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Inactivation of foodborne bacteria by E-beam technology |
A. F. MENDONCA, Dept. of Food Science & Human Nutrition, Iowa State Univ., 3399 Food Sciences Bldg., Ames, IA 50011-1061 Electron beam irradiation is highly effective for inactivating foodborne microorganisms to improve the microbial safety and shelf-life of food. As with other types of ionizing radiation such as gamma rays and x-rays, electron beam irradiation inactivates microorganisms by breaking molecular bonds in their DNA. Irradiation-induced damage to DNA is caused by direct deposition of energy in the bacterial cell or via production of free radicals from the radiolysis of water. The antimicrobial action of electron beam irradiation against foodborne bacteria is affected by several factors including, irradiation dose, temperature, population and types of bacteria, physiological state of the organism, gaseous environment and food preservation method. Therefore, careful consideration of these factors is crucial for optimizing the application of electron beam technology to destroy bacteria in food. The sequential application of certain food processing treatments (eg. heat pasteurization, acidification, high pressure, and bacteriocins) and electron beam technology allows the use of lower irradiation doses for inactivation of foodborne bacteria. Good food manufacturing practices and proper sanitation can reduce microbial contamination, which also permits the inactivation of bacteria via use of lower irradiation doses. This in turn minimizes negative changes in the desirable sensory characteristics of food. Depending on the level used, certain food additives with antioxidant properties may protect foodborne bacteria from the lethal effects of electron beam irradiation by scavenging free radicals. Also, adaptation of foodborne bacteria to certain environmental stresses may enhance their ability to survive following irradiation treatment. Further research is needed to determine the resistance of foodborne pathogenic bacteria to electron beam irradiation following their adaptation to environmental stresses commonly encountered in food processing environments. Results of this type of research can help food processors in designing irradiation treatments with an extra margin of safety against foodborne pathogenic bacteria.
Session 5, E-Beam technology: Where are we in terms of the science?
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