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首页> 外文学位 >Mechanisms of inactivation and microbial inactivation kinetics in the Pulsed Light treatment of foods.
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Mechanisms of inactivation and microbial inactivation kinetics in the Pulsed Light treatment of foods.

机译：食品脉冲光处理中失活和微生物失活动力学的机制。

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摘要

Pulsed Light technology utilizes high powered pulses of broad spectrum light to reduce microorganisms on food and food contact surfaces. While previous research has shown Pulsed Light to be effective at reducing various microorganisms on a variety of substrates, a better understanding of inactivation kinetics, pairing Pulsed Light with other antimicrobial treatments, and the cellular effect of Pulsed Light treatment will provide better insight into potential opportunities for future use of this technology. Inactivation of Listeria innocua in liquid suspensions and on the surface of stainless steel showed pronounced tailing. The utilization of the Weibull model accurately predicted inactivation in clear liquids but overestimated Pulsed Light's effectiveness on stainless steel surfaces where complex surface properties as well as inoculum size were of significant influence. The combination of Pulsed Light with the antimicrobial nisin was able to reach reductions of 4 to 5 log CFU/sausage of Listeria on the surface of sausages, extending storage from 8 day for individual treatments to 28 to 48 days suggesting that Pulsed Light in combination with additional antimicrobials can effectively reduce surface contamination of ready-to-eat foods. To evaluate the potential for repeated Pulsed Light exposure to lead to changes in growth and resistance behavior of survivors, L. monocytogenes, L. innocua , and E. coli were exposed to both low (1.1 J/cm 2) and high (10.1 J/cm2) levels of Pulsed Light and survivors were recovered and subsequently treated for 10 cycles of exposure and recovery. Isolates of all three organisms did not show changes in growth kinetics or resistance after multiple exposures when compared to untreated cells at either low or high fluence levels. Reduction levels of 3--4 and 5--6 log CFU/ml were obtained after exposure to 1.1 and 10.1 J/cm 2, respectively, for the untreated control and the repeatedly treated and recovered isolates. Whole genome microarray analysis showed increased transcription levels for stress related proteins, motility, and transcriptional regulators following both Pulsed Light and UV light. Removing the UV spectrum of Pulsed Light lead to no differences between treated and untreated samples and showed a downregulation in motility and cell membrane associated genes as well as no increases in stress response genes following exposure, suggesting that the mechanism of inactivation is related to the UV portion of Pulsed Light and the visible and NIR spectrum do not play a role in cell inactivation.
机译：脉冲光技术利用广谱光的高功率脉冲来减少食物和食物接触表面上的微生物。尽管先前的研究表明脉冲光可有效减少多种底物上的多种微生物，但更好地了解灭活动力学，将脉冲光与其他抗菌剂配对以及脉冲光处理的细胞作用将提供对潜在机会的更好洞察力供将来使用此技术。液体悬浮液和不锈钢表面的无毒李斯特菌灭活显示出明显的拖尾。 Weibull模型的使用可准确预测透明液体中的失活，但高估了脉冲光在不锈钢表面上的有效性，在这些表面上，复杂的表面特性和接种量会对影响很大。脉冲光与抗菌素乳链菌肽的结合能够使香肠表面的李斯特菌/香肠减少4至5 log CFU /香肠，从单个处理的8天延长到28至48天，这表明脉冲光与额外的抗菌剂可以有效减少即食食品的表面污染。为了评估重复脉冲光照射可能导致幸存者生长和抵抗行为发生变化的可能性，将单核细胞增生李斯特菌，无毒李斯特菌和大肠杆菌暴露于低（1.1 J / cm 2）和高（10.1 J回收脉冲光和幸存者的水平，然后进行10次暴露和恢复循环。与低或高通量水平下的未处理细胞相比，所有三种生物的分离物在多次暴露后均未显示出生长动力学或抗性变化。对于未经处理的对照以及经反复处理和回收的分离株，分别暴露于1.1和10.1 J / cm 2后，可获得3--4和5--6 log CFU / ml的降低水平。全基因组微阵列分析显示，在脉冲光和紫外线作用下，应激相关蛋白，运动性和转录调节因子的转录水平增加。去除脉冲光的紫外光谱不会导致处理后的样品与未处理的样品之间存在差异，并且显示出运动性和细胞膜相关基因的下调以及暴露后应激反应基因的增加，这表明灭活的机理与紫外线有关脉冲光的一部分以及可见光和近红外光谱在细胞失活中不起作用。

著录项

  • 作者

    Uesugi, Aaron Reid.;

  • 作者单位

    Cornell University.;

  • 授予单位 Cornell University.;
  • 学科 Agriculture Food Science and Technology.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 166 p.
  • 总页数 166
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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