• Nuclear Engineering and Technology
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• v.8 no.3
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• pp.145-150
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• 1976

Alkali-treated red algae, Gracilaria sp. was irradiated with various doses of cobalt-60 gamma-rays and the yeild and properties of agar extracted from the seaweed were examined and compared with the quality of commercial agar powder after irradiation. Extraction yield of agar from irradiated seaweed was proportionally increased as the radiation dose was raised up to 2 Mrad whereas it tended to decrease slightly thereafter. Gelation ability, gelation point, gel hardness and specific viscosity of the agar were increased up to 1 Mrad and decreased at higher dose levels while its melting point, total nitrogen, crude ash and total sulfur decreased up to 1 Mrad level and remained unchanged thereafter. Irradiation of commercial agar powder caused remarkable decreases in the gelation ability, specific viscosity and gel hardness and slight decreases in the gelation point and melting point. The pattern of alterations in the properties of agar samples differed whether the polysaccharide was irradiated in free state or bound state in seaweed.

• Korean Journal of Food Science and Technology
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• v.17 no.5
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• pp.319-325
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• 1985

Agar was prepared from domestic agarophyte (Gelidium amansii) by a process of acid extraction. Optimal conditions in the acid treatment of the seaweed and the gelling properties of the agar thus prepared were investigated. The yield and gel strength of the control (the agar extracted with distilled water) showed 13,3% and 306g/$cm^2$, respectively. The yield of 38.7% was obtained when agar was extracted with 0.007N Hydorchloric acid while the gel strength of agar,511g/$cm^2$ was observed with the agar extracted with 0.005N Hydorchloric acid solution. The agar extracted with hydrochloric acid solution showed excellent properties of agar at the acid concentration range 0.005N-0.01N The cooking time of 60 min. was found to be effective to the yield and also to the gelling property of the agar and the cooking longer than 60 min. was proved to be destructive to agar. In general, yield and gelling properties of the agar obtained showed a close relation to the acid concentration and cooking time, but no consistent influence on the contents of ash and sulfur trioxide.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.5
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• pp.681-688
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• 1996

To investigate the effort of drying methods on the physicochemical properties of agar, gel strength, viscosity, melting and setting point, and phase transition by differential scanning calorimetery (DSC) during its heating were determined. In addition the structural differences of agar powder by scanning electron microscope (SEM) was examined. The most shortest onset temperature of gel strength increase was extruding method among any other methods. Viscosity of agar with hot air method, 400.00 cps at $45^{\circ}C$, was markedly increased, but with spraying and extruding ones were little change. The melting and setting point, and the temperature for maximum endothermic and enthalpy for agar with extruding one, $80.01^{\circ}C,\;36.05^{\circ}C\;and\;61.72^{\circ}C,\;0.73\;cal/g$, respectively, were lowest among the drying ones. But in the case of reheating after gelling, there were little change in all methods. Observing the surface structure of agar with SEM, extruding method showed the most unstable with absorptive property.

• Korean Journal of Food Science and Technology
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• v.23 no.2
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• pp.217-223
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• 1991

A capillary method was used to evaluate the properties of mass transfer process and diffusion coefficients in the gel food. Amaranth dye was selected as a diffusant material to visualize the degree of diffusion procedure easily. After contacting cylinder containing agar gel with amaramth dye solution for some hours, the gel was cut to five segments by 0.5 cm in length. The diffusant concentration from the segments were measured by the spectrophotometer at 523 nm. Prediction models for the diffused quantities in gel food were established by the regression program of SPSS package program. Generally, diffusion coefficient can be calculated by Fick's second law, however, it will be determined by using numerical analysis method more easily. Finally the diffusion coefficients in this research were calculated by arithmetic mean of the measured values. As raising gel agent concentration, the mean diffusion coefficient tended to decrease because the obstruction effect came to become significant.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.3
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• pp.142-148
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• 2007

An agar-degrading marine bacterium, strain AS-3 was isolated from the seawater. The strain AS-3 was identified as Algibacter lectus AS-3 by 16S rDNA sequence. The optimum medium for agarase activity of the isolated strain was determined to be marine medium, marine broth 2216 containing 0.1% agar as carbon source. An extracellular agarase was purified 6.9-fold from the culture supernatant by ammonium sulfate precipitation, ion exchange chromatography and gel filtration methods. The optimum pH and temperature for this enzyme were 7.0 and $40-50^{\circ}C$, respectively. Antioxidative activity of the strain AS-3 was 62.4% in the supernatant cultured for 12 h.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.423-427
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• 1997

The effect of different treatments on the quality and yield of purified agar produced from Gelidium amansii has been studied, and the extraction condition ol agar produced from G. amansii has been examined. The contents of ash, sulfate in agar produced from g. amansii collected from different places were $2.63\~2.92\%\;and\;1.38\~1.78\%$, respectively. Yields and gel strength of agar produced from G. amansii collected from different places were $31.6\~46.8\%\;and\;496\~887g/cm^2$, respectively. It was effective to extract agar at $120^{\circ}C\;for\;2\~3hrs$. Agar was purified by D.W. washing, EDTA washing, chitosan treatment, CPC treatment, PEG treatment, ethanol precipitation, acetone precipitation and propanol precipitation. The mineral contents of agar produced from Gelidium amansii were Na (2934ppm), Ca (2472ppm), Mg (2259ppm), K (2527ppm), P1(81.1ppm), Fe (66.4ppm), Al (71.7ppm), Zn (29.7ppm) and Pb (ND: not detected), respectively.

• Journal of the Korean Society of Visualization
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• v.8 no.4
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• pp.54-59
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• 2010

A laser moxibustion therapy device having effect similar to that of traditional moxibustion is being developed using 1064 nm infrared laser. The therapy device allows direct interaction of laser light with the tissue rendering temperature distribution both on the skin surface and deep under the skin. We made a device that could measure temperature of deep under the surface of agar gel tissue phantom using thermocouples. A thermal imaging camera was used to verify results from the temperature measurement device. We compared the characteristics of heat transfer inside the tissue phantom during moxibustion and laser irradiation. The temperature distribution measured by thermocouples was found to be similar to that of distribution given by thermal imaging camera.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.6
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• pp.387-393
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• 2007

We examined the conditions for separating and preserving the male and female gametophytes of Kjellmaniella crassifolia. The highest percentage of zygote germination (85%) was on semi-solid medium composed of 1.0% transfer gel agar at $15\;^{\circ}C$ and $20\;{\mu}mol/m^2/s$ after a 4-week culture. Zygote germination in PESI liquid medium was 93.5% at $20\;^{\circ}C$ and $20\;{\mu}mol/m^2/s$. The maximum zygote growth was $252{\pm}19.7\;{\mu}m$ on 1.0% transfer gel agar at $15\;^{\circ}C$ and $40\;{\mu}mol/m^2/s$ after 5-week culture, and was $76.7{\pm}2.8\;{\mu}m$ in PESI liquid medium at $20\;^{\circ}C$ and $40\;{\mu}mol/m^2/s$. The respective numbers of separated male and female gametophytes from germinated zygotes were 157 and 93 on 1.0% transfer gel agar and 14 and 28 in PESI liquid medium. The maximum growth of separated male and female gametophytes was $575{\pm}28.3\;{\mu}m$ at $5\;^{\circ}C$ and $60\;{\mu}mol/m^2/s$ and $686{\pm}35.4\;{\mu}m$ at $20\;^{\circ}C$ and $20\;{\mu}mol/m^2/s$ in PESI liquid medium after 3 weeks, respectively. The highest percentage fertilized was $93.3{\pm}5.8%$ at $15\;^{\circ}C$ and $20\;{\mu}mol/m^2/s$ in PESI liquid medium. These results show that the best conditions for the separation and preservation of gametophytes (male and female) consisted of culturing on 1.0% transfer gel agar at $15\;^{\circ}C$ and $20\;{\mu}mol/m^2/s$.

• Korean journal of food and cookery science
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• v.4 no.1
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• pp.17-26
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• 1988

The polysaccharide produced by pseudomonas elodea, Gellan gum, was rheologically characterized, compared with agar. Rheological properties were determined from the change in the value of intrinsic viscosity with the pH and salt concentration. At the range of pH 2∼ll and salt 0∼0.16M KC1, the intrinsic viscosity of Gellan gum ranged from 8.8 to 21.2dl/g and agar ranged from 1.97 to 11.46d1/g. In the absence of salt, the intrinsic viscosity of Gellan gum increased as the pH of solution increased up to neutral pH then decreased slightly at alkaline pH, whearas the intrinsic viscosity of agar increased as the pH of solution increased up to pH 9 then decreased slightly. Intrinsic viscosity of Gellan gum and agar decreased with an increase in salt concentration. The chain stiffness parameter for the Gellan gum was 0.033. The overlap parameter of Gellan gum and agar were 0.047g/dl and 0.087g/dl, respectively. Gellan gum and agar were shear rate dependent or pseudoplastic. The yield stress and proportionality constant of Gellan gum increased slightly as the concentration increase, on the other hand, the shear index of Gellan gum showed a maximum at 0.75g/dl and gradually decreased as the concentration increase. The apparent viscosity of Gellan gum and agar decreased as the temperature increase. A lower concentration of the divalent cations calcium and magnesium is required to obtain maximum gel strength than for the monovalent cations sodium and potassium.

• Korean Journal Plant Pathology
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• v.1 no.1
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• pp.61-66
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• 1985

Seventy-one strains collected from Korea were classified into three serovars (designated A, B-I and B-II) by using agar gel diffusion test with the antisera produced against Xanthomonas campestris pv. oryzae isolates Q7472 and Q7502. Of 71 isolates tested, 65 isolates belonged to serovar A, 5 isolates were serovar B-I, and one isolate was serovar B-II. The isolates of serovar B-I and B-II could be distinguished clearly from those of serovar A showing marked autoagglutination. Xanthomonas campestris pv. oryzae was serologically diagnosed in rice leaves by agar gel diffusion tests, possibly being distinguished from Xanthomonas campestris pv. olyzicola and E. herbicola. The pathogen could be also serologically detected from the extracts of diseased leaves, squeezed immediately, heated at $100^{\circ}C$ or incubated in PSA. Serological detection of Xanthomonas campestris pv. oryzae is a more reliable and less time-comsuming method.