• Research in Plant Disease
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• v.15 no.3
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• pp.248-253
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• 2009

Chitosan has an antifungal activity and is widely used for control of various plant disease and plants growth in the field in Korea. Disease control efficacy of two preparations (SH-1, SH-2) of mixtures of high and low (chitooligosaccharide) molecular weight chitosan compounds against tomato leaf mold caused by Fulvia fulva was investigated under plastic greenhouse conditions. Both SH-1 and SH-2 formulations displayed potent disease control activity in two experiments. The protective activity of both preparations was comparable to synthetic thiophanate-M. The persistence activity of the formulations was sustained until 21 days after application. Effective concentration of the chtosan compounds for disease control was 1,200 mg a.i./L. In pot tests, chitosan preparations, at a concentration of 600 mg a.i./L, promoted plants growth. These results indicate that the chitosan preparations have a potential as an eco-friendly natural fungicide for the control of tomato leaf mold and plant growth regulator.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.457-465
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• 2008

Development of various medical systems was accomplished through the progress of biotechnological method for therapy of human diseases. Furthermore, drug delivery systems have been investigated to carry the bioactive materials such as drug or gene in the body effectively. The most important thing in this system is to develop biomedical polymers having biocompatibility, biodegradability, and non-toxicity. Chitosan, a natural polymer, has been importantly considered as biomedical materials due to its good biocompatibility and various bio-active characteristics. Since the property of chitosan is differently explained according to the crystalline structures of chitin, the study for structural analysis of chitin has to proceed to apply as a biomaterial. From this point of view, this article introduced the analysis of crystalline structural of chitin, general property of chitosan and potential characteristics of low molecular weight water-soluble chitosan (LMWSC) as a biomaterials. Furthermore, chemical modification of LMWSC using various functional groups was also performed to enhance its bioavailability and emphasize their potential as drug delivery carriers (DDS).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.2
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• pp.70-78
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• 1989

This experiment was carried out to develop the preparation method of chitosan which has strong antimicrobial activity, and also tried to investigate as a natural food preservative with this chitosan. The antimicrobial activity of chitosan was the strongest when deacetylation of chitin was conducted at $146^{\circ}C$ for 8 hours with $50\%$ sodium hydroxide. The growth of Escherichia coil was completely inhibited by adding this low molecular weight chitosan (M. W, 35,000) at the level of concentration of 75ppm to the medium. The antimicrobial activity was strong enough against such Gram positive bacteria as Staphylococcus sp. and Bacillus sp.. The growth of these strains was inhibited by the concentration of 50ppm but it was varied in its kinds against Gram negative bacteria. The concentration of chitosan re-quired for growth inhibition of microorganisms was 100ppm against Pseudomonas sp. and Vibrio sp., 2,000ppm against Salmonella sp.. The growth of Saccharomyces sp. was inhibited by the concentration of 100ppm, but Hansenula sp., Aspergillus sp., Penicillium sp. and Mu-cor sp. did not inhibited by even more than the concentration of 5,000ppm. The shelf life of Mulkimchi (pickle type Kimchi), containing $0.2\%$ chitosan was 10 days longer than control stored at $5^{\circ}C$.

• Food Science of Animal Resources
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• v.25 no.3
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• pp.285-294
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• 2005

The objective of this study was to evaluate the physico-chemical properties and flavor compounds of sausages with various levels and molecular weight (MWs) of chitosans, during storage at $4^{\circ}C$. Various MWs (Low: 1.5 kDa; Medium: $30{\sim}50$ kDa; High: 200 kDa) and two levels (0.3 and $0.6\%$) of chiosans were dissolved and measured the viscosity at $4^{\circ}C$, pH values were not affected (p>0.05) by either MWs or levels of chitosans. The addition or high MWs or chitosan into the pork salt soluble protein (SSP) increased the viscosity, whereas no differences were observed in low and medium MWs of chitosan. Textural profile analysis (TPA) was affected by the addition of medium or high MWs of chitosan. As a result, the addition of medium of chitosan increased the hardness, gumminess, chewiness, cohesiveness and springiness values, whereas increased level of chitosan didn't affect TPA values, except few cases. Approximately twenty-nine flavor compounds were identified in the low-fat and regular-fat sausages, however the addition of chitosans didn't impair the flavor composition of the sausages, These results indicated that the addition of chitosans didn't affect the flavor profiles, but affected the textural properties in the sausages, especially MWs higher than 30 kDa.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.7
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• pp.857-867
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• 2017

This study was performed to encapsulate low molecular weight marine collagen and ${\gamma}$-aminobutyric acid (GABA)-producing lactic acid bacteria to inhibit degradation and improve survival rate during exposure to adverse conditions of the gastro-intestinal tract. Calcium-alginate method was used for the manufacture of a double-layered coated capsule. The inner core material was composed of collagen and lactic acid bacteria, and the coating materials were alginate and chitosan. The sizes and shapes of the double-coated capsule were affected mainly by centrifuge speed and pH. Manufactured capsules were observed with a scanning electron microscope and by confocal laser scanning microscopy to confirm the micromorphological changes of capsules and bacterial cells. As a result, double-layered coated capsules were not degraded at pH 1.2, whereas degradation occurred at pH 7.4. In addition, GABA and collagen were maintained in stable state at pH 1.2. Therefore, double-layered coated capsules developed in this study would not be degraded in the stomach and could be stably delivered to the small intestine to benefit intestinal and dermatic health.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1312-1321
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• 2011

Enzyme extracts of cellulase [filter paper cellulase (FPase) and carboxymethyl cellulase (CMCase)], chitinase, and chitosanase produced by Aspergillus niger NRRL-567 were evaluated. The interactive effects of initial moisture and different inducers for FP cellulase and CMCase production were optimized using response surface methodology. Higher enzyme activities [FPase $79.24{\pm}4.22$ IU/gram fermented substrate (gfs) and CMCase $124.04{\pm}7.78$ IU/gfs] were achieved after 48 h fermentation in solid-state medium containing apple pomace supplemented with rice husk [1% (w/w)] under optimized conditions [pH 4.5, moisture 55% (v/w), and inducers veratryl alcohol (2 mM/kg), copper sulfate (1.5 mM/kg), and lactose 2% (w/w)] (p<0.05). Koji fermentation in trays was carried out and higher enzyme activities (FPase $96.67{\pm}4.18$ IU/gfs and CMCase $146.50{\pm}11.92$ IU/gfs) were achieved. The nonspecific chitinase and chitosanase activities of cellulase enzyme extract were analyzed using chitin and chitosan substrates with different physicochemical characteristics, such as degree of deacetylation, molecular weight, and viscosity. Higher chitinase and chitosanase activities of $70.28{\pm}3.34$ IU/gfs and $60.18{\pm}3.82$ to $64.20{\pm}4.12$ IU/gfs, respectively, were achieved. Moreover, the enzyme was stable and retained 92-94% activity even after one month. Cellulase enzyme extract obtained from A. niger with chitinolytic and chitosanolytic activities could be potentially used for making low-molecular-weight chitin and chitosan oligomers, having promising applications in biomedicine, pharmaceuticals, food, and agricultural industries, and in biocontrol formulations.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.3
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• pp.247-251
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• 1999

In spite of various bio-functionalities of chitosan, the effects in vivo were still ambiguous because of its low absorption on organism. Therefore, chitosan oligosaccharides (COSs) are necessary to elucidate for an efficient utilization in vivo. COSs were prepared from chitosan using ultrafiltration membrane enzymatic reactor system with MWCO (molecular weight cut-off) 3,000 Da of membrane. Calcium absorption accelerating effect using COSs was examined by two methods, in vitro and in vivo. In vitro experiment, calcium absorption by the addition of COSs in a mixture solution of calcium and phosphate was higher approximately $50\%$ than that by control. In vivo using rats, group taken the diet contained $1\%$ COSs anil calcium chloride decreased about $75\%$ of calcium content excreted from feces, and then, showed about $15\%$ increase in breaking force of femur. These results demonstrated that COSs definitely involved in calcium metabolism in vivo.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.660-665
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• 1999

Structure of water soluble chitosan (WSC) was confirmed by Fourier transform infrared spectrometer (FT-IR), X-ray diffractometer and thermal analyser. The viscosity average molecular weight of WSC ranged from $3.0{\times}10^{4}$ to $4.5{\times}10^{4}$. Using the WSC having viscosity average molecular weight of $3.0{\times}10^{4}$, the antimicrobacterial effects against microorganism and oral microorganism showed 81.7% and 80.6% for Staphyloccus aureus and Bacillus subtilis, respectively, while the anitmicrobacterial effect exhibited 100% and 73.8% against Streptococcus mutans and Streptococcus sanguis, respectively. Therefore it is concluded that WSC is more effective against oral microorganism that microorganism in terms of antimicrobacterial effects. WSC sample with the viscosity average molecular weight of $4.5{\times}10^{4}$ exhibited a half of the antimicrobacterial effect of the low MW sample, indicating that the WSC with low MW was better than that with high MW. Chitin and chitosan showed a drastic decrease of acidity from pH 7.0 to 4.9 after 8 minute incubation time and reached an equilibrium after that. WSC, however, restrained pH of the sample from lowering up to about 16 minutes of incubation and reached an equilibrium after that. WSC obviously showed a buffering effect against pH change.

• KSBB Journal
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• v.16 no.4
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• pp.321-326
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• 2001

The change of molecular weight inside and outside a capsule produced using coencapsulating technology was investigated. Chitosan and chitosanase were enveloped in this membrane and product released was a loaded the medium by the principle of size exclusion. The leakage of substrate corresponding to the agitation speed was controlled by adjusting the alginate and CaCO$_3$ concentrations. The optimal condition of alginate concentration and agitation speed were 0.5% and 40rpm, respectively. Membrane thickness and capsules diameter were 10 $\mu$m and approx. 3.0 - 1.5 mm, respectively. Molecular weight difference by concentration and alginate viscosity were of little significance. In accordance with the molecular weight distribution versus enzyme concentration relationship, low concentration of enzyme produced high molecular weight oligosaccharides. At a 1.5 mm capsule size the product diffusion rate to outer surface highest. The molecular weight distribution of the released oligosaccharides was ranged from 1000 to 6000 Da. More than 80% of the initial activity of encapsulated enzyme retained after 8hrs of reaction.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.449-453
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• 2002

This was studied to evaluate the quality characteristics of the bread added chitosan during storage at room temperature(Temp. $27^{\circ}C{\pm}2$, RH $75%{\pm}10$). The volume of the dough was increased depending on the larger molecular weight and the higer concentration of chitosan but was decreased at 0.50% of 120 kDa chitosan. The water activity was low depending on the larger molecular weight and the higher concentration of chitosan at the early storage, but maintained constantly during storage totally. The colors of the bread was hardly affected by 30 kDa of chitosan. Textural characteristics was improved at 30 kDa and 120 kDa of chitosan. Especially, the change of the hardness were maintained lower at 30 kDa, 120 kDa of chitosan during storage than that of standard. These results showed that the quality of the bread by added 30 kDa of chitosan was improved highly.