Background

Ohmic heating (OH) is a novel method of heating various food materials efficiently, instantly and volumetrically. The quick and volumetric heating during OH results in efficient enzyme and microbial inactivation. Thus, OH can be used as an efficient alternative to the conventional thermal processing method.

Scope and approach

OH has been applied to various food materials, which include fruits and vegetable products, milk, meat, seafood etc. Inactivation of quality degrading enzymes and spoilage causing microbes to a desired safe level is the prime objective of thermal processing of food, which can be easily achieved by OH process. In addition to the thermal effects, OH also has some non-thermal effects on microbial and enzyme activities due to the presence of electric current during heating. However, these non-thermal effects of OH are possible only in enzymes containing prosthetic metallic groups such as, Cu in PPO, Fe in lipoxygenase, Zn and Mg in alkaline phosphatase.

Key findings and conclusions

Various models such as First order, Bi-phasic and Lumry–Eyring mechanism have been reported in literature for the enzyme inactivation by OH. Enzyme inactivation has been found to increase with increasing electric field strength (V/cm) during the OH process. The spoilage causing microorganisms can also be inactivated efficiently by OH as compared to conventional heating. Higher voltage gradients enhance the non-thermal effects of OH on microbial reduction by resulting in the higher electroporation. The frequency of the electric current also plays an important role in microbial reduction. Various components present in food such as fat, sugar and acid content affect the electrochemical properties of food material, thus affect the performance of OH in reducing the microbial load.

中文翻译：

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欧姆加热辅助灭活食品中酶和微生物的研究进展

背景

欧姆加热（OH）是一种高效，即时和定量加热各种食品原料的新颖方法。OH期间快速且定量的加热导致有效的酶和微生物失活。因此，OH可以用作常规热处理方法的有效替代品。

范围和方法

OH已应用于多种食品原料，包括水果和蔬菜产品，牛奶，肉类，海鲜等。使质量降解酶失活和使微生物变质至所需安全水平的腐败是食品热处理的主要目标，通过OH工艺很容易实现。除热作用外，由于加热过程中电流的存在，OH对微生物和酶的活性也有一些非热作用。但是，只有在含有人工金属基团的酶（如PPO中的Cu，脂氧合酶中的Fe，碱性磷酸酶中的Zn和Mg）中，OH的这些非热作用才可能发生。

主要发现和结论

文献报道了多种模型，例如一阶，双相和Lumry-Eyring机制，可通过OH进行酶灭活。已发现，在OH过程中，酶灭活会随着电场强度（V / cm）的增加而增加。与常规加热相比，还可以通过OH有效地使引起腐败的微生物失活。更高的电压梯度会导致更高的电穿孔，从而提高OH对微生物还原的非热效应。电流的频率在微生物减少中也起重要作用。食物中存在的各种成分（例如脂肪，糖和酸含量）会影响食物材料的电化学性能，从而影响OH在降低微生物负荷方面的性能。