• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.4
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• pp.369-375
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• 2018

This study investigated the effects of selected seaweeds on rice koji preparation (rice inoculated with Aspergillus luchuensis) and enzyme activity. Four types of rice koji were prepared using one of three seaweeds (0.5% laver, 0.5% kelp and 0.5% green laver) or a control for 72 h. The changes in the moisture content, water activity, pH, total mold cell count, amylase and protease activities were measured. During preparation, there was no significant difference in the moisture content among the four kojis, whereas the pH in the kojis made with either laver or green laver decreased rapidly compared with the control (P<0.05). This seemed to result from the seaweeds promoting the growth of mold cells. In terms of the activities of both amylase and protease, the koji with laver was superior. Subsequently, the amylase and protease activities of the koji made with laver were evaluated at various pHs (3 to 9), temperatures ($15-55^{\circ}C$) and NaCl concentrations (0-10%). The activities of both enzymes decreased notably at pH 9 and the protease activity decreased at temperatures above $45^{\circ}C$. Although the activities of both enzymes decreased at greater than 2.5% NaCl, activity was present at 10% NaCl.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1979.10a
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• pp.243.2-243
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• 1979

현재 우리나라의 탁약주 용 Rice-Koji 제조 용종국균으로 널리 분양되고 있는 분양되고 있는 fawachi, S-27 균주가 생성하는 Amylase의 효소학적 특성과 Rice-Koji i제조 시 유기산 및 당화 효소의 생성 조건을 검토했다. 1. 본 균은 유기산 생성력이 강하고 또 생성하는 당화효소 및 액화효소는 내산성이 극히 강하며 pH3~5의 범위내에서 최고 활성을 나타내었으므로 탁약주 제조 용 종국균으로 아주 적합하였다. 2. 본 균의 발아 최적온도는 36$^{\circ}C$이었으며 Rice -Koji제조시 제국시간을 40시간으로 볼 때 유기산 생성의 최적온도는 32$^{\circ}C$이었고 당화효소 생성의 최적온도는 36$^{\circ}C$이었으며 고온인 4$0^{\circ}C$에서는 유기산 생성이 극히 불량하였다. 3. Rice-Kojiw제조시 당화효소의 생성은 배지의 수분함량 35%일 때 최고치를 보였으며 유기산 생성은 이 보다 높은 조건인 수분함량 40%일 때 이었고 비교적 건조한 조건인 수분함량 30%일 때는 유기산 생성이 특히 불량하였다. 4. 배지의 두께가 3cm이상이 되면 유기산 및 당화효소 생성에 않은 지장을 주었다. 5. 종국균의 점종량은 유기산 및 당화효소의 생성에 별로 영향을 미치지 못했다.

• Applied Biological Chemistry
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• v.39 no.1
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• pp.9-15
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• 1996

To improve the quality of Choungju. a kind of rice wine, two different types of koji were prepared and compared : one from wheat bran with Aspergillus usamii mut. shirousami Y-79 and the other from rice with A. oryzae, and yeast strains from cereal wine mashes were newly isolated and applied for the brewing method. Levels of the related enzymes such as glucoamylase, ${\alpha}-amylase$ and acid protease in the wheat bran koji were higher than those in the rice koji, whereas vice versa in the case of acid carboxypeptidase. An amount of $2{\sim}3%$ wheat bran koji to the weight of total rice was adequate for saccharification of the mash and resulted in improved duality of the fermented mash, accompanied by decrease in koji ordor and amino acidity. When the solution of wheat bran koji and the isolated yeast strains were employed, the better Choungju taste was obtained in comparison with those fermented with Japanese sake yeasts, the strain K-7 and 9, due to the lower content of organic acids especially succinic acid. The amino acidity of the fermented mash was able to be controlled to some extent, when the rico types of koji and the isolated strains were employed, by changing the ratio of the two koji types. However, the application of the rice koji with the isolated strains was not desirable for the brewing process because organic acids were produced in excess and ethanol fermentation was retarded.

• Food Science and Preservation
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• v.18 no.6
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• pp.859-868
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• 2011

This study was conducted to determine the appropriate mixing ratio of Koji and rice Doenjang. Brown rice Doenjang (BR) was prepared with three different ratios of cooked soybean to brown rice Koji [1.5:1 (BR-1); 2:1 (BR-2); and 3:1 (BR-3)], and polished-rice Doenjang (PR) was prepared with cooked soybean and polished-rice Koji (2:1). The components related to the quality of Doenjang were analyzed during 60-day aging. No significant differences were found in the moisture and salt contents between the brown rice Doenjang and the polished-rice Doenjang. The pH, titratable acidity, and bacteria cells increased at 20-30 days aging time, and decreased thereafter. The reducing-sugar and ethyl alcohol contents, on the other hand, increased at 10-20 days previously. These analytical values of the physicochemical and microbiological characteristics increased with the increase in the percentage of koji in each Doenjang. The amino-nitrogen and free-amino-acid contents showed the highest levels in BR-1: 887.6 and $4047.0{\pm}1.5$ mg%, respectively. The ${\gamma}$-aminobutyric-acid (GABA) contents slightly increased with increasing aging time. In the color of Doenjang, the lightness and yellowness increased along with the aging time, but the redness decreased as the aging time increased. These results showed that BR-1 processed the fermentation the fastest compared with the others. Moreover, the reducing-sugar, ethanol, and free-amino-acid contents as palatable components increased rapidly until 30 days aging time.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.1
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• pp.149-154
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• 2016

Cosmeceutical potentials of unpolished rice vinegars containing different amounts of Monascus-fermented soybean powder (soy-koji) were investigated. Four different vinegar types were prepared using 0, 10, 30, and 50% soy-koji addition. Soy-koji vinegar showed stronger cosmeceutical properties, in terms of tyrosinase and elastase inhibitory activities as well as antioxidant capacities, than unpolished rice vinegars (P<0.05). Bioactive effects of soy koji vinegar increased with increasing concentrations of total phenolics and isoflavone aglycones (P<0.05). Results indicate that unpolished rice vinegar supplemented with soy-koji can be an efficient strategy to improve bioactivities in vinegar with associated enhancement of cosmeceutical functionality.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5384-5393
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• 2015

We investigated the effects of milling degrees of rice on characteristics of the steamed rice and fermentation of rice koji as a raw material of cheongju. It was studied for 8 months about ratio of water absorption and koji charateristics according to milling degrees. The The more increasing rice milling, the less the protein contents of milled rice was continuously decreased and the lipid and ash contents were sharply decreased to until the milling degrees 20%, and then gradually decreased. When steeping the milled rice, higher milling degrees raised rapid water asorption and higher maximum water asorption, lower water temperature raised gradual water absorption and higher maximum absorption. The longer steeping time, the steamed rice milling degrees 40% showed significantly lower hardness and springness than others. Alcohol contents of the fermented mash with rice koji milling degrees 10% was lower with 16.3-16.9%(v/v) than other sample's 17.1-17.5% (v/v). The total acid contents showed that the milling degrees 10% indicated the lowest content(0.71-0.76%) and the milling degrees 30% indicated highest content(0.93-0.99%). Within the same milling degrees, As the steeping time increases, the total acid contents imcrease. In conclusion, the milling degrees influenced on physicochemical chatacteristics of rice and steamed rice condition.

• 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.

• 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.45 no.1
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• pp.70-76
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• 2013

The aim of this research was to analyze makgeolli with nineteen kinds of rice and koji. Among 19 rice, 18 rice were domestic products and one rice was an import. For the properties of koji made with 19 kinds of rice, the acidity was over 5.0 and the saccharogenic power was more than 60SP. Makgeolli brewed with 19 kinds of rice and the koji of each rice were analyzed for alcohol contents, pH, total acidity and solid contents during fermentation. After fermentation, raw liquor's alcohol degree was set 6.0%, the pH ranged 3.47-3.76, the total acidity 0.27-0.44%, the solid contents and the reducing sugar were $2.7-4.6^{\circ}$Bx and 2.49-6.01 mg/mL. Organic acid was detected 5 kinds (oxalic, malic, lactic, acetic, succinic acid) and free sugars were found such as glucose, maltose and fructose. Hwayoung, Hopum and Sura were higher than the residue in 15 kinds of rice in the preference test.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.11
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• pp.1617-1622
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• 2011

We conducted this study to investigate the quality characteristics of saccharified rice gruel prepared with different cereal koji mold (rice, buckwheat, sorghum, adlay, or Italian millet koji). The moisture, crude protein, crude lipid, and crude ash content of rice, buckwheat, sorghum, adlay, and Italian millet showed a range of 11.12~12.85, 5.81~16.24, 0.56~4.36, and 0.28~1.93%, respectively. The proximate composition of saccharified rice gruel prepared with different cereal koji was significantly (p<0.05) higher than unsaccharified rice gruel. The pH, L, a, and b values of saccharified rice gruel ranged between 6.09~6.39, 60.38~78.25, -0.87~5.70, and 7.74~13.37, respectively. The viscosity of saccharified rice gruel prepared with different cereal koji was significantly (p<0.05) lower than the unsaccharified rice gruel. After saccharification, the soluble solids, glucose, and maltose content of saccharified rice gruel prepared with different cereal koji were significantly increased in the range of 11.47~13.03$^{\circ}Brix$, 0.60~1.44%, and 0.47~0.88%, respectively. A sensory evaluation indicated that saccharified rice gruel was significantly (p<0.05) better than unsaccharified rice gruel. In conclusion, cereal koji could be used as a gruel processing method to increase the sensory properties and nutritional values of gruels.