• Macromolecular Research
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• v.10 no.6
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• pp.325-331
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• 2002

Phase behavior of a PEO-PPO-PEO (Pluronic P103) triblock copolymer in water is investigated using small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), dynamic light scattering (DLS) and rheology. Pluronic P103 shows apparent two gel states in different temperature regions. The first sol-to-gel transition at a lower temperature (i.e., the hard gel I state) turns out to be the hexagonal microphase as evidenced by the combined SANS and SAXS and the frequency dependence of both G′ and G" in rheology. In contrast to the hard gel I, the second sol-to-gel transition (i. e., the hard gel II state) at a higher temperature represents the block copolymer micelles in somewhat disordered state rather than the ordered state seen in the hard gel I. Moreover, turbidity change depending only on the temperature with four distinct regions is observed and the large aggregates with size larger than 5,000 nm are detected with DLS in the turbid solution region. Based upon the present study, two different gelation mechanisms for aqueous PEO-PPO-PEO triblock copolymer solutions are proposed.

• Polymer(Korea)
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• v.24 no.6
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• pp.787-793
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• 2000

The acrylonitrile copolymer/dimethylformamide (DMF) solutions were prepared to investigate the gelation behavior and critical gel concentration (c＊). Gelation is rapidly progressed with the increase of molecular weight of copolymer, but significantly delayed with supercooling temperature and comonomer contents. The c＊ behavior showed contrary trend against gelation behavior. In dynamic viscoelastic test, two glass-transition region were observed in film obtained from gelled solution whereas one glass-transition in film obtained from true solution. This result supports the idea that an ordered junction zone is formed by the dipole-dipole interaction of intermolecularly neighboring stereo-regular parts of atactic acrylonitrile copolymer chains due to a nucleation process in the solution.

• Korean Journal of Food Science and Technology
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• v.25 no.4
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• pp.404-406
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• 1993

In order to detect the gelation of ultrahigh temperature (UHT) treated market milks during storage at 20+1C, the free amino groups were quantified with 2,4,6-trinitrobenzene sulfonic acid, and the measurement of pH values and the alcohol test were monthly carried out. The average tree amino groups were $0.94{\sim}1.11{\mu}M$ at 1 month, $1.95{\sim}2.17{\mu}M\;at\;5{\sim}6$ month and $4.95{\sim}6.36{\mu}M$ at 12 month. The pH values at the same time as above were $6.72,\;6.49{\sim}6.55\;and\;6.14{\sim}6.16$, respectively. The alcohol test showed positive results at $5{\sim}6$ month, which could indicate the casein instability and beginning of gelation. These results suggest that the gelation of UHT market milks could he predicted through checking some chemical parameters weekly and be helpful for quality control.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.7-11
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• 2001

The influence of temperature and calcium concentration on the gelation kinetics of purified Aigeok system has been investigated by small deformation oscillatory measurement. DE(degree of esterification) of the present sample was indicated of low methoxyl Aigeok polysaccharide by FT-IR. The calcium induced gelation of Aigeok has been studied. Both moduli reached the saturation value during the period of experiments. Rate constant increased with increasing calcium concentration, however above 4.08 mM calcium chloride caused a sudden drop in gel strength. The experimental result that the decrease in gel strength at high calcium concentration was seems to be phase separation or competitive inhibition between calcium ions. The storage and loss shear moduli decreased with increasing temperature. The rate constant of Aigeok system remarkably dropped above $35^{\circ}C$. Thus hydrogen bonding is prior to hydrophobic interaction for Aigeok molecule.

• The Journal of the Acoustical Society of Korea
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• v.21 no.3E
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• pp.126-131
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• 2002

Ultrasonic measurements are made in egg white to study the properties of the solution of the natural protein. The high-Q ultrasonic resonator method is used to get the ultrasonic absorption spectra over the range 0.2-10 ㎒ at 20℃. It is proportional to the 1.25th power of the frequency. The gelation process caused by heat is studied from the change in the velocity and the absorption. at 3 ㎒ using the pulse echo overlap technique over the range of 10-80℃. The absorption decreases with increasing temperature up to 60℃ where it turns up sharply and rapidly increases thereafter. The strong absorption in the gel region is described by the interaction between the solution and the network structure made of protein. Very slow variation in time elapse is observed after the temperature is quickly raised. It would be a real-time observation of the network building process and the characteristic time for the process is shown to be 400 min. A hysteresis phenomenon with respect to the temperature is observed. This phenomenon is associated with the memorizing effect of the network structure of protein of the gel.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.953-959
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• 2004

BaTiO$_3$ powder has been applied in so much electronic ceramics. Therefore, as recent, the method to add or coat additive will be needed BaTiO$_3$ powder. As a kind of the method, the coating of BaTiO$_3$ powder was considered. In this study, during BaTiO$_3$ powder was coated by BaTiO$_3$ sol, gelation path was experimented. Standard coating condition was set for homogeneous coating. The phase of the gel was deferent by gelation path. It was confirmed the amorphous gel was made in BaTiO$_3$ phase easily at low temperature. In the amorphous gel, particle growth was shown at 900$^{\circ}C$, because crystallization temperature was low. The optimal ratio of sol and powder was at 10 vol% for the homogeneous coating.

• Food Science of Animal Resources
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• v.18 no.3
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• pp.209-215
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• 1998

Effects of protein concentration, ionic strength, pH, and temperature range on the heat-induced denaturation of salt soluble protein extracted from spent layer meat were investigated. Viscosity of salt soluble protein heated at 65$^{\circ}C$ for 30 min began to increase sharply above 7 mg/ml of breast protein concentration, and above 21 mg/ml of leg protein concentration, respectively. Both turbidity and viscosity showed the highest value in cooked protein solution with pH 6.0 and 1% NaCl. The turbidity of salt soluble protein started to increase continuously from 40$^{\circ}C$ to 80$^{\circ}C$. The viscosity increased rapidly from 45$^{\circ}C$ to 60$^{\circ}C$ in breast protein, and increased from 50$^{\circ}C$ to 55$^{\circ}C$ in leg protein, respectively, and then kept relatively constant. Breast protein had higher viscosity than leg protein during heat-induced gelation. Therefore, salt soluble protein from spent layer meat was associated with denatured protein (turbidity change) prior to gelation (viscosity change) during heating. Breast protein showed lower thermal transition temperature, and better gel formation than leg protein during heating.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.6
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• pp.550-552
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• 2006

Periosteum-derived progenitor cells (PDPCs) were isolated using a fluorescence-activated cell sorter and their chondrogenic potential in biomaterials was investigated for the treatment of defective articular cartilage as a cell therapy. The chondrogenesis of PDPCs was conducted in a thermoreversible gelation polymer (TGP), which is a block copolymer composed of temperature-responsive polymer blocks such as poly(N-isopropylacrylamide) and of hydrophilic polymer blocks such as polyethylene oxide, and a defined medium that contained transforming growth $factor-{\beta}3\;(TGF-{\beta}3)$. The PDPCs exhibited chondrogenic potential when cultured in TGP. As the PDPCs-TGP is an acceptable biocompatible complex appropriate for injection into humans, this product might be readily applied to minimize invasion in a defected knee.

• Food Science and Biotechnology
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• v.14 no.3
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• pp.340-343
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• 2005

Surimi samples were prepared with the addition of three different sugars (sucrose, glucose, and fructose) at 8% and the thermal gelation of surimi sols was investigated by small-deformation oscillatory measurements of storage (G') and loss (G") moduli. The magnitudes of G' at $10^{\circ}C$ were much greater than G" over the entire range of frequency (${\omega}$), with little dependence on ${\omega}$. In general, G' values of surimi sol containing sucrose during heating (from 10 to $95^{\circ}C$) was pronounced than those of glucose and fructose, showing the following order: sucrose>glucose>fructose. The transition peaks of surimi sols containing sugars were in the temperature range of $34.8-37.4^{\circ}C$.

• Food Science of Animal Resources
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• v.34 no.5
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• pp.692-699
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• 2014

The aim of this study was to apply the external ionic gelation using an atomizing spray device comprised of a spray gun to improve the viability of Lactobacillus plantarum DKL 109 and for its commercial use. Three coating material formulas were used to microencapsulate L. plantarum DKL 109: 2% alginate (Al), 1% alginate/1% gellan gum (Al-GG), and 1.5% alginate/3% gum arabic (Al-GA). Particle size of microcapsules was ranged from 18.2 to $23.01{\mu}m$ depending on the coating materials. Al-GA microcapsules showed the highest microencapsulation yield (98.11%) and resulted in a significant increase in survivability of probiotic in a high acid and bile environment. Encapsulation also improved the storage stability of cells. The viability of encapsulated cells remained constant after 1-mon storage at ambient temperature. The external ionic gelation method using an atomizing spray device and the Al-GA seems to be an efficient encapsulation technology for protecting probiotics in terms of scale-up potential and small microcapsule size.