• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.3
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• pp.425-432
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• 1998

The strain producing L-lactic acid from starch was isolated from kimchi. The isolated strain was identified as a homofermentative Streptococcus sp. through its morphological, cultural, biochemical characteristics, and named Streptococcus sp. JEJ-6. Lactic acids are of two types, one L-specific and the other D-specific form in a stereospecific form. Streptococcus sp. JEJ-6 produced selectively L-lactic acid from all of the tested carbon sources. The optimum conditions for the L-lactic acid production from the isolated microorganism were determined. For the maximum yield of L-lactic acid from Streptococcus sp. JEJ-6, the cell should be harvested at the early stationary phase, and the growth temperature, pH, and NaCl concentration should be 37$^{\circ}C$, pH 7.0 and 0.1%, respectively. 4% Soluble starch as substrate and organic nitrogen sources such as peptone and yeast extract should be used for the best yield. The optimum pH of the nicotinamide adenine dinucleotide(NAD)-dependent and NAD-independent lactate dehydrogenase(LDH) activities was pH 8.5 and pH 7.0, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.373-378
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• 2008

The pH & alkalinity adjustment method by lime and carbon dioxide($CO_2$) for corrosion control in water distribution system was investigated to determine the optimum operational condition in lime adding process in water treatment plant(WTP). The mixing time at dissolution tank and sedimentation time at saturator for maintaining optimal turbidity condition of lime supernatant were 60~75 minutes and 75~95 minutes, respectively. There was no difference according to $CO_2$ adding methods such as $CO_2$ saturated water or $CO_2$ gas. But, $CO_2$ saturated water could be convenience at WTP in terms of pH control and quantitative dosing. To minimize generation of calcium carbonate products, the short time interval between adding of lime and $CO_2$ is most important. The lime should be added below 32 mg/l for preventing pH rising and generation of calcium carbonate products at the heating condition.

• Korean Journal of Food Science and Technology
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• v.40 no.1
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• pp.70-75
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• 2008

Two extracellular amylase isozymes were purified and characterized from alkalophilic Pseudomonas sp. KFCC 10818 for the production of maltooligosaccharides. The molecular weights of the homogeneous proteins were 50 kDa and 75 kDa, respectively. The 50 and 75 kDa amylases showed optimum temperatures at 35 and $40^{\circ}C$, respectively. The optimum pH of the enzymes ranged from pH 6-8, and the enzymes were resistant to an alkaline condition of pH 12. Via the enzyme's actions, the final products from maltooligosaccharides or soluble starch were maltose and maltotriose. Calcium was a potent activator of the 50 kDa amylase. Finally, the N-terminal amino acid sequences of the 50 and 75 kDa amylases were QTVPKTTFV and DTVPGNAFQ, respectively.

• Food Engineering Progress
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• v.15 no.2
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• pp.143-147
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• 2011

For efficient extraction of protein from defatted rice bran, the 5 ranges of extraction pH (8, 9, 10, 11 and 12) and the 3 ranges of isoelectric precipitation pH (2, 4 and 6) were used. The protein content, browning reaction, the electrophoresis pattern and the recovery yield of soluble protein at each pH range were compared each other. The recovery yield of soluble protein increased in proportion to extraction pH, but at the same time, browning reaction became more conspicuous. The most amount of protein was recovered at the precipitation pH of 4. The SDS-PAGE patterns of the extracted proteins showed no significant correlations between pH and the protein content, but the highly alkaline condition was more advantageous to extract protein less than 35 kDa. In each pH range, the recovery yield of soluble protein averagely reached 32.5% on the basis of extraction. In result, it was found that combination of extraction pH 10 and precipitation pH 4, which resulted in 37.65% of recovery yield and low level of browning reaction, was the optimum condition for the extraction of protein from defatted rice bran.

• Food Science of Animal Resources
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• v.27 no.3
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• pp.329-336
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• 2007

This study was designed to find the optimum conditions for converting isoflavone glycoside to aglycone by ${\beta}-galactosidase$. Three different forms of the enzyme were tested and the optimum enzyme concentration, incubation temperature, pH, and incubation time were determined. Before treatment with enzyme, isoflavone contained 89.4% glycoside including daidzin, glycitin and genistin, and only 10.6% aglycone including daidzein, glycitein and genistein. Among the enzymes tested, the highest rate of isoflavone hydrolysis to aglycone, 35%, was observed when 3 unit/g Fungal Lactase (Amano Enzyme) was used. Higher incubation temperatures resulted in a higher rate of hydrolysis along with a greater loss of isoflavone mass. Therefore, body temperature $(37^{\circ}C)$ may be adequate for isoflavone conversion, with 44.9% hydrolysis and less than 10% loss of mass. As expected, a higher amount of aglycone was produced at pH 7 compared with other pH values. During 5hr of incubation, the conversion of glycoside to aglycone increased dramatically from 0 to 1hr, and plateaued thereafter. In addition, commercial soy-based milk was hydrolyzed more effectively with ${\beta}-galactosidase$ when incubated for 5hr. Based on the above results, the optimum conditions for isoflavone hydrolysis by ${\beta}-galactosidase$ were for 3 hr at $37^{\circ}C$, pH 7 with 3 unit/g Fungal Lactase (Amano Lactase), yielding an average total amount of aglycone ranging from 40 to 47%.

• Preventive Nutrition and Food Science
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• v.15 no.4
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• pp.316-321
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• 2010

Krill byproduct was hydrolyzed with Alcalase 2.4L to produce functional ingredients for high antioxidative activities against 1,1-dimethyl-2-picryl-hydrazyl (DPPH) radical and Fe. The objective of this study was to investigate the optimum condition for degree of hydrolysis and antioxidative activity of enzymatic hydrolysate produced with the commercial Alcalase using response surface methodology (RSM) with a central composite rotatable design (CCRD). The ranges of independent variables were pH 7.6~10.4 for initial pH and $50.9{\sim}79.1^{\circ}C$ for hydrolysis temperature and their dependent variables were degree of hydrolysis, Brix, amount of phenolic compounds, DPPH-scavenging activity and Fe-chelating activity. RSM with CCRD was well designed to investigate the optimum condition for functional ingredients with high antioxidative activities using Alcalase 2.4L because of their high $R^2$ values of the range of 0.93~0.99 except the $R^2$ value of 0.50 for the amount of total phenolic compounds. The optimum hydrolysis conditions were pH 9.5 and $62^{\circ}C$ for degree of hydrolysis (DH) and pH 9.1 and $64^{\circ}C$ for DPPH-scavenging activity by response surface methodology. The yield of DH and DPPH-scavenging activity were $14.1{\pm}0.5%$ and $10.5{\pm}0.2%$, respectively. It is advantageous to determine the optimum hydrolysis conditions of krill and its by-products for the creation of different kinds of food products, as well as to increase the usage of marine protein sources.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.2
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• pp.240-245
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• 1993

The optimum pH and temperature for the purified extracellular enzyme activity were 8.0 and 37$^{\circ}C$, respectively. NaCl was required for the activation of the enzyme and optimum concentration was 0.5M. This enzyme activity was inhibited by HgC $l_2$, CoC $l_2$ and ZnC $l_2$ and stimulated by CaC $l_2$. The activity of enzyme was increased by L-cysteine and 2-mercaptoethanol, but decreased by ο-phenanthroline, $\rho$-CMB, EDTA and iodoacetate. The $K_{m}$ and $V_{max}$ values of extracellular enzyme appeared as 0.717% and 15.39U/mg, respectively.y.

• Journal of Environmental Science International
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• v.18 no.11
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• pp.1235-1245
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• 2009

The purpose of this study is to investigate electro-generation of free Cl, $ClO_2$, $H_2O_2$ and $O_3$ and degradation of Rhodamine B in solution using Ru-Sn-Sb electrode. Electrolysis was performed in one-compartment reactor using a dimensionally stable anode(DSA) of Ru-Sn-Sb/Ti as the working electrode. The effect of applied current (0.5-3 A), electrolyte type (NaCl, KCl, HCl, $Na_2SO_4$ and $H_2SO_4$) and concentration (0.5-2.5 g/L), air flow rate (0-3 L/min) and solution pH (3-11) was evaluated. Experimental results showed that concentration of 4 oxidants was increased with increase of applied current, however optimum current for RhB degradation was 2 A. The generated oxidant concentration and RhB degradation of the of Cl type-electrolyte was higher than that of the sulfate type. The oxidant concentration was increased with increase of NaCl concentration and optimum NaCl dosage for RhB degradation was 1.75 g/L. Optimum air flow rate for the oxidants generation and RhB degradation was 2 L/min. $ClO_2$ and $H_2O_2$ generation was decreased with the increase of pH, whereas free Cl and $O_3$ was not affected by pH. RhB degradation was increase with the pH decrease.

• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.301-306
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• 2020

We investigated the individual biosorption removal of lead, copper, and nickel ions from aqueous solutions using Chara sp. algae powder in a batch mode. The impact of several parameters, such as initial concentration of the metal ions, contacting time, sorbent dose, and pH on the removal efficiency, was investigated. The maximum removal efficiency at optimum conditions was found to be 98% for Pb(II) at pH = 4, 90% for Cu(II) at pH = 5, and 80% for Ni(II) at pH = 5. The isotherm study was done under the optimum conditions for each metal by applying the experimental results onto the well-known Freundlich and Langmuir models. The results show that the Langmuir is better in describing the isotherm adsorption of Pb(II) and Ni(II), while the Freundlich is a better fit in the case of Cu(II). Similarly, a kinetic study was performed by using the pseudo-first and second-order equations. Our results show that the pseudo-second-order is better in representing the kinetic adsorption of the three metal ions.

• KSBB Journal
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• v.17 no.6
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• pp.509-514
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• 2002

Experiments were carried out to optimize the fermentation conditions for the production of erythritol by salt-tolerant mutant, Candida magnoliae M26. The optimum conditions of erythritol production showed a 1.0 vvm aeration and 500 rpm agitation at 28$\^{C}$ with an initial medium pH of 7.0. The pH control during the fermentation did not improve the erythritol yield and productivity. The maximum erythritol concentration of 143.3 g/L was obtained with 57% yield and 0.70 g/L-h productivity from 250 g/L of glucose and 5 g/L of yeast extract under an optimum fermentation conditions. The medium containing 0.5 M KCl or 0.5 M NaCl enhanced the production of erythritol and glycerol. However, glycerol production increased and erythrtiol production decreased by increasing the concentration of NaCl or KCl.