• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.5
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• pp.779-785
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• 1996

The qualities of bread and change of phytic acid during breadmaking with whole wheat flour were investigated. The ratios of ash contents in wheat flour and whole wheat flour were 0.41% and 1.57%, respectively. The ratios of fiber contents in wheat flour and whole wheat flour were 0.14% and 1.83%, respectively. In amino acid analysis, glutamic acid was determined to be 32~36g/100g protein, which was the highest. Lysine, glycine, arginine and aspartic acid were higher in whole wheat flour than those of wheat flour. Proline, glutamic acid, and phenylalanine were higher in wheat flour than those of whole wheat flour. The ratio of phytic acid content in wheat flour and whole wheat flour was 0.312% and 0.734%, respectively. The content of phytic acid during beadmaking was decreased approximately 65% after proofing, while this was almost constant in the process of oven baking. The content of phytic acid in bread with 3% yeast had less hydrolysis than that in bread with 5% yeast during breadmaking. The phytic acid content in the 0.1% yeast food was decreased more than the 0, 0.3, and 0.5% yeast food groups. As the amount of whole wheat flour increased, the volume of bread was decreased, and color became dark. The sensory evaluation was showed the quality of bread to be the highest when the amounts of coarse whole wheat flour and fine whole wheat flour was 20% and 30%, respectively. Though the amount of coarse whole wheat flour and fine whole wheat flour were increased up to 30% and 50%, respectively, external characteristics of bread was remained in normal.

• Resources Recycling
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• v.16 no.5
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• pp.8-12
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• 2007

Anhydrous magnesium chloride, dehydration product from magnesium chloride hydrate is a general raw material to prepare electrolytic magnesium. However, the dehydration is not trivial and can be accompanied by hydrolysis leading to the production of undesirable hydroxy chloride compounds of magnesium. Therefore, dehydration process is actually the most complicated and hardest in the electrolysis methods for the production of magnesium. In this work, the influence of dehydrating temperature has been studied at the temperature range from $200^{\circ}C$ to $600^{\circ}C$ in air and HCl gas atmosphere individually to compare the results. With increasing of dehydration temperature MgOHCl and MgO were obtained in air. On the other hand, when the temperature was increased above $300^{\circ}C$ anhydrous magnesium chlorides were prepared in HCl gas atmosphere. Anhydrous magnesium chloride was formed at near $300^{\circ}C$ and completely crystallized at about $500^{\circ}C$. All of the HCl used as atmosphere gas in the dehydration was recovered as hydrochloric acid solution at a water vessel up to 41% by weight at $20^{\circ}C$.

• Journal of Life Science
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• v.23 no.12
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• pp.1486-1494
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• 2013

A high protease-producing strain was isolated and identified from the digestive tract of octopus vulgaris by detecting a hydrolysis circle of protease and its activity. The strain was identified by morphology observation, biochemical experiments, and 16S rRNA sequence analysis. The protease obtained from the strain was purified by a three-step process involving ammonium sulfate precipitation, carboxy methyl-cellulose (CM-52) cation-exchange chromatography, and DEAE-Sephadex A50 anion-exchange chromatography. The properties of protease were characterized as well. The strain Bacillus sp. QDV-3, which produced the highest activity of protease, was isolated. On the basis of the phenotypic and biochemical characterization and 16S rRNA gene-sequencing studies, the isolate was identified as follows: domain: Bacteria; phylum: Firmicutes; class: Bacilli; order: Bacillales; family: Bacillaceae; and genus: Bacillus. The isolate was shown to have a 99.2% similarity with Bacillus flexus. A high active protease designated as QDV-E, with a molecular weight of 61.6 kDa, was obtained. The enzyme was found to be active in the pH range of 9.0-9.5 and its optimum temperature was $40^{\circ}C$. The protease activity retained more than 96% at the temperature of $50^{\circ}C$ for 60 min. Phenylmethylsulfonyl fluoride (PMSF) inhibited the enzyme activity, thus confirming that this protease isolated from Bacillus sp. QDV-3 is an alkaline serine protease. Metal ions, $Mn^{2+}$ and $Mg^{2+}$, were determined to enhance the protease activity, whereas $Ba^{2+}$, $Zn^{2+}$, and $Cu^{2+}$ were found to inactivate the enzyme.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1073-1081
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• 2000

The photo-oxidation of an aqueous humic acid solution using $TiO_2$ sols. which is transparent in visible range, was studied. The $TiO_2$ sols were prepared by a process wherein hydrogen peroxide was added to a gel of $TiO(OH)_2$ originated from hydrolysis of $TiCl_4$, and the resulting titanium peroxo solution(TPS) was heated. The concentration of $TiO_2$ used for photo-oxidation was about 100ppm, determined by comparing the photoluminescence(PL) intensity measured as a function of $TiO_2$ concentration. $TiO_2$ sols aged at $100^{\circ}C$ for more than 12h were found to exhibit a maximum rate in photocatalytic decomposition of humic acid. and the efficiency was better than that of Degussa P25. In addition, the resulting aqueous humic acid after photocatalytic decomposition with sols had an excellent transmittance of visible light, while that treated with Degussa P25 was still turbid. caused by $TiO_2$ particles.

• Korean Journal of Materials Research
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• v.11 no.2
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• pp.94-103
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• 2001

SiO$_2$ and PDMS/SiO$_2$ xerogels which are derived PDMS into TEOS have been synthesized by sol-gel process and controlled pore size and distribution through 2 step acid/base catalyzed processes using HCI and NH$_4$OH as a catalyst. In HCl catalyzed SiO$_2$ and PDMS/SiO$_2$ xerogels, pH and gellation time of xerogel were 2.3~2.5 and 12~13 days, respectively, and the shape of xerogel was identified to pellet type and column type. Under acidic condition of final reaction solution, the hydrolysis rate is accelerating, resulting in long gel times. The shape of xerogel is pellet type. In contrast, under less acidic condition, the condensation rate is accelerating, resulting in shorter gel times and the shape of xerogel is column type. The surface area and average Pore size were changed 400$\rightarrow$600($\m^2$/g) and 15$\rightarrow$28$\AA$, respectively, depending to the increase of the mole ratio of HCl/NH$_4$OH, and represented uniform pore size distribution. It is that all the alkoxide groups are hydrolyzed by HCl after the first step and the condensation rate is enhanced by NH$_4$OH. The regular backbone structures of silica are formed at low temperature and the uniform pores are produced by heat treatment.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.749-757
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• 2019

Methyltrimethoxysilane (MTMS) and trimethylethoxysilane (TMES) as starting materials were dissolved in various types of solvents, and hydrolysis with water and polycondensation reaction were carried out using various types of catalysts to prepare non-fluorinated water-repellent coating solutions. The coating solutions were spin-coated on cold-rolled steel sheets, and thermally cured to prepare water-repellent coating films. The effect of types of catalysts and solvents on the water repellency of the resulting coating films was investigated during this process. When hydrochloric acid and nitric acid, which are strong acids, were used as catalysts, the solutions showed a white opaque state due to the aggregation of siloxane polymers. On the other hand, when acetic acid, phosphoric acid, and oxalic acid, which are weak acids, were used, they were in a stable and transparent state without precipitation. As a result, the contact angles of the coated films, prepared from hydrochloric acid and nitric acid, were $58^{\circ}$ and $92^{\circ}$, respectively, showing low water repellency. On the other hand, when acetic acid, phosphoric acid, and oxalic acid were used, the contact angles of the coated films were $101^{\circ}$, $103^{\circ}$ and $116^{\circ}$, respectively, showing high water repellency. In addition, when isopropanol and ethanol were used as solvents, phase separation occurred in the solutions due to the aggregation of siloxane polymers. On the other hand, when methanol, ethyl acetate, and methyl ethyl ketone were used as solvents, the solutions were transparent and showed a stable state without sedimentation.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.414-422
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• 2022

The objective of this work was to investigate the feasibility of acid-catalyzed hydrothermal fractionation for maximum solubilization of the hemicellulosic portion of two typical agricultural residues. The fractionation conditions converted into combined reaction severity (CS) in the range of 1.2-2.9 was used to establish a simple reaction criteria at glance. The hemicellulosic sugar yield of 56.6% was shown when rice straw was fractionated at the conditions at the conditions; 160 ℃ of temperature 0.75% (w/v) of H₂SO₄, 20 min of reaction time, 1:15 solid/liquid ratio. The hemicellulosic sugar yield of 83.0%, however, was achieved when barley straw was fractionated at the conditions at the conditions; 150 ℃ of temperature 0.75% (w/v) of H₂SO₄, and 15 min of reaction time, 1:10 solid/liquid ratio. For barley straw, acid-catalyzed hydrothermal fractionation could be effectively performed. After the fractionation process, the remaining fractionated solids were 48.5% and 57.5% from raw rice and barley straws, respectively. The XMG contents in the solid residues decreased from 17.3% and 17.6% to 6.0% and 2.6%, which corresponded to 16.7% and 8.5% on the basis of the raw straws, respectively. In another way, only 5.6% of cellulose and 8.5% of XMG were lost due to excessive decomposition during the acid-catalyzed hydrothermal fractionation of barley straw, compared to cellulose and XMG losses of 6.4% and 26.6% in rice straw. Hemicellulosic sugars from the rice straw were considered more over-decomposed due to the somewhat higher reaction severity at the acid-catalyzed hydrothermal fractionation.

• Journal of the Korean Society of Food Culture
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• v.1 no.3
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• pp.267-278
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• 1986

The evolution of Korean fish fermentation technology was reviewed from the old literatures and the on-going processes were surveyed. The principles involved in the traditional fermentation methods were explained by the recent scientific findings. The fish fermentation technology be classified into two groups; jeot-kal process, where. salt is the only material added to the fish for fermentation, and sik-hae process, where cooked cereals, garlic and red pepper powder are added to the salted fish. A total of 46 kinds of jeot-kal was identified in a survey, depending on the raw materials used. The characteristic feature of Korean jeot-kal process is to produce fermented products which still has original shape after 2-3 months of fermentation to be used for side-dishes of rice meal, as well as fish sauce by keeping these products for longer time (over 6 months) for severe ansymematic hydrolysis to be used for the subingredient of Kimchi (Korean fermented vegetable food). The taste of jeot-kal is formed by the protein hydrolymates due to the action of salt-tolerant Pediococcus, Bacillus, Halobacterlum etc. When the taste of jeot-kal deteriorates, yeasts appear to dominate. In ski-hae fermentation, the safety of preserved fish is kept by the rapid decrease in pH resulting from the acid fermentation of added cereals. The roles of cid forming bacteria and proteloytic bacteria are important. The fermentation is completed in 2 weeks and the excess production of acid during prolonged storage limits the taste acceptability. The fish fermentation technology in Korea stands at important position in Korean food science and technology. since the processes of jeot-kal and soysauce have same root in the principle of microbial proteolysis and the processes of sik-hae and Kimchi in the microbial acid production principles.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.3
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• pp.15-25
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• 2023

In this study, silicon sludge from semiconductor dicing process is recycled to fabricate silica nanoparticles, which are applied as dispersing materials for electro-responsive (ER) smart fluid. In specific, metal impurities are removed from silicon sludge by acid washing to obtain the high-purity silicon powder. And then, silica nanoparticles are synthesized by facile hydrothermal method employing the silicon powder as reactant material. To control the size of silica nanoparticles, the reaction time of hydrothermal method is varied as 8, 15, 20, and 30 hours are applied to control the size of silica nanoparticles. Sizes of silica nanoparticles are increased proportionally to the reaction time owing to the increased numbers of hydrolysis and condensation reactions. As-synthesized silica nanoparticles are prepared as electro-responsive smart fluids by dispersing into silicon oil. Silica nanoparticles synthesized by 30 hours of hydrothermal reaction (SiO₂-H30) exhibit the highest shear stress of 21.4 Pa under an applied electric field strength of 3.0kV mm^-1. Such enhancement in ER performance of SiO₂-H30 among various silica nanoparticles are attribute to the reinforcing effect originated from the mixed particle size, which allowing the formation of rigid chain-like structures. Accordingly, this study successfully propose a recycling method of silicon sludge to synthesize silica nanoparticles and their derived ER fluids, which may suggest new possibility to ESG management emphasizing the eco-friendliness.

• Journal of Sericultural and Entomological Science
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• v.16 no.1
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• pp.21-48
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• 1974

The studies were carried out to disclose the physical and chemical properties of sericin fraction obtained from silk cocoon shells and its characteristics of swelling and solubility. The following results were obtained. 1. The physical and chemical properties of sericin fraction. 1) In contrast to the easy water soluble sericin, the hard soluble sericin contains fewer amino acids include of polar side radical while the hard soluble amino acid sach as alanine and leucine were detected. 2) The easy soluble amino acids were found mainly on the outer part of the fibroin, but the hard soluble amino acids were located in the near parts to the fibroin. 3) The swelling and solubility of the sericin could be hardly assayed by the analysis of the amino acid composition, and could be considered to tee closely related to the compound of the sericin crystal and secondary structure. 4) The X-ray patterns of the cocoon filament were ring shape, but they disappeared by the degumming treatment. 5) The sericin of tussah silkworm (A. pernyi), showed stronger circular patterns in the meridian than the regular silkworm (Bombyx mori). 6) There was no pattern difference between Fraction A and B. 7) X-ray diffraction patterns of the Sericin 1, ll and 111 were similar except interference of 8.85A (side chain spacing). 8) The amino acids above 150 in molecular weight such as Cys. Tyr. Phe. His. and Arg. were not found quantitatively by the 60 minutes-hydrolysis (6N-HCI). 9) The X-ray Pattern of 4.6A had a tendency to disappear with hot-water, ether, and alcohol treatment. 10) The partial hydrolysis of sericin showed a cirucular interference (2A) on the meridian. 11) The sericin pellet after hydrolysis was considered to be peptides composed with specific amino acids. 12) The decomposing temperature of Sericin 111 was higher than that of Sericin I and II. 13) Thermogram of the inner portioned sericin of the cocoon shell had double endothermic peaks at 165$^{\circ}C$, and 245$^{\circ}C$, and its decomposing temperature was higher than that of other portioned sericin. 14) The infrared spectroscopic properties among sericin I, II, III and sericin extracted from each layer portion of the cocoon shell were similar. II. The characteristics of seriein swelling and solubility related with silk processing. 1) Fifteen minutes was required to dehydrate the free moisture of cocoon shells with centrifugal force controlled at 13${\times}$10$^4$ dyne/g at 3,000 R.P.M. B) It took 30 minutes for the sericin to show positive reaction with the Folin-Ciocaltue reagent at room temperature. 3) The measurable wave length of the visible radiation was 500-750m${\mu}$, and the highest absorbance was observed at the wave length of 650m${\mu}$. 4) The colorimetric analysis should be conducted at 650mu for low concentration (10$\mu\textrm{g}$/$m\ell$), and at 500m${\mu}$ for the higher concentration to obtain an exact analysis. 5) The absorbing curves of sericin and egg albumin at different wave lengths were similar, but the absorbance of the former was slightly higher than that of the latter. 6) The quantity of the sericin measured by the colorimetric analysis, turned out to be less than by the Kjeldahl method. 7) Both temperature and duration in the cocoon cooking process has much effect on the swelling and solubility of the cocoon shells, but the temperature was more influential than the duration of the treatment. 8) The factorial relation between the temperature and the duration of treatment of the cocoon cooking to check for siricin swelling and solubility showed that the treatment duration should be gradually increased to reach optimum swelling and solubility of sericin with low temperature(70$^{\circ}C$) . High temperature, however, showed more sharp increase. 9) The more increased temperature in the drying of fresh cocoons, the less the sericin swelling and solubility were obtained. 10) In a specific cooking duration, the heavier the cocoon shell is, the less the swelling and solubility were obtained. 11) It was considered that there are differences in swelling or solubility between the filaments of each cocoon layer. 12) Sericin swelling or solubility in the cocoon filament was decreased by the wax extraction.. 13) The ionic surface active agent accelerated the swelling and solubility of the sericin at the range of pH 6-7. 14) In the same conditions as above, the cation agent was absorbed into the sericin. 15) In case of the increase of Ca ang Mg in the reeling water, its pH value drifted toward the acidity. 16) A buffering action was observed between the sericin and the water hardness constituents in the reeling water. 17) The effect of calcium on the swelling and solubility of the sericin was more moderate than that of magnecium. 18) The solute of the water hardness constituents increased the electric conductivity in the reeling water.