• Microbiology and Biotechnology Letters
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• v.26 no.5
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• pp.456-464
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• 1998

For the standardization and quality improvement of traditional Korean Nuruk, 10 strains of fungi, which were isolated from Nuruks and showed good productivity of the saccharogenic and dextrinogenic enzymes, acid and flavor, were selected and their enzymological characteristics and identification were carried out. Aspergillus spp. and Rhizopus sp. showed a high liquefying activity without regard to cultivation time, whereas the majority of strains except for Rhizopus sp. had decreasing saccharifying activity in proportion to the increase in cultivation time. Aspergillus spp. No.17-2, No.17-6 and Rhizopus sp. No.18-1 showed high liquefying and saccharifying activity after 15 and 30 day cultivation. The optimum temperature of most of these saccharogenic and dextrinogenic enzymes was from 40$^{\circ}C$ to 60$^{\circ}C$, and their optimum pH was extensive between pH 3 and pH 11. But Penicillium spp.(2 strains) and Rhizopus sp. showed low activity under the alkalic and acidic conditions. Among these isolated strains, 5 strains which had shown the high productivity of materials were identified as Aspergillus oryzae NR3-6 and Aspergillus oryzae NR17-6, Aspergillus penicilloides NR12-1, Penicillium expansum NR7-7 and Rhizopus oryzee NRl8-1, respectively. Five kinds of mixed culture were carried out and all of them showed a better productivity of saccharogenic and dextrinogenic enzymes than single culture. These results indicate that it is possible to make traditional Korean liquors of good quality by using these fungi.

• Microbiology and Biotechnology Letters
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• v.41 no.2
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• pp.168-175
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• 2013

In this study we investigated the possibility of preparing brewed brown rice makgeolli, a traditional Korean rice wine, under diverse conditions. For this purpose the physicochemical characteristics of makgeolli brewed at different temperatures, utilizing a variety of nuruks, the traditional Korean fermentation agent, were studied. The alcohol content was seen to be highest when brewing occurred at $30^{\circ}C$, with the nuruk TN producing 16.2%. At $20^{\circ}C$TN produced 14.1% alcohol content. The alcohol content was therefore higher, by about 2%, for $30^{\circ}C$ fermentations than $20^{\circ}C$ fermentations. Similarly, saccharifying activity was influenced by temperature and sugar content, with a higher activity seen at $30^{\circ}C$ than at $20^{\circ}C$. As the fermentations progressed acidification petered out, with titratable acidity being 0.50-0.67% in all end samples. On the Hunter L, a, b scale; the a value decreased slightly, while the b value increased steadily during the fermentation process. Measurements of total organic acids were highest at $30^{\circ}C$, with the nuruk AK, at about 550 mg%. The content of citric acid was the highest at $30^{\circ}C$, being 230-310 mg% in all samples. However, more lactic acid was detected at $20^{\circ}C$ than at $30^{\circ}C$. Total free amino acid was highest at $30^{\circ}C$, with TN at $8,605{\mu}g/ml$, AK at $6,083{\mu}g/ml$, and RJ at $2,381{\mu}g/ml$. Total free amino acid and essential amino acid was shown to be higher at $30^{\circ}C$ than at $20^{\circ}C$. The bioactive substance ${\gamma}$-aminobutyric acid was also higher at $30^{\circ}C$, with TN at $223{\mu}g/ml$. From all of these results, we surmise that brown rice makgeolli manufacturing conditions are optimal at $30^{\circ}C$ fermentation temperatures and using the nuruk TN for brewing vinegar. In addition, the nuruk used clearly affects the quality of brown rice makgeolli and an appropriate method to determine the best nuruk for various purposes should be pursued.

• KSBB Journal
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• v.30 no.6
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• pp.283-290
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• 2015

In this study was selected the cellulolytic microorganism and investigated optimum condition of cellulase production for the cellulosic bioethanol production. A bacterial strain Paenibacillus jamilae BRC15-1, was isolated from soil of domestic reclaimed land. For optimizing cellulase production from the selected strain, various culture parameters were investigated such as culture medium, pH (pH 4~10), temperature ($25{\sim}50^{\circ}C$) and culture time (2~72 h). As a result, P. jamilae BRC15-1 efficiently produced cellulase from cellulosic biomass under following conditions: 24 h of culture time (pH 7, $40^{\circ}C$) in manufactured media of CMC (carboxymethyl cellulose) with peptone. Optimum saccharifying condition of crude enzyme produced from P. jamilae BRC15-1 was identified on pH 6 and $40^{\circ}C$ of reaction temperature, respectively. This crude enzyme from P. jamilae BRC15-1 was used for saccharification of pretreated sweet sorghum (Sorghum bicolor var. dulciusculum Ohwi) bagasse under the optimal condition. Finally, pretreated sweet sorghum bagasse including 0.1 g of glucan was saccharified by crude enzyme of P. jamilae BRC15-1 into 2.75 mg glucose, 0.79 mg xylose and 1.12 mg arabinose.

• Korean Journal of Food Science and Technology
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• v.49 no.2
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• pp.132-140
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• 2017

Nuruk, a traditional Korean alcoholic beverage starter, was evaluated as an additional saccharifying agent comprising up to 1.5% (w/w) of malt weight in ale-type beer processing. Sample characteristics were monitored during fermentation, ripening, and storage. Beer containing nuruk showed higher numbers of total viable bacteria and yeast cell counts. Additionally, ethanol (6.19-6.35%), color (Standard Reference Method), foam stability ($228.49-368.24{Sigma}$), saccharogenic power (307-417), and reducing sugar (3.83-5.25%) increased as the amount of nuruk was increased, while viscosity (3.13-2.07 cP) and bitterness unit (19.68-13.13) were lower than in samples without nuruk. Overall acceptance and aftertaste of the beer were significantly higher in a preference test. These results demonstrate that nuruk can be used to produce a new type of ale.

• Applied Biological Chemistry
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• v.44 no.2
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• pp.88-91
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• 2001

Mixtures of rice and sweet persimmons to make sweet syrup, jochung, were saccharified by barley malt. Soluble solid contents, reducing sugar and free sugar contents, and sensory quality were determined in jochungs, which were prepared from various ratios (10 : 0, 7 : 3, 5 : 5, 3 : 7) of rice to sweet persimmons. Amylase activity had the highest value, 10466 Unit, after 3 hrs during saccharification process at $55^{\circ}C$. In HPLC determination of free sugars, maltose in saccharifying liquids found the highest amount followed by fructose and glucose. With increasing amounts of sweet persimmons, fructose and glucose contents increased while maltose content decreased. The soluble solid contents reduced as the sweet persimmons proportions increased. The control group without sweet persimmons showed highest value, $58^{\circ}Brix$, in soluble solid content. There appeared to be a slight decrease in reducing sugar and free sugar contents as proportion of sweet persimmons increased. Jochung prepared at high amounts of sweet persimmon had better scores in overall acceptance.

• Applied Biological Chemistry
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• v.42 no.4
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• pp.324-329
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• 1999

Barley malts were prepared at 15, 18 and $21^{\circ}C$ for $3{\sim}6$ days, and assayed for ${\beta}-glucanase$, ${\alpha}-amylase$ and ${\beta}-amylase$ activities. ${\beta}-Glucanase$ activity increased markedly during earley germination and reached maximum at the 6th day of germination. ${\beta}-Glucanase$ activity in six-rowed barley malt was much higher than that in two-rowed malt. ${\beta}-Glucanase$ activity was associated with reduction in ${\beta}-glucan$ content during germination. ${\beta}-amylase$ activity was also considerably higher in two-rowed barley, and increased continuously during 6-day germination. ${\beta}-Amylase$ activity was the lowest at $15^{\circ}C$, the highest at $18^{\circ}C$, and intermediate at $21^{\circ}C$ of germination temperature. Considerable amount of ${\beta}-amylase$ was detected in ungerminated raw barley, and this enzymatic activity tended to increase during 6-day germination. Diastatic power, measure of starch-saccharifying enzyme, in six-rowed malt was $1.4{\sim}1.6$ fold higher than in two-rowed malt. Germination at $18^{\circ}C$ for $5{\sim}6$ days was suggested to be the optimum condition for manufacturing good quality malts, in terms of enhanced starch-degrading enzymatic activity.

• Microbiology and Biotechnology Letters
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• v.7 no.1
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• pp.37-46
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• 1979

In order to investigate the compositional change of the lauan and pine sawdust media during the coltivation of oyster mushroom (Pleurotus ostreatus) chemical components of the two media and mushroom were analized periodically from spawning to ending. The results are summerized as follows: 1) The total yield of mushroom from the lauan sawdust media was 6.39 kg/$m^2$, and from the Pine saw-dust media 6.31 kg/$m^2$, 94％ of which was produced from the first and second cropping period. 2) In both media ash content increased gradually, while organic matter content decreased as the cultivation progressed. Moisture content, which was about 79％ at the time of spawning, decreased a little during the priod of mycelial propagation, after which no change was observed. 3) Total nitrogen content of the two media decreased gradually as the cultivation progressed, and total loss of insoluble nitrogen was greater than that of soluble nitrogen. Amino nitrogen content tended to increase continually. 4) In both media pentosan, $\alpha$-cellulose, lignin and C/N ratio decreased gradually, while the content of reduced sugar, trehalose and mannitol continued to increase. 5) In both media phosphorus, potassium, manganese and zinc decreased, and magnecium, calcium, iron and copper showed irregular changes. 6) CMC-saccharifying and liquefying activity gradually increased from after mycelial propagation to the second cropping, after which it decreased in both media. Xylanase activity rapidly and greatly increased during the second cropping period rather than the first period. At the start of the third cropping period the activity decreased slowly. Protease activity was highest after mycelial propagati, after which it gradually decreased. The pH of the two media decreased as the cultivation progressed. 7) In both media little change was observed in the content of the components of mushroom cropped from the first to the third period, but slight decrease was noticed at the fourth cropping.

• Journal of Microbiology and Biotechnology
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• v.24 no.12
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• pp.1664-1672
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• 2014

In this study, a fibrous bed bioreactor (FBB) was used for $\small{D}$-lactic acid ($\small{D}$-LA) production by Sporolactobacillus inulinus Y2-8. Corn flour hydrolyzed with ${\alpha}$-amylase and saccharifying enzyme was used as a cost-efficient and nutrient-rich substrate for $\small{D}$-LA production. A maximal starch conversion rate of 93.78% was obtained. The optimum pH for $\small{D}$-LA production was determined to be 6.5. Ammonia water was determined to be an ideal neutralizing agent, which improved the $\small{D}$-LA production and purification processes. Batch fermentation and fed-batch fermentation, with both free cells and immobilized cells, were compared to highlight the advantages of FBB fermentation. In batch mode, the $\small{D}$-LA production rate of FBB fermentation was 1.62 g/l/h, which was 37.29% higher than that of free-cell fermentation, and the $\small{D}$-LA optical purities of the two fermentation methods were above 99.00%. In fe$\small{D}$-batch mode, the maximum $\small{D}$-LA concentration attained by FBB fermentation was 218.8 g/l, which was 37.67% higher than that of free-cell fermentation. Repeate$\small{D}$-batch fermentation was performed to determine the long-term performance of the FBB system, and the data indicated that the average $\small{D}$-LA production rate was 1.62 g/l/h and the average yield was 0.98 g/g. Thus, hydrolyzed corn flour fermented by S. inulinus Y2-8 in a FBB may be used for improving $\small{D}$-LA fermentation by using ammonia water as the neutralizing agent.

• Korean Journal of Food Science and Technology
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• v.45 no.3
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• pp.333-338
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• 2013

Enzymatic activity in germinated cereal grains is important for the saccharification of starch materials. This study was conducted to investigate the amylolytic activities of germinating brown rice and black rice that have different amylose contents. Brown rice and black rice were steeped at room temperature for 24 h and germinated at 20 and $30^{\circ}C$ for 1, 2, and 3 days. ${\alpha}$- and ${\beta}$-Amylase activities in normal brown rice increased very slightly during the 3-day germination period, but the enzymatic activities were slightly higher in low-amylose (waxy type) brown rice. Diastatic power (DP), a measure of starch-saccharifying enzyme, was higher in the germinating brown rice with low amylose than in those with normal amylose content. ${\alpha}$- and ${\beta}$-Amylase activities in black rice increased gradually during germination, and DP of low-amylose black rice appeared to be higher than that of normal brown rice. Amylase activities in brown rice and black rice germinated at $30^{\circ}C$ were higher than those germinated at $20^{\circ}C$. Compared to brown rice, the overall amylolytic activity of germinated black rice was observed to be higher than that of brown rice.

• Korean Journal of Food Science and Technology
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• v.16 no.4
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• pp.463-471
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• 1984

For the eventual alcohol production from uncooked starch, an efficient saccharification process was examined by using the combined action of steeping, pectin depolymerase, ${\alpha}-amylase$ and glucoamylase. The total sugar content of rice, sweet potato and tapioka used were 4.53, 4.26, and 3.92 mmole/g sample. $70\;{\pm}\;10%$ of the total sugar was hydrolyzed when cooked starch was saccharified under the condition which is currently used in industry. The smaller starch particle was used, the more saccharification was obtained. Efficient saccharification was obtained by treatment with 5% $H_2SO_4$ (sample: working volume = 1:2) at $60^{\circ}C$ for 12 hr. Optimization was carried out for the saccharification of uncooked starch by the combined action of pectin depolymerase, ${\alpha}-amylase$, and glucoamylase. The conditions are: pectin depolymerase; pH 4.5, $45^{\circ}C$, 2 hr, ${\alpha}-amylase$; pH 6.0, $60^{\circ}C$, 1 hr, and glucoamylase; pH 3.5, $60^{\circ}C$, 1 hr. Simultaneous treatment of the combined action of macerating, liquifying and saccharifying enzymes yielded better result than stepwise treatment of 3 enzymes. Degrees of saccharification of uncooked tapioka, rice and sweet potato were 82, 90.5, and 84.5%, respectively on the basis of total sugar, under the optimized conditions.