• The Korean Journal of Food And Nutrition
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• v.12 no.4
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• pp.421-426
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• 1999

The major flavor compounds of Takju mash which was brewed with a modified Nuruk made by inocu-lation and cultivation of Rhizopus japonicus T2, Aspergillus oryzae L2 and Hansenula sp. BC26 isolated from Nuruk, were analyzed, as compared with those with current fermenting agents such as commerical Nur-uk and rice koji of Aspergillus kawachii. The contents of isoamyl alcohol isobutyl alcohol and ethyl acet-ate which were known as aroma compounds in Takju were much higher in mash of modified Nuruk than in that of commercial Nuruk or ricd koji. The major organic acids were lactic fumalic and succinic acid in mash of modified and lactic and acetic acid in mash of commercial Nuruk and citric lactic and suc-cinic acid in mash of rice koji. The contents of total organic acids were 5,146mg/L, 1,706mg/L and 1, 388 mg/L in mash of commercial Nuruk rice koji and modified Nuruk respectively. The major free amino acids were glutamic acid alanine proline and histidine in mash of modified Nuruk and glutamic acid proline leucine and histidine in mash of commercial Nuruk and arginine proline and glutamic acid in mash of rice koji. The contents of total free amino acids were 14,090mg/L 12,202mg/L and 7,152 mg/L in mash of modified Nuruk commercial Nurcuk and rice koji respectively. Therefore it seemed that the Takju mash of modified Nuruk was better than that of commercial Nuruk or rice koji.

• Journal of Microbiology and Biotechnology
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• v.22 no.1
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• pp.100-106
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• 2012

In this study, the metabolite profiles of three Aspergillus strains during rice koji fermentation were compared. In the partial least squares discriminant analysis-based gas chromatography-mass spectrometry data sets, the metabolite patterns of A. oryzae (KCCM 60345) were clearly distinguished from A. kawachii (KCCM 60552) and only marginal differences were observed for A. oryzae (KCCM 60551) fermentation. In the 2 days fermentation samples, the overall metabolite levels of A. oryzae (KCCM 60345) were similar to the A. oryzae (KCCM 60551) levels and lower than the A. kawachii (KCCM 60552) levels. In addition, we identified discriminators that were mainly contributing tyrosinase inhibition (kojic acid) and antioxidant activities (pyranonigrin A) in A. oryzae (KCCM 60345) and A. kawachii (KCCM 60552) inoculated rice koji, respectively. In this study, we demonstrated that the optimal inoculant Aspergillus strains and fermentation time for functional rice koji could be determined through a metabolomics approach with bioactivity correlations.

• Korean Journal of Food Science and Technology
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• v.21 no.5
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• pp.721-725
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• 1989

Aflatoxin accumulation by Aspergillus flavus in rice was inhibited by A. kawachii and A. Shirousamii so that the rate of toxin accumulation and the maximum concentration of accumulated aflatoxins were considerablly reduced, although the initiation of aflatoxin accumulation was not affected. The maximal accumulated aflatoxin $B_1$ in rice by A. flavus at $28^{\circ}C$ and 85% RH was $40{\mu}g/50g$ rice after 35 days. Under the same condition but the additional inoculation of A. kawachii, $25{\mu}g\;of\;aflatoxin\;B_1$ was accumulated maximally in 50g rice after 45 days. When A. shirousamii was inoculated simultaneously with A. flavus on rice, however, only trace levels of aflatoxins were detected throughout 60 days of storage. Aflatoxins added to rice were reduced by 97% with A. kawachii and by 98% with A. shirousamii after 7 days during rife koji preparation. They were also reduced after 48 Hours of incubation by 30-67%, with A. kawachii koji and by 16-75% with A. shirousamii koji.

• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.81-85
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• 2004

Quality characteristics of kochujang made with Aspergillus oryzae-and/or Cordyceps sp.-inoculated koji were investigated. Protease activity of Cordyceps sp.-inoculated koji was higher than that of A. oryzae-inoculated one. Sensory evaluation showed that kochujang made with mixture of A. oryzae-and Cordyceps sp.-inoculated koji (70 : 30, w/w) was superior to others.

• 한국균학회소식:학술대회논문집
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• 2014.05a
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• pp.25-25
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• 2014

Koji molds are comprised of yellow, black and white. Black and white koji molds were recently re-visited by this author and it is concluded that they consists of Aspergillus luchuesnsis, A. niger and A. tubingensis, and the most important species for alcoholic beverage production is A. luchuensis. In the case of yellow koji mold, it is comprised of Aspergillus oryzae, A. sojae and A. tamari. In the case of A. sojae, the species is scarcely isolated from nature and rarely used for industry in Korea. Aspergillus tamari is often isolated from traditional Korean Meju, a fermented soybean product, and the classification of the species is clear. However, in the case of A. oryzae, differentiation between A. oryzae and A. flavus is still in controversy. In this study, we collected 415 strains of Aspergillus flavus/oryzae complex from air, rice straw, soybean, corn, peanut, arable soil and Meju in Korea and we examined the aflatoxin producing capacity of the strains. The norB-cypA, omtA and aflR genes in the aflatoxin biosynthesis gene cluster were analyzed. We found that 367 strains (88.4%) belonged to non-aflatoxigenic group (Type I of norB-cypA, IB-L-B-, IC-AO, or IA-L-B- of omtA, and AO type of aflR), and only 48 strains (11.6%) belonged to aflatoxin-producible group (Type II of norB-cypA, IC-L-B+/B- or IC-L-B+ of omtA, and AF type of aflR). In the case of A. flavus/oryzae strains from Meju, almost strains (178/192, 92.7%) belonged to non-aflatoxigenic group and only 14 strains (7.3 %) belonged to aflatoxin-producible group. It is proposed in this study that non-aflatoxigenic strain from Meju is classified as A. oryzae, considering that Meju is food material.

• Applied Biological Chemistry
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• v.2
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• pp.17-21
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• 1961

The manufacture of riboflavine fortified Dwen-Jang has been tried with an exceedingly riboflavine productive Aspergillus oryzae #612 mutant which has been developed by the authors. Both the rice and barley koji of this mutant and Aspergillus sojae have been prepared. Their riboflavine production, saccharifying and protease activities have begin compared The riboflavine fortified Dwen-Jang has been manufactured using the barley koji of riboflavine productive mutant. Their riboflavine content and qualities have been studied comparing with an ordinary Dwen-Jang which has been prepared with the barley kojo of A. sojae strain. The following results have been obtained. (1) The baley koji was superior in riboflavine production and protease activity, inferior in saccharifying ability than rice koji both with A. oryzae #612 and A. sojae. (2) In barley koji, the mutant, A. oryzae #612, produces 1.5 times riboflavine than A. sojae and shows stronger saccharifying and protease activities than the latter. (3) The riboflavine fortified Dwen-Jaug manufactured contained $5.2{\gamma}/g$ of riboflavine, about 1.5 times that of A. sojae. The higher contents of free sugar and free amjno nitrogen have been observed than the ordinary Dwen-Jang manufactured with A. sojae.

• Korean Journal of Food Science and Technology
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• v.17 no.4
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• pp.258-264
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• 1985

The energy for cooking starch prior to saccharification could be saved by fermenting raw starch into ethanol using Aspergillus niger koji of wheat bran. Optimum cultivation time to produce glucoamylase was 4 days in wheat bran medium. The rate of saccharification from uncooked corn starch were optimum at pH 3.3 and 40-$50^{\circ}C$. Corn and sweet potato starch were saccharified more efficiently by wheat bran koji than other tested starch sources. 5 days of fermentation were required for optimum yield of ethanol using a mixture of AspergiUus niger koji and dried yeast. Final ethanol yields from raw corn, sweet potato, and rice starch with agitation at the rate of 100 rpm were about 95% at $30^{\circ}C$.

• The Korean Journal of Food And Nutrition
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• v.6 no.2
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• pp.89-95
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• 1993

A Nuluk, a Korean traditional Koji for brewing, was made with wheat flour and Aspergillus oryzae L2 which had a good aroma and strong abilities In producing saccharogenic and dextrogenic enzymes. The cultural conditions for the production of saccharogenic and proteolytic enzymes were tested. The productivity of dextrogenic enzyme was improved when Nuluk was made with unsteamed wheat flour as compared with steamed one, but that of proteolytic enzyme was reduced. The addition of water containing 0.5% hydrochloric acid was unfavorable for the production of those two enzymes. The optimum ratio of water added to wheat flour for the production of those two enzymes was 28$^{\circ}C$ on the basis of wheat flour, The productivity of saccharogenic enzyme was enhanced when the Nuluk was molded after 20 hours of precultivation, but that of proteolytic enzyme was reduced as compared with no molding. The optimum temperatures for the production of saccharogenic enzyme and proteolytic enzyme were 36$^{\circ}C$ and 28$^{\circ}C$, respectively.

• Food Science and Preservation
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• v.21 no.3
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• pp.434-441
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• 2014

This study investigated the quality characteristics and sensory evaluation of Doenjang samples made of soybean koji and prepared with Bacillus subtillus 3-B-1 and/or Aspergillus oryzae 6-M-1 isolated from traditional Meju, to replace the koji with wheat flour. Among the quality characteristics of doenjang during its fermentation at $30^{\circ}C$ for 40 days, its moisture decreased by degrees, but its amino-type nitrogen and reducing sugar increased by degrees. The color of the doenjang made of koji and prepared with Aspergillus oryzae 6-M-1 changed more significantly than that of the doenjang with Bacillus subtilis 3-B-1. The viable cell and mold counts increased by degrees during the fermentation. The results of the sensory evaluation of the doenjang made with koji and prepared with Aspergillus oryzae 6-M-1 did not significantly differ from those of the doenjang with Bacillus subtilis 3-B-1 and of the commercial doenjang. These results showed the possibility of preparing doenjang with soybean koji instead of wheat flour koji.

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1174-1181
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• 2003

A part of Aspergillus oryzae koji was replaced with Bacillus sp. koji to improve the quality of kochujang, and the resulting effects on enzyme activities, microbial characteristics, and physicochemical properties were investigated during fermentation. The activity of amylase was higher in the kochujang prepared with Asp. oryzae koji. The activity of protease increased as the ratio of Bacillus. sp. koji increased. Viable cell counts of yeast and bacteria of the kochujang increased with increasing ratio of Bacillus sp. koji. The Hunter a-values of the Bacillus sp. koji kochujang were higher, and the degree of increase in the total color difference $({\Delta}\;E)$ was lower in the Bacillus sp. koji group. Consistency and water activity of the kochujang prepared with Bacillus sp. koji was higher, and the pH and titratable acidity of the kochujang also changed slightly. As the ratio of Asp. oryzae koji increased, sugar content decreased. However, the ethanol content of the kochujang did not significantly change. Amino nitrogen content of the kochujang increased, while ammonia nitrogen content decreased as the ratio of Bacillus sp. koji increased. After 12 weeks of fermentation, the result of sensory evaluation showed that C kochujang (75% of Asp. oryzae koji replaced by Bacillus sp.) was more acceptable (p<0.05) than the other groups in taste, color, flavor, and overall acceptability.