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脉冲电场(Pulsed Electric Field,PEF)杀菌是将脉冲电压施加到处理室的两极,产生电场对食品物料进行杀菌的过程,在整个过程中,处理室中的电场强度与温度分布是影响系统杀菌效果以及食品质量的两个关键因素。作者在建立同场处理室的三维模型的基础上,根据电场、流场、温度场理论,建立了脉冲电场杀菌系统三场耦合的数学模型,模拟在脉冲电压V、脉宽τ、频率f、流速υ和温度T等条件下,NaCl溶液的流体特性、温度分布以及处理室中的电场分布,得出了同场处理室几何尺寸与温度和电场分布的关系,为优化处理室结构,改善杀菌效果提供重要依据。 相似文献
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高压脉冲电场(pulsed electric fields,PEF)杀菌技术是当今备受关注的非热杀菌技术之一。处理室作为高压脉冲电场的重要组成单元,其主要功能是利用强电场力作用,在食品物料通过处理室时,使其中微生物的细胞结构在极短时间内遭到破坏,菌体死亡,从而达到杀菌效果。处理室中电场强度和温度分布是影响系统杀菌效果和食品质量的主要因素,通过对处理室内流体动力学与电场和温度场的耦合数值模拟对其进行有效解析。数值模拟的主要目的是优化处理室的几何结构,进而改善电场强度和温度分布的均匀性,从而避免局部食品物料的过处理、欠处理以及介质击穿等现象。文章总结数值模拟方法在高压脉冲电场性能研究中的应用,重点分析说明数值模拟方法在处理室内流体动力学、电场强度和温度场等方面的研究,并对该方法在高压脉冲电场应用中的进一步研究进行展望。 相似文献
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高压脉冲电场杀菌技术是一种新型的高效非热杀菌技术。高压脉冲电场处理室是杀菌处理的关键部件,其结构形式决定了处理室内部电场分布、温度场分布、流场分布,并影响杀菌处理的效果,同时电场强度和温度分布影响被处理食品的口味。以不同结构共场杀菌处理室为研究对象,利用COMSOL Multiphysics软件对共场杀菌处理室内部电场分布、温度场分布、流场分布对处理参数均匀性的影响进行了仿真。仿真结果表明,绝缘体无内嵌的处理室电场强度分布不均匀,对绝缘体倒椭圆角后的处理室可有效改善电场及流场分布,进而有效降低局部温升,改善处理效果。 相似文献
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高压脉冲电场(PEF)用于食品杀菌具有时间短、能耗低、能有效保存食品营养成分和天然色、香、味特征,非常具有工业化前途。本文是高压脉冲电场(PEF)在食品杀菌中的实践及它在工业生产加工中的应用。鲜紫菜加工厂应用PFE杀菌的技术工艺过程,设备的选型,参数设计。以往高压脉冲电场(PEF)技术多数停留在实验研究阶段,实际生产中的应用不多,此项目是对高压脉冲电场(PEF)杀菌技术的集成实施,从生产反馈中获得优化数据,有较好的推广前景。 相似文献
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不同杀菌方法对蛋清物化性质的影响 总被引:1,自引:0,他引:1
本研究以蛋清液为基质,接种大肠杆菌、沙门氏菌和金黄色葡萄球菌后,比较了高密度CO2(DPCD)、高压脉冲电场(PEF)及热处理对这三种菌的杀灭效果以及对蛋清液物化性质的影响,结果表明:对于大肠杆菌和沙门氏菌,DPCD的杀菌效果最佳;热处理杀灭三种细菌达到2~3个对数值,效果优于PEF处理;未处理蛋清液货架期为2d左右,而经过DPCD、PEF和热处理杀菌后,可分别延长蛋清液的货架期至20、12、14d。DPCD、PEF和热处理也使得蛋清液的物化性质发生一定程度的变化。DPCD处理显著降低了蛋清液的pH及凝胶强度,并且使其电导率大大增加;PEF处理提高了蛋清液的黏度,降低了其凝胶强度,而热处理对其物化性质影响最大,降低了蛋清液的黏度,显著提高了其凝胶强度。 相似文献
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杀菌处理腔是高压脉冲电场(Pulsed Electric Field,PEF)处理系统的重要组成部分,为了开发出适合于多个处理腔串联组合使用的处理腔单元,对椭圆内嵌型共场式杀菌处理腔进行了建模,并利用ANSYS软件得到处理腔内的电场分布和流体动力学特性,然后在仿真分析的基础上,对处理腔结构进行了优化,提出了一种基于流体特性优化的新型共场式杀菌处理腔结构,经验证该处理腔的性能可以满足多处理腔单元串联组合使用的要求,为进一步优化高压脉冲电场杀菌处理腔提供了新思路。 相似文献
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为深入研究脉冲电场的灭菌机理,探讨电场与细胞膜的作用机制,利用拉曼光谱谱图分析了不同电场场强下磷脂脂质体构象的变化。结果表明,拉曼峰值比I1085/I1064随着电场场强的增加而相应增大,而I1085/I1123随着电场场强的增加而先增加后减少,但比值仍高于空白样,说明经过电场处理后,脂质体C-C扭曲构象的数目增多;而I2885/I2850随着场强的增加呈现递减的趋势。由此可以说明经电场处理后的脂质体磷脂分子间烃链的无序度增加,导致细胞膜流动性增强。 相似文献
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为探究高压脉冲电场(PEF)对酿酒酵母的灭菌机理,研究了从亚细胞水平揭示PEF处理下的损伤亚致死酵母细胞的存在及产生规律。采用pH7.2的磷酸盐缓冲液(PBS)模拟体系,30 kV/cm电场强度下循环处理100~500μs,通过选择性培养基与非选择性培养基菌落计数对PEF处理前后亚致死酵母细胞进行了研究。结果显示,亚致死酵母的临界渗透压为4%NaCl,PEF处理后,酿酒酵母的亚致死率可达到4.5个对数,亚致死细胞数量达到1.5个对数,且亚致死程度随处理时间的延长而加大。选择性培养基可用于PEF处理过程中亚致死细胞的定量检测。 相似文献
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《Innovative Food Science and Emerging Technologies》2007,8(2):205-212
A pulsed electric field (PEF) system was designed and constructed using modern IGBT technology. The main focus of this work was to design a new PEF treatment chamber that operate at high electric field intensities with limited increase in liquid temperature and limited fouling of electrodes. Four multi-pass treatment chambers were designed consisting of two stainless steel mesh electrodes in each chamber, with the treated fluid flowing through the openings of the mesh electrodes. The two electrodes are electrically isolated from each other by an insulator element designed to form a small orifice where most of the electric field is concentrated. Dielectric breakdown inside the chambers was prevented by removing the electrodes far from the narrow gap. The effect of PEF treatment on the inactivation of gram-negative Escherichia coli ATCC 25922 suspended in simulated milk ultra-filtrate (SMUF) of 100%, 66.67% and 50% w/w was investigated. Treatments with the same electrical input power but with higher electric field strengths provided larger degree of killing. The effect of PEF treatment using suspensions at different flow rates and different pulse frequencies was also investigated. In general, the inactivation rate of E. coli increased with increasing electric field strength, treatment time and processing temperature. More than 6 log reductions in E. coli suspended in SMUF was achieved using electric field intensity in the range of (37.2–49.6 kV/cm) with a treatment temperature not exceeding 38 °C.Industrial relevanceThis paper presents an innovative pulsed electric field system for non-thermal pasteurisation of liquid food. The system design provides uniform distribution of electric field and minimum fouling of electrodes. This PEF system can be scaled up to any industrial size, making it attractive for industrial applications. 相似文献
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Roman Buckow Pascal BaumannStefanie Schroeder Kai Knoerzer 《Journal of food engineering》2011,105(3):545-556
Approximations of the electric field strength and specific energy input of continuous pulsed electric field (PEF) systems often assume parallel plate configurations. However, it is known that actual electric field strengths and specific energy inputs can be significantly different from this simplistic approach. A systematic study of more than 150 dimensions and various insulator geometries of pilot-scale PEF treatment chambers with co-linear electrode configuration was performed. A reduction of the inner diameter of the insulator and its shape changes the distribution and (average) intensity of the electric field. Both, the average electric field strength of the PEF treatment zone and the actual specific energy input, were significantly lower than the expected values derived from dividing the applied voltage by the electrode gap. The difference between theoretical and actual values generally increased with increasing electrode radius and decreasing electrode gap. The relative ratios of theoretical electric field strength or specific energy input to actual (average) electric field strength or specific energy input showed a linear dependency on the ratio of electrode radius and gap. The determined relationships of specific energy input and treatment chamber dimensions and geometry were experimentally validated in four different PEF treatment chambers. 相似文献