• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.172-177
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• 2017

A novel biosorbent, immobilized Saccharomyces cerevisiae in magnetic chitosan microspheres was prepared, characterized, and used for the removal of $Sr^{2+}$ from aqueous solution. The structure and morphology of immobilized S. cerevisiae before and after $Sr^{2+}$adsorption were observed using scanning electron microscopy with energy dispersive X-ray spectroscopy. The experimental results showed that the Langmuir and Freundlich isotherm models could be used to describe the $Sr^{2+}$ adsorption onto immobilized S. cerevisiae microspheres. The maximal adsorption capacity ($q_m$) was calculated to be 81.96 mg/g by the Langmuir model. Immobilized S. cerevisiae was an effective adsorbent for the $Sr^{2+}$ removal from aqueous solution.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10a
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• pp.43-44
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• 2003

The new method for preparing hybrid fibers from aqueous solution is described. The method is based on interfacial polyionic complexation between the counter-charged polymers. Polysaccharides, chitosan and gellan, and polypeptides, poly(L-lysine) and poly(L-glutamic acid) were utilized as the components of the fibers. The chitosan-gellan and poly(L-lysine)-gellan hybrid fibers exhibited a high level biodegradability.

• Textile Coloration and Finishing
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• v.10 no.1
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• pp.38-42
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• 1998

Both cellulose and chitin together were dissolved in DMAc/LiCl and these solutions were extruded into coagulant of $DMAc/H_2O$. Fibers thus obtained were treated in NaOH aqueous solution. Results showed that the fiber surface contains celluose and chitosan. This means that these fibers treated are composed of three components, ie, cellulose, chitin, and chitosan. These fiber showed secure antibacterial and mechanical properties.

• Food Science of Animal Resources
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• v.38 no.3
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• pp.636-652
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• 2018

The study aims to determine the optimum sterilization rate and water activity of Chinese traditional smoke-cured bacon product (Larou) in the preservation with natural coating solution. With the response surface methodology (RSM), we analyzed 3 factors of processing conditions (the concentration of lysozyme, concentration of sodium alginate, and concentration of chitosan) and 2 response factors (sterilization rate and water activity). Sterilization rate and water activity of Larou were largely affected by the concentration of lysozyme, concentration of sodium alginate, and concentration of chitosan. The final optimum concentrations of lysozyme, sodium alginate, and chitosan were 0.09, 1.40, and 1.60% and realized the high sterilization rate. Water activity of sliced Larou was significantly correlated with the sterilization rate. Low-field nuclear magnetic resonance analysis verified the optimum processing conditions. The coating resulted in 99.69% rate of reducing bacteria after 30-day storage. The data of the total number of colony, peroxidation value, moisture content, pH, and sensory evaluation provided the theoretical basis for extending the shelf life of Chinese traditional smoke-cured bacon product (Larou) with natural coating solution.

• KSBB Journal
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• v.17 no.6
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• pp.515-519
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• 2002

The changes in the levels of total soluble protein and some free amino acids were investigated in germinating brown rice. Nongerminated (N) brown rice was germinated for 72 hrs by applying following solutions: 1) distilled water (W), 2) 50 ppm chitosan in 5 mM lactic acid (CL), and 4) 50 ppm chitosan in 5 mM glutamic acid (CG). The level of total soluble protein was higher in the N extract than those of W, CL and CG. Alanine levels were enhanced and aspartic acid levels were decreased significantly in the germinated brown rice, highest increases of alanine were found in the CG germinated brown rice. The levels of serine, decreased during germination in solutions W and CL, were increased significantly by germination in CG solution. The levels of essential amino acids, such as Iysine, isoleucine and methionine were also increased significantly by germination in CG solution. Our results show that the germination of brown rice with CG solution can significantly increase the levels of alanine and some other essential amino acids and can restore the serine level.

• Clean Technology
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• v.7 no.4
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• pp.281-290
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• 2001

A microwave-assisted process to prepare chitosan from natural crabshells has been investigated. This study was primarily to examine the effectiveness of microwave as clean energy for chitosan preparation. Several human-edible organic acids were used as clean catalyst, possibly to improve the current HCl-based hydrolysis process of polymeric chitosan. The microwave was found to be effective substantially in reducing the reaction time. Nonetheless, no beneficial effect of microwave other than time, such as the chemical selectivity, was hardly observed. The organic acids were very effective in the hydrolysis reaction of polymeric chitosan. Their catalytic behavior was greatly improved especially when reactions were performed under pressure. In the case of autoclave reaction for 60 minutes at $120^{\circ}C$, viscous solution of polymeric chitosan (mol. wt. > 300,000) turned into thin solutions of water-like viscosity, which means chitosan molecules were decomposed to very small-sized oligomers.

• Journal of Environmental Health Sciences
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• v.29 no.3
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• pp.72-78
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• 2003

In the process of producing chitosan from crustacean shell, the use of excessive acid and alkli is causing the problems of environmental pollution and of production cost. In this study, one way to solve these problems is to cultivate fungi, then, to extract chitosan from the cell wall. By means of flask incubation and batch cultivation, the optimum cultivation conditions for mass production of continuous cultivation was found. Four strains used for the production of fungal chitosan were Gongronella butleri IF08080, Absidia coerulea IF05301, Rhizopus delemar IF04775, Mucor tuberculisporus IF09256. In flask incubation to select strain of producing much chitosan by means of experiment of the effect of initial pH, Absidia coerulea IFO 5301 had highest yield in FCs, 258.1 $\pm$ 47.3 mg/200 $m\ell$l at pH 6.5. In flask incubation under the optimum cultivation condition, temperature 27$^{\circ}C$, culture time 6days, glucose 2%, peptone 1%, (NH$_4$)$_2$ SO$_4$ 0.5%, $K_2$HPO$_4$ 0.1 %, Nacl 0.1 %, MgSO$_4$ㆍ7$H_2O$ 0.05%, CaCl$_2$ㆍ2$H_2O$ 0.01 %, the yield of DCW brought the highest yields. In batch bioreactor, the optimum cultivation condition was that cell suspended solution was 70 $m\ell$, aeration rate 0.5 l/min, agitation rate 800 rpm, culture time 36 hr. In continuous bioreactor, the optimum substrate flow rate was 4 ι/day.

• Polymer(Korea)
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• v.29 no.4
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• pp.408-412
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• 2005

Structure and characteristic of the films blended chitosan matrix with silk fibroin, extracted from Bombyx mori, were studied by X-ray diffraction, differential scanning calorimetry, FT-IR spectra analysis, SEM photographs, contact angle measurement and water absorbency in order to use as biomaterials. The blend films of $0\~30 wt\%$ fibroin content were prepared in acetic solution with $Li^+$ ion. It was found that the crystallinity of chitosan/fibroin blend films was decreased by the presence of intermolecular interactions such as hydrogen bonding between animo groups of chitosan and carbonyl groups of fibroin. As the proportion of fibroin in the blend increased, anhydrous crystalline phase of chitosan disappeared, and hydrated crystalline phase decreased, and $\beta$-structure crystalline phase of fibroin was formed. Therefore the blend films were crystallized into two different crystalline region of chitosan and fibroin. Surface hydrophilicity and water absorbency increased with blending fibroin. Above 20 $wt\%$ fibroin content, hydrogel film was formed. The surface and section of the film showed uniform microstructure on SEM photographs.

• Journal of Microbiology and Biotechnology
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• v.22 no.6
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• pp.818-825
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• 2012

Keratinases are exciting keratin-degrading enzymes; however, there have been relatively few studies on their immobilization. A keratinolytic protease from Chryseobacterium sp. kr6 was purified and its partial sequence determined using mass spectrometry. No significant homology to other microbial peptides in the NCBI database was observed. Certain parameters for immobilization of the purified keratinase on chitosan beads were investigated. The production of the chitosan beads was optimized using factorial design and surface response techniques. The optimum chitosan bead production for protease immobilization was a 20 g/l chitosan solution in acetic acid [1.5% (v/v)], glutaraldehyde ranging from 34 g to 56 g/l, and an activation time between 6 and 10 h. Under these conditions, above 80% of the enzyme was immobilized on the support. The behavior of the keratinase loading on the chitosan beads surface was well described using the Langmuir model. The maximum capacity of the support ($q_m$) and dissociation constant ($K_d$) were estimated as 58.8 U/g and 0.245 U/ml, respectively. The thermal stability of the immobilized enzyme was also improved around 2-fold, when compared with that of the free enzyme, after 30 min at $65^{\circ}C$. In addition, the activity of the immobilized enzyme remained at 63.4% after it was reused five times. Thus, the immobilized enzyme exhibited an improved thermal stability and remained active after several uses.

• KSBB Journal
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• v.15 no.6
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• pp.615-620
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• 2000

To obtain quality germinated brown rices containing high levels of ${\gamma}$-aminobutyric acid (GABA), chitosan was applied during the brown rice germination. The GABA contents in germinated brown rices (1,035 nmole/g fresh weight) and brown rices germinated by water (771 nmole/g fresh weight) or by lactiv acid (728 nmole/g fresh weight). In addition to the enhancement of GABA, germination in the chitosan solution increased alanine concentration and decreased glutamic acid, aspartic acid and serine concentrations in the brown rices. The activity of glutamate decarboxylase was also enhanced by the chitosan treatment. Furthermore, germination by chitosan reduced fungal contamination markdely, compared with germination by water or germination by lactic acid. These results suggest that quality germinated brown rices containing high levels of GABA can be obtained by chitosan application.