Korean Traditional Nuruk Research Articles

누룩으로부터 다양한 곰팡이의 선별과 전분 분해 활성을 이용한 동시당화발효

Various fungi were isolated from Korean traditional Nuruk and identified as ten types of fungal strains such as L. corymbifera, L. ramose, S. racemosum, R. oryzae, R. pusillus, M. racemosus, M. circinelloide, A. luchuensis, A. flavus, and A. fumigatus. Among them, four strains (A.fumigatus, A. luchuensis, A. flavus, and R. oryzae) exhibited relatively high glucoamylase activities. When the optimum reaction temperatures were verified for glucoamylase activity, A. fumigatus, A. luchuensis, and A. flavus showed the highest glucoamylase activity at 60℃, and R. oryzae showed the highest glucoamylase activity at 50℃. When simultaneous saccharification and fermentations were performed with yeast, R. oryzae showed the fastest starch degradation rate (1.17 ± 0.10 g/L·h) and the highest ethanol production (17.17 ± 1.46 g/L) for 72 hours.

재래누룩에서 분리한 N4와 N9 효모의 증류식 소주 양조특성

Soju is a Korean traditional distilled alcoholic beverage produced from mashes various crops and Nuruk which is cultured with wild microorganisms. This study was conducted to investigate rice-Soju brewing characteristics of yeasts isolated from Korean traditional Nuruk. The general components of rice (Hanarumbyeo) raw materials were 14.7 g of water, 6.8 g of crude protein, 0.9 g of crude lipid, 0.4 g of crude ash, and 76.5 g of carbohydrate in 100 g. Saccharifying and proteolytic activities in Hanarumbyeo ipguk (solid-state culture of Aspergillus luchuensis) were also determined. The alcohol content of the fermented wash from isolates was 15.37-16.58% (v/v), which is 16.7-36.0% higher than that of industrial yeasts (12.33-13.19%). Reducing sugar contents were 2.04-3.92 and 7.92-8.78 g/100 mL in the isolates and industrial yeasts, respectively. The isolated yeasts showed 25.2-52.7% higher yield of distillates (41% alcohol) compared to industrial yeasts. Forty-one components were detected in the rice distillated Soju (25% alcohol) and principal component analysis revealed differences between the isolated and industrial yeasts with respect to the contents of i-BuOH, isobutanal diethyl acetal, ethyl caprate, and tetradecanoic acid.

Characterization of brewing microorganisms isolated from Korean traditional nuruk for Cheongju production.

The objective of this study was to select and identify yeasts and molds isolated from traditional nuruk and to investigate their brewing characteristics for Cheongju production. The yeast strains Y190 (Accession ID-KACC 93251P), Y263 (Accession ID-KACC 93252P), and Y270 (Accession ID-KACC 93253P) showing high alcohol and flavor productivity were isolated and identified by phylogenetic inference based on an internal transcribed spacer 2 region sequence analysis. In addition, Aspergillus oryzae 83-10 (Accession ID-KACC 93254P) showing the highest enzyme activity was isolated. This study provides basic data for the production of Korean Cheongju and assesses the applicability of these three yeast strains and A. oryzae 83-10 isolated from traditional nuruk.

전통누룩에서 분리한 양조용 곰팡이의 혼합 배양에 따른 품질 특성

We analyzed the mixed culture characteristics of isolated brewing fungi obtained from Korean traditional nuruk for their development as fermentation starters. In a previous study, we selected appropriate fungi strains based on their large fungi bodies and strong enzyme activities. These fungi strains were mixed cultured under various combination of ratios, pHs and temperatures. As a result, total acidities of R. delemar mixed culture media were higher than those of A. oryzae cultured at 20℃ and 37℃. The pHs of A. luchuensis 34-1 and A. oryzae 37-7 as well as R. delemar 58-8 and A. oryzae 37-7 mixed culture media gradually increased with the culture period. On the contrary, total acidities of the mixed culture media gradually decreased. α-Amylase activities of R. delemar 26-4 and R. oryzae 82-7 mixed culture media were strong at 20℃ and pH 4, glucoamylase activities of R. delemar 58-8 and A. oryzae 37-7 were strong at 37℃, pH 3 and 1:2 ratio, and acidic protease activities of R. delemar 26-4 and A. oryzae 78-5 were strong at 20℃, pH 4 and 1:4 ratio. This study provides the optimal mixed culture conditions for fermentation starters based on changes in pH and total acidity, favorable enzyme activities, and fungi varieties.

Characterization of Yeast for Soju (Distilled Spirits) from Korean Traditional Nuruk

본 연구에서는 국내 전통누룩에서 분리한 증류식 소주용 효모의 생리적 특성을 조사하고 동정하였다. 분리균(N4)의 26S rDNA-D1/D2 염기배열은 Saccharomyces cerevisiae 표준균주(NRRL Y-12632)와 100% 상동성을 나타내었고 다극출아에 의해서 증식하였다. Glucose, galactose, maltose, sucrose를 발효할 수 있으며 treha...

Physicochemical properties of Korean rice wine (Makgeolli) fermented using yeasts isolated from Korean traditional nuruk, a starter culture

The applicability of Saccharomycopsis fibuligera CJN1020, Pichia jadinii CJN1287, and Saccharomyces cerevisiae CJN1514 isolated from Korean nuruk, a starter culture, for preparation makgeolli was investigated. These yeasts were suitable for preparation of both white rice makgeolli using a steam method and white rice-brown rice-wheat flour (WBW) makgeolli using a complex method. Upon physicochemical evaluation, there were no differences in the final ethanol concentrations between white rice makgeolli and WBW makgeolli. Differences in final ethanol yields occurred according to yeast species. Final ethanol yields using S. fibuligera and P. jadinii were 16 and 18% using S. cerevisiae. WBW makgeolli samples received higher sensory scores than white rice makgeolli for overall preference. GC/MS analysis revealed higher amounts of aromatic compounds in WBW makgeolli than in white rice makgeolli. The complex method was suitable for preparation of makgeolli using brown rice and wheat flour.

Analysis of Microflora Profile in Korean Traditional Nuruk

A variety of nuruk were collected from various provinces in Korea, and their microflora profiles were analyzed at the species level. A total of 42 nuruk samples were collected and when the viable cell numbers in these nuruk were enumerated, the average cell numbers of bacteria, fungi, yeast, and lactic acid bacteria from all nuruk were 7.21, 7.91, 3.49, and 4.88 log CFU/10 g, respectively. There were no significant differences in viable cell numbers of bacteria or fungi according to regions collected. Bacillus amyloliquefaciens and B. subtilis were the predominant bacterial strains in most samples. A significant portion, 13 out of 42 nuruk, contained foodborne pathogens such as B. cereus or Cronobacter sakazakii. There were various species of lactic acid bacteria such as Enterococcus faecium and Pediococcus pentosaceus in nuruk. It was unexpectedly found that only 13 among the 42 nuruk samples contained Aspergillus oryzae, the representative saccharifying fungi in makgeolli, whereas a fungi Lichtheimia corymbifera was widely distributed in nuruk. It was also found that Pichia jadinii was the predominant yeast strain in most nuruk, but the representative alcohol fermentation strain, Saccharomyces cerevisiae, was isolated from only 18 out of the 42 nuruk. These results suggested that a variety of species of fungi and yeast were distributed in nuruk and involved in the fermentation of makgeolli. In this study, a total of 64 bacterial species, 39 fugal species, and 15 yeast species were identified from nuruk. Among these strains, 37 bacterial species, 20 fungal species, and 8 yeast species were distributed less than 0.1%.

Identification and Characterization of Useful Fungi with α-Amylase Activity from the Korean Traditional Nuruk

The objective of this study was to find useful fungi with α-amylase activity from the Korean traditional nuruk for the quality of traditional Korean alcoholic beverage. In this study, 165 samples of traditional nuruk were collected from 170 regions throughout Korea and the fungi were isolated to a total of 384 strains. In order to investigate the effect of microflora on nuruk, α-amylase activity, saccharogenic power (SP), starch hydrolysis activity and acid producing activity were evaluated. Ten strains were selected by α-amylase activity, which ranged from 458.47 to 1,202.75 U/g. The size of the discolored zone for the starch hydrolysis activity of each fungus ranged from 0.3 to 2 cm. The SP of the 10 strains ranged from 228.8 to 433.4 SP. Of the 10 stains, three were identified as Aspergillus oryzae, two as Aspergillus flavus, two as Lichtheimia sp., one as Rhizopus oryzae and two as other strains. The total aflatoxins present in the nuruks were examined using enzyme-linked immunosorbent assay. The 10 nuruks had less than 1.11 ppb of aflatoxins.