Background

The elimination of microbial cells is one of the most critical steps in food processing. Conventional heating is the application of diffusive and convective heat mechanisms and is traditionally applied to assure food safety. However, such process is also harmful to others thermosensitive compounds, compromising desirable sensorial characteristics. The large temperature gradients caused by conventional heating result in lower thermal efficiency, overheated zones and high processing times. To overcome these limitations, emergent technologies have been studied in the past years, such as ohmic heating.

Scope and approach

The aim of this review was to analyze the state of the art of microbial inactivation by ohmic heating. This study emphasizes comparisons of ohmic and conventional heating, as well as comparisons of ohmic heating in several distinct scenarios (such as variations in the frequency and electric field).

Key findings and conclusions

The literature analysis shows that the most analyzed microbial species was Escherichia coli and studies dealing with fungi were less numerous comparing with studies dealing with bacteria. Concerning the lethality of conventional and ohmic heating, authors have shown that ohmic treated foods had smaller D values in various temperatures. The effect of frequency lacks of experimental data to explain the real impact of this parameter in the inactivation rate, once different authors have found divergent results. Moreover, increases in the electric field and salt content and decreases in the pH, fat and solid content have demonstrated higher heating rates and, therefore, higher inactivation rates.

中文翻译：

---

欧姆加热使微生物失活：文献综述和不同工艺变量的影响

背景

消除微生物细胞是食品加工中最关键的步骤之一。常规加热是扩散和对流加热机制的应用，传统上是为了确保食品安全而应用的。但是，这种方法也对其他热敏化合物有害，损害了所需的感官特性。传统加热导致的大温度梯度导致较低的热效率，过热区域和较长的处理时间。为了克服这些局限性，近年来研究了新兴技术，例如欧姆加热。

范围和方法

这篇综述的目的是分析通过欧姆加热使微生物失活的技术现状。这项研究强调了欧姆加热和常规加热的比较，以及在几种不同情况下（例如频率和电场的变化）的欧姆加热的比较。

主要发现和结论

文献分析表明，分析最多的微生物是大肠杆菌，与真菌研究相比，真菌研究较少。关于常规加热和欧姆加热的致死性，作者表明，在各种温度下，经过欧姆处理的食品的D值较小。频率的影响缺乏实验数据来解释该参数对失活率的实际影响，一旦不同的作者发现了不同的结果。此外，电场和盐含量的增加以及pH，脂肪和固体含量的降低已证明具有较高的加热速率，因此具有较高的失活速率。