• Korean Journal of Food Science and Technology
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• v.39 no.5
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• pp.521-526
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• 2007

In this study, we prepared methyl cellulose (MC) and hydroxypropylated methyl cellulose (HPMC) films with polyethylene glycol (PEG) or polyphosphates as elongation enhancing materials, and with lipid layers as moisture barrier materials. We then determined their physical properties and compared the data with target physical properties such as a tensile property of 13.0 MPa, elongation of 130%, and water vapor permeability of $3.47{\times}10^{-2}ng{\cdot}m/m^2{\cdot}s{\cdot}Pa$. The PEG and polyphosphates were required for enhancing elongation, while the coating method seemed better than the emulsion method when applying the lipid layers. With respect to elongation, the MC films were better than the HPMC films.

• Korean Journal of Food Science and Technology
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• v.43 no.3
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• pp.321-328
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• 2011

Edible films were developed from jujube (Zizyphus jujube Miller) using depolymerization processes of ultrasound and high-pressure homogenization. A 4.6% (w/w) jujube hydrocolloid was treated by ultrasound (600W, 20 min) or homogenized at high pressure (172 MPa, 6 s) and mixed with whey protein isolate, glycerol, xanthan, and sucrose esters of fatty acids to form film-forming solutions from which films were formed by drying. The film prepared by highpressure homogenization (HPH film) produced more homogeneous films without particles than those prepared without depolymerization or with the ultrasound treatment. HPH films possessed the highest tensile strength (4.7MPa), the lowest water vapor permeability ($2.9g{\cdot}mm/kPa{\cdot}h{\cdot}m^2$), and the most uniform and dense microstructures among the films. Flavor profiles of jujube powder and the films were distinguishable. Heat seal strength and oxygen permeability of the HPH films were 44.4 N/m and $0.025mL{\cdot}{\mu}m/m^2$/day/Pa, respectively. Antioxidant activities of jujube power and HPH films were not significantly different.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.9
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• pp.1251-1255
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• 2006

To improve the water resistance and physical properties of soy protein isolate (SPI)-coated paper, effects of concentrations of soy protein isolate and plasticizer were examined. Physical properties such as elongation strength (ES), elongation rate (E), water vapor permeability (WVP), and water solubility (WS) were evaluated. The film made from 5% soy protein isolate (SPI) and 40% glycerol (plasticizer) suggested a good application for a film preparation. SPI coated paper showed the highest ES (21.62 MPa) and the lowest WVP $(2.06ng{\cdot}m/m^2{\cdot}s{\cdot}Pa)$ and WS (1.17%). This study suggested that soy protein isolate (SPI) can be used as a coating material for the coated paper to improve the water resistance.

• Journal of the Korea Institute of Building Construction
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• v.17 no.5
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• pp.437-444
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• 2017

In the composite waterproofing method in which a polyurethane coating waterproofing material is applied on the modified asphalt waterproofing sheet, the organic solvent is diluted in the coating waterproofing material in order to improve the workability. However, since the organic solvent is not volatilized before the curing of the polyurethane coating waterproofing material, the organic solvent causes dissolution of asphalt layer, thereby causing oil leakage. As a result, a polyamide film having a high dissolution resistance property was laminated on modified asphalt sheet, and through testing the dissolution resistance was visually confirmed and quantitative analysis of the polyamide film by SEM-EDX analysis was also used to confirmed the dissolution resistance of the polyamide film.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1097-1106
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• 1998

Biodegradable edible films were prepared from rice protein concentrates (RPC) made from rice wine meal by alkaline extraction and isoelectric precipitation. The effect of film forming solution pH and plasticizers were studied, and cross-linkers were added to improve mechanical properties and water vapor permeabilities (WVP) of films. Films could be formed within pH $8{\sim}11$ with tensile strength (TS) of 4.3{\sim}5.7\;MPa$. Films produced under pH 11 had the highest TS (5.7 MPa) and the lowest WVP $(0.44\;ng{\cdot}m/m^2{\cdot}s{\cdot}Pa)$. Added glycerol, polyethylene glycol 200 (PEG) and its mixture (GLY:PEG=50:50) as plasticizers also affected the mechanical properties and WVP of films. TS and elongation at break (E) of films at various plasticizer levels were $5.5{\sim}1.0\;MPa$ and $3.6{\sim}24.3%$, respectively. At the same plasticizer concentration, the highest TS was observed when glycerol was used whereas the highest E was measured when mixture was used as plasticizer. WVPs of films with thickness of $60\;{\mu}m$ were $0.39{\sim}0.54\;ng{\cdot}m/m^2{\cdot}s{\cdot}Pa$. WVP of films decreased as the ratio of glycerol/PEG 200 was decreased, and WVP increased as the total amount of plasticizer added to the films increased. Film strength was improved by the addition of small amount of sodium hydrogen sulfate, succinic anhydride, ascorbic acid and citric acid, whereas TS of films containing $0.5{\sim}2.0%$ of NaCl and $CaCl_2$ were lower than those without the salts. The highest TS (6.3 MPa) was achieved with films containing 0.1% of succinic anhydride.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.1
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• pp.9-15
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• 2017

To identify applicability for packaging material of polyvinyl alcohol (PVA)/boric acid (BA) coating solution with highly-enhanced water vapor and oxygen barrier properties, the PET/PVA-BA/OPP multi-layer films were prepared through comma coating and lamination process. The oxygen and water vapor permeabilities, and tensile strength of as-prepared multi-layer films were investigated before and after pressure cooker test (PCT). Although oxygen and water vapor permeabilites, and mechanical properties of PET/PVA-BA/OPP multi-layer films was decreased after PCT, their properties were highly enhanced as increase of BA contents in PVA matrix. This is strongly related with enhanced cross-linking density in PVA-BA layer. In storage test of seasoned-laver, the PET/PVA-BA/OPP multi-layer films were comparatively effective to suppress the increase in peroxide value originating from oxidation of seasoned-laver. Comparing the commercially available PP/Al-metallized PP for seasoned-laver packaging, however, PET/PVA-BA/OPP multi-layer films did not show any advantage in water activity. This is due to higher water vapor permeation properties of as-prepared multi-layer films. Therefore, further studies are required to enhance the water vapor permeation in PET/PVA-BA/OPP multi-layer films.

• Food Science and Preservation
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• v.20 no.1
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• pp.14-22
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• 2013

The effects of the initial storage temperature and the PA film packaging on the extension of the shelf-life and the improvement of the postharvest storage quality of muskmelons were studied during their storage. Their storage quality was tested as follows: PA-film-wrapped muskmelons, stored at $2^{\circ}C$ or $7^{\circ}C$ for 30 days after their harvest, were kept at $10^{\circ}C$ for 27 days (total: 57 days). On the fifth day of storage at $10^{\circ}C$ (35th day overall), the weight loss reached 6.4% in the 7-control. However, the 2-PA showed the smallest loss of 2.2%. The soluble solids content and the acidity that were measured before the storage were $10.8^{\circ}Brix$ and 0.26% in all the groups. After 27 days of storage at $10^{\circ}C$ (on the 57th day overall), the values were highest in the 2-PA group with $9.7^{\circ}Brix$ and 0.15%, respectively. Microorganisms were not detected at first; but on the fifth day of storage at $10^{\circ}C$ (35th day overall), their values were 3.87 and 2.68 log CFU/g in the seven-control and the 2-PA, respectively. In other words, the 2-PA was found to be more effective in inhibiting microbial proliferation. In relation to sensory properties such as appearance, flavor, sweetness and chewiness, the 2-PA was superior to the other groups and was found to be most effective in improving the storability of muskmelons. In conclusion, it was found that low-temperature injury and fast storage quality deterioration did not occur in film-wrapped muskmelons that were stored at $2^{\circ}C$ for 30 days after they were harvested.

• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.452-459
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• 1997

Effect of extraction pH on mechanical properties such as tensile strength (TS) and elongation (E) and on water vapor permeability (WVP) of soybean protein isolate (SPI) edible films extracted from soybean meal was investigated. Five pHs, acidic range (pH 2.0 and pH 3.0), neutral range (pH 7.0) and alkalic range (pH 10.0 and 12.0), were used to extract SPI. TS of the film extracted at pH 7.0 was the lowest, and WVP of $SPI_3$ (SPI extracted at pH 3) film was the lowest value among the films. The WVP of $SPI_3$ films was $3.349\;{\times}\;10^{-10}\;g{\cdot}m/m^2{\cdot}s{\cdot}Pa$ and increased to $3.871\;{\times}\;10^{-10}\;g{\cdot}m/m^2{\cdot}s{\cdot}Pa$ as film thickness increased from $55\;{\mu}m$ to $72\;{\mu}m$ thickness. Three different plasticizers (glycerol, polyethylene glycol and propylene glycol) were used for $SPI_2$ (SPI extracted at pH 2) film. TS of $SPI_2$ films was 12.297 MPa and decreased to 1.356 MPa for glycerol and showed the same trend in other two plasticizers. The SPI films extracted at acidic range were shown higher mechanical properties and lower water vapor permeabilities than those of extracted at neutral and alkalic ranges. The difference of SPI film properties seemed to be attributed by 11S/7S ratio as well as protein content.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.6
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• pp.727-731
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• 2009

Effects of various plasticizers (1.5%) such as glycerol, sorbitol, fructose, sucrose, and polypropylene glycol, and ferulic acid on the physical properties of Gelidium corneum (GC) film were examined. GC films containing plasticizer and ferulic acid were prepared by incorporating various amounts (10, 30, 50, 70, 100 mg/100 mL) of ferulic acid into the film. Water vapor permeability (WVP) of the GC film varied depending on the type of plasticizer, and among them the film containing sucrose had the lowest WVP. Tensile strength (TS) and % elongation (%E) of the film were in the range of $1.29{\sim}11.29$ MPa and $5.55{\sim}36.44$ %, respectively, and the WVP values were of $1.30{\sim}1.60\;ng\;m/m^{2}sPa$. In addition, the GC films were prepared using ferulic acid as a cross-linking agent. WVP of the film decreased with the addition of ferulic acid, and the film containing 30 mg ferulic acid had the lowest WVP value. TS value of the GC film containing 10 mg of ferulic acid was significantly higher than that of the control. However, further increase of ferulic acid concentration decreased the TS value. Therefore, 10 mg of ferulic acid was determined to be the optimal concentration for the film.

• Korean Journal of Food Science and Technology
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• v.44 no.2
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• pp.162-167
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• 2012

Edible biopolymer films were developed from hijiki ($Hizikia$ $fusiforme$), using a high-pressure homogenization (HPH). Effects of pressure and pass number of HPH on color, tensile, moisture barrier properties, flavor profiles, and microstructure of hijiki films were investigated. A hydrocolloid of hijiki was processed by HPH at 69, 103, or 152 MPa with 1, 2, or 3 passes. A hijiki-base film was formed by drying a film-forming solution which was prepared by mixing of the HPH-processed suspension with glycerol and Polysorbate 20. Tensile strength and elastic modulus increased with increasing HPH pressure. Uniformity of the films increased as the pressure of HPH with 1 pass increased and the number of pass increased at 152 MPa. Water vapor permeability ($2.1-3.3g{\cdot}mm/kPa{\cdot}h{\cdot}m^2$) and water solubility (0.4-1.0%), which are relatively low compared to those of many other edible films, show the potential that hijiki-base films are applied to the range of low to intermediate moisture food as wrapping or coating.