• Food Science and Preservation
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• v.21 no.4
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• pp.573-580
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• 2014

The enzymatic activity of Nuruk and the quality properties of Yakju were investigated according to different fungi. The fungi that were used in this study were Aspergillus kawachii KCCM 32819, Aspergillus niger KCCM 32005, Rhizopus japonicus KCCM 11604, Rhizopus oryzae KCCM 11272, Rhizopus oryzae KCCM 11273, Rhizopus oryzae KCCM 11276, and Mucor rouxii KCCM 60148. The study results are as follows. The saccharogenic power of Rhizopus oryzae KCCM 11272 Nuruk was the highest (3,647.72 SP/g) among all the samples. The ${\alpha}$-amylase production and protease activities were highest (3.76 DU and 4.7 tyrosine mg/min, respectively) in the Rhizopus japonicus KCCM 11604 Nuruk. The pH levels of the Yakju made with commercial Nuruk and Rhizopus japonicus KCCM 11604 Nuruk were 4.14 and 4.07, respectively. The total titratable acid content of the Yakju made with Rhizopus oryzae KCCM 11273 Nuruk was the highest (0.56%) among all the samples. Rhizopus japonicus KCCM 11604 and Rhizopus oryzae KCCM 11272 had the highest ethanol yields (15.18% and 15.10%, respectively). In the sensory evaluation carried out in this study, the panel preferred the Yakju made with Rhizopus japonicus KCCM 11604 Nuruk. Overall, however, the panel did not like the Yakju made with Aspergillus niger KCCM 32005 Nuruk.

• The Korean Journal of Food And Nutrition
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• v.9 no.3
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• pp.336-340
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• 1996

Rhizopus japonicus had the highest chitosan productivity compared with the chitosan productivity among Rhizopus sp. strains. To increase the productivity of microbial chitosan from Rhizopus faponicus, production medium and incubation conditions were optimized. The composition of the medium and the incubation conditions were as follows : starch 2%, yeast extract 2.5%, KH2PO4 0.05%, MgSO4 0.01%, FeSO4 0.002%, MnSO4 0.002%, ZnSO4 0.002%, CaC12 0.002%, PH 5.5, incubation temperature medium compared with chitosan productivity.

• The Korean Journal of Food And Nutrition
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• v.8 no.1
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• pp.6-12
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• 1995

The purpose of this study was to examine the aptitude of wheat flour-Nuluks, for Takju brewing, which were made with Aspergillus oryzae, Rhizopus japonicus or Aspergillus usamii mut. Shirousamii, and to know the way of effective use the Aspergillus oryzae-Nuluk showed high saccharogenic activity, and Rhizopus japonicus-Nuluk high proteolytic activity. When these two Nuluks were combined, the activities of saccharogenic amylase and protease were more balanced. The Takju mash of Aspergillus oryzae-Nuluk was high in acidity and in amino acidity, and that of Rhizopus japonicus-Nuluk high in the content of free sugar, but, that of Aspergillus usamii mut. Shirousamii-Nuluk was low in amino acidity, free sugar and ethanol content. The Takju of Rhizopus japonicus-Nuluk was high in the content of suspended solid and slow in its sedimenting rate, but that of Aspergillus usamii mut. Shirousamii-Nuluk was not. The Takju which was made with combined use of Aspergillus oryzae-Nuluk and Rhizopus japonicus-Nuluk was more balanced in the composition of flavoring ingredients, and was slow in sedimenting rate of suspended solid. Moreover, it gained good result in sunsory evaluation test.

• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.555-562
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• 1997

The characteristics of mash qualities of takju prepared by using different nuruk (Korean-style bran koji) such as Mucor racemosus nuruk, Rhizopus japonicus nuruk, Aspergillus oryzae nuruk, Aspergillus kawachii nuruk and traditional nuruk were investigated during fermentation. At the begining of fermentation, ethanol content was in the range of $2.0{\sim}3.0%$. However, it increased to $8.2{\sim}12.6%$ after 16 days of fermentation. Takju made from Rhizopus japonicus nuruk showed higher ethanol content than treated otherwise. pH of takju made from Rhizopus japonicus nuruk showed higher value the others. Total acids were $0.15{\sim}0.20%$ at the begining of fermentation, and it increased to $0.086{\sim}1.57%$ after 16 days of fermentation. Total sugar were $16.64{\sim}17.62%$ at the begining of fermentation, but decreased to below 7.00% after 16 days of fermentation. Rhizopus japonicus nuruk showed the lowest level of total sugar content. Except ethanol, iso-amyl alcohol and iso-butyl alcohol were major part of minor alcohol in the mash of takju. Higher concentration of iso-amyl alcohol, iso-butyl alcohol and n-propyl alcohol were found in the mash of Rhizopus japonicus nuruk whereas the level of phenylethyl alcohol was high in the mash of traditional nuruk. Fusel oil was $0.002{\sim}0.411\;mg/mL$ during fermentation.

• Microbiology and Biotechnology Letters
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• v.16 no.6
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• pp.438-442
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• 1988

The enzyme produced by Rhizopus japonicus was able to convert selectively ginsenoside-Rb$_1$which is the most abundant ginseng saponin, into ginsenoside-Rd which was known to be superior to ginsenoside-Rb$_1$pharmaceutically. The convertible enzyme was purified homogeneous from wheat bran culture of Rhizopus japonicus by ammonium sulfate fractionation and column chromatography of TEAE-cellulose, DEAE-Sephadex A-50, Sephadex G-150, Sepharose 2B. Specific activity of the purified enzyme was increased to a bent 96 folds and yield was appeared to be 11% of culture extract. Evidence for homogenity was obtained from polyacrylamide and SDS-polyacrylamide gel electrophoresis. Molecular weight of the enzyme was estimated about 88, 000 daltons by Sephadex G-l50 gel filtration and SDS-polyacrylamide gel electrophoresis, and it did not consist of any subunit.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.1
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• pp.157-162
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• 1996

A. oryzas 의 밀가루 누룩과 R. japonicus의 밀가루 누룩으로 탁주를 제조할 때에는 두 누룩의 혼합 비율이 탁주의 품질에 미치는 영향을 알아조기 위하여 두 누룩의 혼합 비율을 달리하여 7종의 탁주시료를 제조하고, 탁주의 이화학적 및 관능적 특성들을 조사하였다. R. japonicus는 누룩의 사용 비율이 높을 때에는 술덧의 산도와 유리당 함량이 높았고, 제성주의 부유물 함량과 부유물의 현탁 안정성도 높았다. 그러나 A. oryzas 누룩의 사용 비율이 높을 때에는 술덧의 산도와 유리당 함량이 낮았고, 제성주의 부유물 함량과 부유물의 현탁 안정성도 낮았다. R. japonicus 누룩과 A. oryzas 누룩을 2 : 1~5 : 1의 비율로 병용했을때에는 주박의 양이 크게 줄어들었고, 아미노산 함량이 증가하였으며, 기호성도 더 좋아졌다. 탁주의 전반적이 특성으로 볼 때 각 누룩의 단용시에는 R. japonicus 누룩이 A. oryzas 누룩보다 좋았다. 그러나 R. japonicus 누룩과 A. oryzas 누룩을 병용했을때에는 탁주의 전반적인 품질이 더욱 개선되어졌는데, 이때 두 누룩의 최적 혼합 비율은 대략 5 : 1이었다.

• The Korean Journal of Mycology
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• v.17 no.1
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• pp.31-34
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• 1989

In ginseng saponin, $ginsenoside-Rb_1$ was contained the most abundantly. But ginsenoside-Rd which is similar to ginsenoside $Rb_1$ in structure was known to be superior to $ginsenoside-Rb_1$ pharmaceutically. A strain of Rhizopus japonicus is able to produce the convertible enzyme which can convert selectively $ginsenoside-Rb_1$ to ginsenoside-Rd without the change of any other ginsenoside. The strain can produce the most enzyme after 5 day-culture on wheat bran medium. The enzyme production was promoted best efficiently by addition of red ginseng powder in ginseng products, xylose in sugars, laminarin in polysaccharides, naringin in flavonoids, and potassium nitrate in nitrogen substrates.

• Korean Journal of Microbiology
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• v.20 no.3
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• pp.134-146
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• 1982

This experiment was designed to elucidate the life cycle of 7 species (Rh.nigricans, Rh. delemar, Rh.oryzae, Rh.acidus, Rh.tritici, Rh. formosaensis and Rh. japonicus) in genus Rhizopus isolated from Korean soil, so as to seize the appropriate stage for detecting their chromosomal number and nuclear size under the method of thin layer slide culture using modified Rogers(1965a) medium. The results are summarized as the folowings ; 1. The haploid chromosome number are found 16 in Rh. japonicus are 8, respectively. 2. Comparing the 7 species of Rhizopus with each other, it may be concluded that the basic haploid chromosome number of genus Rhizopus distributed in Korean soil are 8 and that Rh. nigricans is double of the basic hapolid chromosome number (n = 16). Besides them, the other two species (Rh. tritici and Rh. formosaensis) are believed aneuploids.

• The Korean Journal of Food And Nutrition
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• v.6 no.2
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• pp.96-102
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• 1993

A Nuluk, a Korean traditional koji for brewing, was made with wheat flour and Rhizopus japonicus T2 which had a good aroma and strong abilities in producing saccharogenic and proteolytic enzymes, and cultural conditions for the production of those two enzymes were tested. The productivity of saccharogenic enzyme was markedly improved when Nuluk was made with unsteamed wheat flour as compared with that with steamed one, but that of acid protease was reduced. The addition of water containing 0.5% hydrochloric acid was unfavorable for the production of saccharogenic enzyme and neutral protease. The optimum ratio of water added to wheat flour for the production of saccharogenic enzyme and proteolytic enzyme was 28% on the basis of wheat flour. The productivity of saccharogenic enzyme was enhanced "when the Nuluk was molded after 10~20 hours precultivation but that of proteolytic enzyme was reduced as compared with no molding. The optimum temperature for the production of saccharogenic enzyme was 28f and that of proteolyic enzyme was also 28$^{\circ}C$. The optimum cultural time for the production of saccharogenic enzyme was 36 ~72 hours at 3$0^{\circ}C$ and that of proteolytic enzyme was 36 hours.ours.

• The Korean Journal of Food And Nutrition
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• v.10 no.4
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• pp.491-496
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• 1997

To increase the productivity of microbial chitosan from Rhizopus oligosporus ATCC22959, production medium and incubation conditions were optimized. The composition of the medium and the incubation conditions were like follows : starch+glucose(1:1) 3.0%, yeast extract 3.0%, KH2PO4 0.05%, MgSO4 0.01%, ZnSO4 0.002%, pH 5.0, incubation temperature 3$0^{\circ}C$, and incubation time 96hours. The productivity of chitosan of optimized medium was about 6.4 times higher than that of basal medium.