast.

• Applied Biological Chemistry
• /
• v.9
• /
• pp.59-64
• /
• 1968

Takju (Korean native Sake) was mashed with two different materials. One of the material was polished rice and Nuruk(mold wheat), the other one was corn and Nuruk. The amino acids in those fermenting mashes were identified by paper partition chromatography at regular intervals. The results were summarized as follows; a) Following 14 kinds of amino acids were identified in the mash of rice material; lysine, valine, proline, leucine, serine, glycine, aspartic acid, alanine, cystine, tyrosine, histidine, glutamic acid, tryptophan and phenylalanine b) Following 12 kinds of amino acids were identified in the mash of corn material; lysine, valine, proline, leucine, serine, glycine, aspartic acid, alanine, cystine, histidine, argrinine and tryptophan. c) The main amino acids in the Takju mash according to the color density of the each amino acid spot on the paper chromatograms were checked as lysine, valine, leucine, serine, proline and glycine.

• Microbiology and Biotechnology Letters
• /
• v.25 no.2
• /
• pp.203-206
• /
• 1997

Takju is a traditional alcoholic beverage that has been prepared by fermenting the cooked rice and Nuruk (Korean-style bran koji). During fermentation. bacterial contamination is a problem which inhibits the growth of yeast and thus lowers the ethanol production from starch of rice, and causes souring. Major contaminants were known to be gram-positive acid producers at the early stage of fermentation. This problem would be solved if the contaminated bacteria could be controlled. Nisin, a GRAS-grade preservative, was added at the level of 500 iu/g as it retards the growth of the gram-positive bacteria. It was possible to control acid and ethanol production during fermentation. This process increased the ethanol production by 2 % comparing with control.