• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.2
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• pp.198-203
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• 2000

A highly viscous biopolymer from Bacillus coagulans CE-74 was purified and its rheological properties were studied The rheological properties of biopolymers produced by Bacillus coagulans CE-74 were studied at the temperature ranges with 20~8$0^{\circ}C$, at the concentration of 0.5~4.0%, at the pH ranges from 3 to 1 and at the shear rate fo 7.34~73.38 sec-1. The apparent viscosity of biopolymer was decreased with increasing shear rate, and thereby biopolymer showed pseudoplastic characteristics. Biopolymer solution showed a characteristic of non-Newtonian fluid properties. At the concentration of 1%, the consistency index and the flow behavior index were shown at 2.64 poise. sec11 and 0.8571, respectively. All dispersions were pseudoplastic fluids described accurately by Herschel-Bulkley model. The change of the biopolymer viscosity on pH showed the highest value at the pH 7.0 and it showed lower at acidic conditon that at alkaline condition comparatively.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.808-811
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• 2001

The rheological properties of exopolysaccharide(EPS-R) produced by marine bacteria Hahella chjuensis KCTC 2395 was investigated. EPS-R solution showed a characteristic non-Newtonian behavior fluid properties. In aqueose dispersions of EPS-R 1%, consistency index(K) and flow behavior index(n) were 1,410 cp and 0.73. EPS-R solution was pseudoplastic fluid by power-low model. Rheological propertie of EPS-R was found to be influenced by the concentration of salt, pH, temperature and ionic compounds.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.581-592
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• 2000

To obtain an excellent product and decide on optimum molding conditions, it is important to establish the relationship between molding conditions and viscosity. The composites is treated as a pseudoplastic fluid, and the expansional/contractional viscosity of the fiber-reinforced polymeric composites is measured using the parallel plastometer, and the model for flow state has been simulated with the viscosity. The effects of expansional slip parameter $\alpha_{e}$, and expansional/contractional viscosity ratio ${\mu}_{\gamma}$, on the mold filling parameters are also discussed.

• Preventive Nutrition and Food Science
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• v.10 no.3
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• pp.224-230
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• 2005

The effects of low viscosity chitosan on the rheological properties of soymilk using a model system and on tofu qualities were examined. The flow behavior of soy milk with chitosan closed the Newtonian flow and stabilized according to increasing chitosan concentration. The soymilk containing $glucono-\delta-lactone$ exhibited a more pseudoplastic flow behavior compared with that of the control soymilk. The addition of low viscosity chitosan to the tofu preparation did not significantly affect its physicochemical properties. However, the results of the TEM image and instrumental textural properties showed that low viscosity chitosan affected the construction of the tofu structure. Chitosan tofu had low scores across the whole field of appearance in the sensory evaluation, and its overall eating quality was scored significantly lower. These results suggest that the addition of low viscosity chit os an affects the quality of tofu, which changes according to the degree of polymerization and concentration of chitosan.

• Korean Journal of Food Science and Technology
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• v.22 no.6
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• pp.646-650
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• 1990

To develop a new form of spice material by concentration of garlic juice, its rheological properties were investigated. In the temperature range of $15\;to\;65^{\circ}C$, the garlic juice with the solid content of $32\;to\;60^{\circ}Brix$ was considered as a pseudoplastic fluid. Flow and consistency indices of the juice interpreted by power-law equation varied from $0.9937\;to\;0.6130\;and\;0.0041\;to\;3.1886Pa{\;s^n$, respectively. Apparent viscosity was lineally decreased as shear rate was increased. Activation energy for the flow of the garlic juice changed in the range of 11,216 to 23,195 kJ/kg mol.

• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.740-743
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• 2004

Rheological properties of gamma-irradiated arrowroot starch was examined to utilize as fundamental research data far processing. Irradiated arrowroot starch solutions (3, 4, 5, 6%) were gelatinized at $95^{\circ}C$ for 40 min, and its flow properties measured using rheometer at $30^{\circ}C$ and 10 to 200 rpm rotation rate. Rheological parameters of irradiated arrowroot starch gelatinized solution were calculated using Herschel-Bulkley equation. Gelatinized arrowroot starch solutions irradiated at $0^{\circ}C$ and 5kGy showed pseudoplastic fluid behavior, while those irradiated at 10, 20, and 30kGy were the dilatant with ${\tau}_y=0$ (yield stress).

• Microbiology and Biotechnology Letters
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• v.17 no.5
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• pp.475-480
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• 1989

The extracellular polysaccharide was isolated from the culture of Ps. delafieldii and its rheological property was evaluated. The aqueous solution was extremely viscous and shows pseudoplastic behaviour. The flow behaviour index and apparent viscosity of 1 ％solution were 0.09 and 1169 mPa·s. The solution was stable over pH change but did not have thermal stability. The activation energy of flow of 1 ％ solution was 4.44 kcal/mole. The concentration dependency could be expressed double logarithmically.

• Journal of the Korean Ceramic Society
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• v.52 no.1
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• pp.56-60
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• 2015

Discontinuous, polycrystalline $Al_2O_3$-dispersed TZP fibers were prepared by the centrifugal spinning of a colloidal $ZrO_2$ sol containing Y and Al nitrates and poly(vinyl alcohol). Factors affecting the rheological properties of the sols, such as sol concentrations, aging, and the amounts and types of additives, were investigated by measuring the shear viscosities. The flow characteristics of the sols were studied in relation to the spinnability by measuring the viscosity with respect to the shear rate. The spinnability was obtained through the addition of a polymer which increases the viscosity to a range of optimum viscosity values for spinning. Aging the sols containing the additives did not noticeably change the sol viscosities at room temperature up to 30 days. The flow behavior of the spinnable sols progressively changed from nearly Newtonian to pseudoplastic with an increase in the sol concentration.

• KSBB Journal
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• v.10 no.5
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• pp.547-552
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• 1995

Some functional and rheological properties of the ${\gamma}$-polyglutamic acid(${\gamma}$-PGA) produced from alkalophilic Alcaligenes sp. were investigated. Viscosity synergism with thickening agents, capacities for gelling, entrapig of heavy metals, and flocculability of ${\gamma}$-PGA were not observed, but the relatively good compatability with various polyvalent metallic ins, excellent absorption ability and spinability were observed. The ${\gamma}$-PGA solution showed non-Newtonian flow behavior and exhibited pseudoplastic property with a yield stress at above 1% concentration. The values of flow index for 1% solution were in the range of 0.41∼0.75 showing shear rate dependency and the value of yield stress was 2.28 Pa. The value of consistency index was 0.868 Pa$.$Sn and was exponentially dependent on concentration.

• YAKHAK HOEJI
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• v.34 no.5
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• pp.302-310
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• 1990

A study has been made of the Korean bentonite aqueous suspension contrast with American bentonite by means of XRD IR swelling, gel formation and rheogram at various conditions such as concentration, temperature and pH. The Korean bentonite was identified as montmorillonite clay containig a small proprotion of crystoballite and mordenite, and its swelling power were acceptable for requirements of Korean pharmacopeia regulations though its values were not satisfied. Korean bentonite swelled to 10 times and American one did to 15 times compared to its bulkiness of powder. The rheogram of Korean bentonite suspension reveals bulged pseudoplatic flow with yield value at higher concentration and pseudoplastic flow without yield value at lower concentration. The higher the concentration, the greater were the apparent viscosity and hysteresis loop. Korean bentonite suspension showed insignificant temperature dependence on both apparent viscosity and hysteresis loop and it was more temperature dependent on viscosity but less on hysteresis loop than those of American sample. The pH dependence was so high on viscosity that apparent minimum value was near pH 7 and maximum value at pH 3 or 7. The hysteresis loop appeared minimum over the pH range 5-7 and maximum near pH 3 or 11. The Korean bentonite was inferior to the American bentonite in swelling volume, gel formation, thioxotropy, however, it would be possible to improve the quality of Korean bentonite by developing the method of purification for bentonite clay.