介质阻挡放电对橙汁灭菌及其品质的影响

为了消除加热杀菌的不利影响,开发和研究冷灭菌技术日益受到人们的重视。为此,利用大气压空气中平行平板介质阻挡放电(DBD)产生的低温等离子体对橙汁灭菌效果及品质的影响进行了研究。选取了3种具有代表作用的微生物(革兰氏阳性的金黄色葡萄球菌、革兰氏阴性的大肠杆菌和典型真菌的代表白色念球菌)。研究了不同处理时间下低温等离子体对掺入橙汁中微生物的灭活效果。此外,还研究了低温等离子体对橙汁货架期的影响,并且利用一系列生物医学检测手段和仪器(2,4二硝基苯肼比色法、氢氧化钠滴定法、数字阿贝折射仪、pH计和分光光度计)对经低温等离子体处理前后的橙汁维生素C的质量浓度、总酸、糖度(°Brix)、pH值和浊度进行了测量,考察了pH值对微生物的灭活效果。实验结果表明:低温等离子体可以快速有效地杀灭掺入橙汁中的微生物(金黄色葡萄球菌、大肠杆菌和白色念球菌)并延长橙汁储存的货架期,而且等离子体对橙汁营养及理化性质的影响不大。pH值在等离子体菌类灭活中不起主要作用,分析后认为等离子体中的带电粒子和氧自由基(ROS)才可能是导致菌类灭活的主要因素。

Effect of Dielectric Barrier Discharge on Microorganism Inactivation and Quality of Orange Juice

In order to eliminate some unwanted side-effects caused by thermal processes sterilization,non-thermal sterilization techniques have been rapidly developed in recent years.The low temperature plasma(LTP) generated by parallel-plate electrode DBD was employed to sterilize three kinds of microorganisms inoculated with and without orange juice,and its influence on quality of orange juice was investigated.Three kinds of typical microorganisms,Staphylococcus aureus(gram-positive),Escherichia coli(gram-negative),and Candida albicans(typical of fungi),were employed to explore the inactivation mechanisms.The effect of LTP on microorganism inactivation with different treatment time was investigated.In addition,the effect of LTP on shelf life of orange juice was studied,and the biological and medical detection methods and instruments(4-dinitrophenylhydrazine colorimetry,sodium hydroxide titration,Abbe refractometer,acidometer and spectrophotometer) were employed to measure the Vit C concentration,total acid,°Brix,pH value and turbidity in orange juice before and after plasma treatment,also the effect of pH value on microorganism inactivation was investigated.The experimental results show that: low temperature plasma is safe and effective in inactivating microorganisms(Staphylococcus aureus,Escherichia coli,and Candida albicans) in orange juice,and can significantly extend its shelf life.LTP treatment has hardly effect on nutritional,physical and chemical characteristics of the orange juice.The pH value does not play an important role in microorganism inactivation.It is proposed that microorganism inactivation is mainly due to reactive oxygen species(ROS) and charged particles.