30C-1 |
Effect of gamma-irradiation on the physicochemical properties of blood plasma proteins |
K. B. SONG1, S. Lee, S. Lee, and N. Sun. (1) Food Science and Technology, College of Agriculture, Chungnam National University, 220 Gungdong, Yusungku, Taejon, 305764, South Korea Radiation treatments of biological materials have been applied to food products. Radiation causes the irreversible changes of protein conformation at the molecular level. The chemical changes are fragmentation, cross-linking, and aggregation by oxygen radicals generated in the radiolysis of water. Therefore, oxygen radicals could modify structure of proteins, which resulted in changes of physicochemical properties. Our objective was to examine the effect of gamma-irradiation on the physicochemical properties of blood plasma proteins and to improve its safety since gamma-irradiation eliminates the microbial contamination. Plasma protein powder samples wrapped with PE films and solutions of proteins in 20 mM phosphate buffer (pH 7.0) were irradiated using 60Co as source with 0, 1, 5, 7, and 10 kGy, respectively. To determine the change in the secondary structure of proteins irradiated, circular dichroism spectroscopy was performed using a spectropolarimeter. SDS-PAGE was performed to determine the molecular weight distribution of proteins. Solubilities of plasma protein powders irradiated were measured. Viscosities were measured using a Brookfield viscometer. Total bacterial count was determined before and after irradiation of blood plasma proteins. Gamma-irradiation of proteins caused the disruption of the ordered structure of protein molecules. Circular dichroism study showed that increase of radiation up to 10 kGy decreased the ordered structure of proteins with concurrent increase of aperiodic structure content. SDS-PAGE study showed that radiation caused initial fragmentation of proteins up to 5 kGy and subsequent aggregation due to cross-linking of protein molecules at 7 or 10 kGy doses. Solubilities and viscosities varied depending on radiation doses. Radiation above 5 kGy completely inhibited the microbial growth in the plasma protein powders. These results suggest that gamma-irradiation of proteins caused the change of secondary structure of proteins, resulting in change of physicochemical properties of proteins, and could eliminate the microbial contamination and improve the utilization of plasma proteins.
Session 30C, Food Chemistry: Proteins
|