食品中致病菌γ射线辐照杀菌效果影响因素研究

为更好地保证食品的辐照杀菌效果，以纯培养的李斯特菌、沙门氏菌、大肠杆菌O157∶H7为研究对象，分别将其接种于番茄、胡萝卜、水煮杏仁、冷却肉、冷冻肉、芥蓝豆、盒装豆腐、杏干、营养肉汤、芹菜花生冷食材等介质中，研究辐照剂量、菌种类型、介质类型、介质温度、包装类型等条件对γ射线辐照杀菌效果的影响，明确环境条件对致病菌辐照敏感性的影响。结果表明：同一种介质中不同致病菌对辐照的敏感性不同，其中大肠杆菌O157∶H7对辐照最为敏感；在大多数介质中，沙门氏菌对γ射线辐照的敏感性略高于李斯特菌。对于同一种致病菌，介质中的水含量和介质的成分对辐照效果有较明显的影响，水分含量高的介质中致病菌对辐照更为敏感，肉中的致病菌较蔬菜中的致病菌对辐照更具抗性；低温辐照，尤其是冷冻条件下辐照能增加致病菌对辐照的抗性；当有氧气存在时，致病菌对辐照的敏感性相对增加。

Influence Factor of Bactericidal Effect of Pathogenic Bacteria in Food by γ-ray Irradiation

In order to make the pathogenic bacteria inactivation of irradiation better on food processing, Listeria, Salmonella and e. coli O157∶H7 were inoculated into tomato, fresh-cut carrot, packaged tofu, nutrient broth, blanched almonds, blanched peanut and celery mixture, blanched mustard green and soybean, dried apricots, chilled pork and frozen pork respectively, and the influence factors, such as irradiation dose, medium temperature, type of strain, medium type and packaging type, on pathogenic bacteria inactivation were studied. The results show that different mediators and pathogenic bacteria species have great influence on pathogenic bacteria inactivation. The e. coli O157∶H7 is the most sensitive (a higher sensitivity means a stronger pathogenic bacteria inactivation), and Salmonella is more sensitive than Listeria in most mediators. As for the same kind of pathogenic bacteria species, water content and component of mediator are significant factors for pathogenic bacteria inactivation. Higher water content can enhance pathogenic bacteria inactivation, pathogenic bacteria in pork is harder to be killed than that in vegetables. The resistance of pathogenic bacteria in freezing medium to irradiation increases, and the sensitivity of pathogenic bacteria relatively increases in the presence of oxygen.