67C-3 |
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K. B. SONG1, M. Lee2, and S. Lee2. (1) Dept. of Food Science & Technology, Chungnam National Univ., College of Agriculture & Life Sciences, 220 Gung-dong, Yuseong-gu, Daejon, 305-764, South Korea, (2) Chungnam National University Soy protein isolate (SPI) films have been used as food package, yet known to be ineffective moisture barrier due to hydrophilic nature. Therefore, to improve water-resistance properties of SPI films, cross-linking agents or ionizing radiation have been attempted. Our objectives were to elucidate the effect of g-irradiation on the physicochemical properties of SPI films and to improve the water vapor permeability and tensile strength of the films. Film forming solutions were prepared by dissolving SPI in distilled water (5 g/100 mL). Glycerol (5%) was added as a plasticizer. Film-forming solutions were conditioned and irradiated at 0, 4, 16, 32, and 50 kGy using a 60Co gamma irradiator. Film forming solutions were then cast and dried films were peeled intact from the casting surface. Film tensile strengths and elongation at break were determined. Water vapor permeability and color values of the films were determined. Scanning electron microscopy was used to characterize the microstructure of the films. Gamma-irradiation of SPI solutions caused the disruption of the ordered structure of the soy protein molecules on a SDS-PAGE study. Gamma-irradiation decreased the viscosity due to cleavage of the polypeptide chains. Gamma irradiation treatment decreased water vapor permeability of SPI films by 13% and increased mean tensile strength to 3.24 MPa at 50 kGy, compared with 1.59 MPa of the control film. Radiation also affected yellow color, resulting in a significant increase in Hunter +b values. Microstructure observed by scanning electron microscope showed that irradiated soy protein isolate films had a smoother and glossy surface than the control film. These results showed that g-irradiation treatment of the SPI solutions caused the change in water vapor permeability and tensile strength of the films. Therefore, g-irradiation can be a useful tool as a cross-linking agent to improve functional properties of SPI films.
Session 67C, Food Chemistry: Food analysis, irradiation and toxicology
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