• Korean Journal of Food Science and Technology
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• v.26 no.1
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• pp.6-11
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• 1994

A cyclodextrin glucanotransferase(CGTase)-producing Bacillus sp. I-5 was isolated from soil and the enzyme exhibited the maximum reaction rate at pH 8.0 and $50^{\circ}C$. It was found that CGTase of I-5 produced ${\beta}-$ and ${\gamma}-CD$ mainly but the production ratio of cyclodextrins (CDs) was influenced by the buffer solution. Sodium acetate significantly stimulated the formation of ${\gamma}-CD$, increasing the content by 35%. The production of CDs was influenced by DE value of starch. The results indicated that DE value in the range of $3.5{\sim}6.0$ were most effective for the CD formation. CGTase was immobilized on the reversibly soluble-insoluble carrier, hydroxypropyl mothylcellulose acetate succinate. The immobilized CGTase was soluble at pH 7.5, and precipitated easily at pH 6.0. Enzyme reactor was designed to produce CD continuously. It was composed of three major stages-CD produttion by immobilized CGTase, conversion of the residual dextrin to glucose by amylase and glucoamylase and alcohol fermentation by yeasts to remove the glucose into alcohol. The yield of total CDs was 3.65g from 10g soluble starch.

• Korean Journal of Food Science and Technology
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• v.2 no.1
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• pp.67-71
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• 1970

The amylase was0 incubated in a 9mm hole on the starch agar gel plate bored with a cork borer. When 0.1N-iodine solution sprayed on the plate, the formed uncolored zone were observed. An activity of amylase has been determined by measurement of diameter of the uncolored zone. We named this method 'cork borer method'. When amylase was incubated on the starch agar gel plate, the following points were obtained. 1) The optimum pH for the formation of the zone in case of amylases(Biotex, Spitase) which produced by Bacillus is neutrality and alkali, while that for Glucoamylase, Biodiase, and Mucorrennin which produced by Rhizopus and Mucor is from 5 to 7. 2) The diameter of the zone was increased by the incubation time and amylase activity. 3) The zone was easily formed at low level of starch concentration and was formed much bigger than at $50^{\circ}C\;than\;at\;10^{\circ}C$. From the above results, after malting the starch agar gel plate, keeping constant concentration of the starch, the measurement of amylase activity is in efficiency upon the constant reaction time and temperature.

• Korean Journal of Microbiology
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• v.20 no.3
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• pp.125-133
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• 1982

Mutational experiments were performed to imporve the cellulase productivity of Aspergillus phoenicis KU175, isolated from the southern part of Korea, as a high cellulase producer. By treatment ultra-violet light nad 4-NQO(4-Nitroquinoline-N-Oxide), mutation waas induced, and treatment ultra-violet light and 4-NQO (4-Nitroquinoline-N-Oxide), mutation was induced, and A.phoenicis KU175-115 was finally selected for its highest avicelase production. Avicelase production of the mutant was increased about 2 times compared with those of the wild strain. However, activities of other hydrolytic enzymes, such as amylase, protease and nuclease, of the mutant strain didn't show a marked difference compared with those of the nuclease, of the mutant strain didn't show a marked difference compared with the wild strain, except slight increase in ribonuclease activity and slight decrease in glucoamylase activity. Avicelases from the mutant strain selected were purified from wheat bran culture by successive salting out, followed by dialysis and column chromatography, and their charcteristics were compared with thosw of the wild strain. Avicelase was separated into three peaks in the mutant strain as well as in the case of wild strain. Avicelase II activity of the mutant strain was prominently higher than that of the wild strain, while avicelase I and III activities of those were equivalent. The optimal pH ranges and stability of avicelase II from the mutant strain were pH4-5 and pH3.5-6.0, respectively, as well as in the case of the wild strain. The optimal temperature and thermal stability of avicelase II from the mutant strain were $40{\sim}50^{\circ}C\;and\;20{\sim}55^{\circ}C$, respectively. These results were same as those of the wild strain. By the using of Eadie-Hofastee plot, $K_m\;and\;V_{max}$ of avicelase II from the mutant and the wild strain were calculated to be 2.29mg/ml and $4.84{\mu}g$ reducing sugar as glucose per min equally, from the line fitted to the data by the least square method. Activity of avicelase II from the mutant strain was slightly activated by $Mg^{++}\;but\;inhibited\;by\;Cu^{++}, \;Mn^{++}\;and\;Zn^{++}$, as well as in the case of the wild strain. Therefore, it was concluded that the mutant didn't induce the formation of another avicelase isozyme, or the changes in the properties of avicelase, but induce the changes in the productively of the same avicelase II by the action of regulatory gane.

• The Korean Journal of Mycology
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• v.13 no.4
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• pp.203-212
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• 1985

Of 450 strains isolated from the soil microbes collected in various locations in Korea, a strain had a strong inhibitory activity against bacterial ${\alpha}-amylase$ and was named strain DMC-72 of the genus Streptomyces. The amylase inhibitory metabolite produced by this strain was purified by means of acetone precipitation, adsorption on Amberlite IRC-50 and SP-Sephadex C-25. The inhibitor was found to be a derivative of oligosaccharides by spectral and chemical data. The inhibitor was stable at the pH range of $1{\sim}13$ and at $100^{\circ}C$ for half an hour, also inhibited other amylases such as salivary ${\alpha}-amylase$, pancreatic ${\alpha}-amylase$, fungal ${\alpha}-amylase$ and glucoamylase. However, it showed no inhibitory activity against ${\alpha}-glucosidase$, ${\beta}-glucosidase$, dextranase, and ${\beta}-amylase$. The kinetic studies of the inhibitor showed that its inhibitory effects on starch hydrolysis by ${\alpha}-amylase$ were noncompetitive.

• Microbiology and Biotechnology Letters
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• v.40 no.4
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• pp.319-324
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• 2012

Production of liquid starters using wheat bran as a medium for Rhizopus oryzae N174 and the changes in their characteristics noted during storage were investigated in this study. The optimal culture conditions of the liquid starters were determined to be 5~15% (w/v) wheat bran and 48~72 hrs of incubation. The effects of liquid starters with different storage periods and temperatures (-18, 4, 10 and $25^{\circ}C$) on the quality of wheat nuruk were evaluated. According to the results of the pH, acidity, reducing sugar and enzyme activities, it was found that liquid starter using wheat bran preserved for one day, at any temperature, is the best method of storage for seed cultures for R. oryzae N174.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.5
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• pp.620-628
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• 2013

In this study, the condition for preventing abnormal fermentation was set by heating the nuruk extract, such that glycosyl enzymes maintain its activity and unnecessary microbes are removed. The total colony of microbes in the heated nuruk extract was highest in number at $25^{\circ}C$ and began to reduce at 50, $60^{\circ}C$ and sharply reduced over $70^{\circ}C$. Saccharogenic power (SP), glucoamylase and acidic protease activities were highest at $50^{\circ}C$, 10, 20, 30min and ${\alpha}$-amylase activity was lower at $50^{\circ}C$ than at $25^{\circ}C$. In the pHs of the nuruk extract, as the heat temperature became higher and treatment time was longer, the pHs were reduced significantly. The total acidities of heat treatments at 50, $60^{\circ}C$ were lower by 0.2% than at $25^{\circ}C$, where as the 70, $80^{\circ}C$ treatments showed a sharp rise from the early stage of fermentation. Soluble solids showed the same aspects with the glycosyl enzymes cases. In reducing sugar, 25, $50^{\circ}C$ treatments were sharply increased from the first day of fermentation while $60^{\circ}C$ treatments began to rise from second day 70, $80^{\circ}C$ were slightly increased after the fourth day. The normally alcohol fermented treatments were 25, 50 and $60^{\circ}C$ 30min. The $70^{\circ}C$ treatments almost did not alcohol fermentation. In the preference tests, taste and total acceptability were high at 25, $50^{\circ}C$ treatments. These results suggest that makgeolli using heat treated nuruk extract also has good taste as well as did not.

• KSBB Journal
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• v.10 no.3
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• pp.304-316
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• 1995

For fuel alcohol production, enzymatic liquefaction and saccharification of tapioca starch by ${\alpha}$-amylase and glucoamylase were studied. The thermophilic ${\alpha}$-amylase Termamyl produced from Bacillus licheniformis gave a better liquefaction than the relalively low temperature enzyme BAN from B. subtilis. Oplimal temperature and pH with Termamyl were $90∼95^{\circ}C$ and 5.8, respectively. Minimal amount of Termamyl 240uc for a satisfactory liquefaction for a two-hour reaction was about 0.0125% (v/w) with respect to the mass of tapioca used. For saccharification experiments two enzymes, Novo AMG and Do-I1 enzymes were compared. The enzymatic activity of each enzyme was a little different depending on the substrate used and the latter was found to have a significant amount of ${\alpha}$-amylase activity. With Novo AMG optimal temperature was about $58^{\circ}C$ The pH optimum was 4.3 with maltose, however, with tapioca, no difference was observed between pH 4.3 and 5.7 which is a natural, unadjusted pH of liquefied tapioca. For 85% of completion of saccharification, it was necessary to use 0.0625% (v/w) of Novo AMG 400L for tapioca and to run the reaction for more than 10 hr, Packed volume of solid particles in tapioca slurry remained at around 30% during liquefaction and saccharification. This indicates that the removal of the solid particle before fermentation is not economically feasible at all, even though the solid particles make it very difficult to operate the bioreactor in a continuous mode with cell-recycle.

• Korean Journal of Food Science and Technology
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• v.25 no.1
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• pp.1-8
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• 1993

Extruded defatted soy flour (DSF) with twin screw extruder was compared with steam treated DSF for soy sauce fermentation. Independent variables of response surface methodology (RSM) for extrusion were barrel temperature $(145{\sim}165^{\circ}C)$, feed moisture content $(25{\sim}35%)$, and feed rate $(20{\sim}30\;kg/hr)$. Extrusion conditions for production of the extrudates having highest water absorption capacity, lowest bulk density and highest expansion ratio were obtained by regression analysis of each dependent variable. Electron photomicrographs revealed significant increase of porosity inside the koji made from extruded DSF. Therefore, growth of fungi inside the koji made from extrudates of DSF was accelerated to achieve higher activities of protease, ${\alpha}-amylase$, and glucoamylase compared to the koji made from steamed DSF. Although amino acid composition of soy sauces prepared from two different DSF did not show any significant difference, the content of free amino acids in soluble nitrogen compounds was higher $(13%{\pm}2)$ in soy sauce made from extruded SDF. During the whole period of fermentation color of soy sauce made from extrudates of DSF was darker. Sensory evaluation did not reveal any serious off-odor and off-taste in the soy sauce fermented from extruded DSF.

• Korean Journal of Agricultural Science
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• v.11 no.1
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• pp.8-24
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• 1984

In this study, investigated the effects of four strains belonging to Aspergillus oryzae on the quality of Kochujang. In the Koji and Kochujang making, investigated the difference of enzyme production of each strain, the change of each component and color during the aging, and tested the sensory taste. The results obtained were as follows; 1. Protease activity (acid, neutral) in wheat flour Koji was high in the case of Aspergillus $oryzae-S_1$ and Aspergillus oryzae - M of short stalked type. The strain Aspergillus $oryzae-S_1$ showed maximum activity after two days of Koji making, while the strain Aspergillus oryzae - M showed low activity till two days, but showed maximum activity after three days-four days of Koji making. 2. In $\alpha$-amylase activity, strain Aspergillus $oryzae-S_1$, Aspergillus $oryzae-S_2$ and Aspergillus oryzae - M showed high activity after two days of Koji making. Aspergillus oryzae-NB strain showed slower ${\alpha}$ - amylase activity than that strains. 3. In glucoamylase activity, all strain tested showed high activity after three days of Koji making, but st rain Aspergillus oryzae - NB showed slower activity than ot - hers. 4. In protease activity (acid, neutral) during the aging of Kochujang, strain Aspergillus $oryzae-S_1$ and Aspergillus oryzae - M of short stalked type showed higher activity than that of long stalked type. 5. Amino type nitrogen contents during the aging of Kochujang was very higher in the case of strains Aspergillus $oryzae-S_1$ and Aspergillus oryzae - M of short stalked type than other strains, and each contents was 315mg% and 337mg% after aged for ninty days. 6. The results that analysed free sugar of Kochujang aged for ninty days with HPLC were; glucose 5.84~7.13%, fructose 4.13~5.00%, rhamnose 0.91~1.04%, maltose 0.72~0.92% and presence of xylose was recognized. 7. The results that analysed alcohols of Kochujang aged for ninty days with gas chromatography were; ethanol 1.51~1.78%, n-propyl alcohol 1.13~1.20mg%, iso-amyl alcohol 3.5~4.4mg%. 8. In the sensory test of Kochujang aged for sixty days and for ninty days, the case of strains Aspergillus oryzae-M and Aspergillus $oryzae-S_1$ of short stalked type showed good taste, while the case of strains Aspergillus $oryzae-S_2$ and Aspergillus oryzae-NB of long stalked type showed good flavor and color.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.1
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• pp.52-59
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• 2005

The study was targeted to saccharify foodwastes with the cellulolytic and amylolytic enzymes obtained from culture supernatant of Trichoderma harzianum FJ1 and analyze the kinetics of the saccharification in order to enlarge the utilization in industrial application. T. harzianum FJ1 highly produced various cellulolytic (filter paperase 0.9, carboxymethyl cellulase 22.0, ${\beta}$-glucosidase 1.2, Avicelase 0.4, xylanase 30.8, as U/mL-supernatant) and amylolytic (${alpha}$-amylase 5.6, ${\beta}$-amylase 3.1, glucoamylase 2.6, as U/mL-supernatant) enzymes. The $23{\sim}98\;g/L$ of reducing sugars were obtained under various experimental conditions by changing FPase to between $0.2{\sim}0.6\;U/mL$ and foodwastes between $5{\sim}20\%$ (w/v), with fixed conditions at $50^{\circ}C$, pH 5.0, and 100 rpm for 24 h. As the enzymatic hydrolysis of foodwastes were performed in a heterogeneous solid-liquid reaction system, it was significantly influenced by enzyme and substrate concentrations used, where the pH and temperature were fixed at their experimental optima of 5.0 and $50^{\circ}C$, respectively. An empirical model was employed to simplify the kinetics of the saccharification reaction. The reducing sugars concentration (X, g/L) in the saccharification reaction was expressed by a power curve ($X=K{\cdot}t^n$) for the reaction time (t), where the coefficient, K and n. were related to functions of the enzymes concentrations (E) and foodwastes concentrations (S), as follow: $K=10.894{\cdot}Ln(E{\cdot}S^2)-56.768,\;n=0.0608{\cdot}(E/S)^{-0.2130}$. The kinetic developed to analyze the effective saccharification of foodwastes composed of complex organic compounds could adequately explain the cases under various saccharification conditions. The kinetics results would be available for reducing sugars production processes, with the reducing sugars obtained at a lower cost can be used as carbon and energy sources in various fermentation industries.