What is PEF (pulsed electric field)?

 

Pulsed Electric Field (PEF) treatment is a non-thermal processing technology that involves the application of short, high-voltage pulses substance (biomass), typically a liquid or semi-solid material leading to the destabilization of the cell membrane and or enhanced permeabilization. In this post, you’ll learn more about how it works.

 

The discovery and development of Pulsed Electric Field (PEF technology can be attributed to several key observations and advancements in the field of electrical engineering and biology.

Through a combination of electrical engineering principles, biological studies, and practical experimentation, the discovery of PEF technology emerged as a means of utilizing PEF to preserve food and achieve other desired effects.

Read more about this here -> “History of PEF”

How does PEF technology work?

Every cell (membrane) contains +/- ions. By adding electric power between two electrodes, an electric field is created on the +charge which hence repels and pulls the + and – ions respectively. This, therefore, adds to increase membrane permeability or cell lysis. 

Food products, such as vegetable oils, juices, dairy products, and more – are capable of transferring electricity because of the presence of ions, giving the product in question a certain degree of electrical conductivity. So, when an electrical field is applied, electrical current flows into the commodity and is transferred to each point in the liquid because of the charged molecules present.  

This leads to the cell breaking or leaves it entirely destroyed depending on the power of the electricity. PEF technology has been presented as advantageous in comparison to, for instance, heat treatments, because it is considered as being non-thermal, it deactivates microorganisms while maintaining the original color, flavor, texture, and nutritional value of the unprocessed food. PEF is hence more energy efficient which can contribute to a more sustainable food system.

Pulsed Electric Field applied on plant cell
Plant cell
Magnified cell membrane contains charged particles

What happens when PEF is applied to a substrate?

PEF technology is primarily used in food processing and preservation. When applied to foods or beverages, the electric pulses create temporary pores or holes in the cell membranes of microorganisms, such as bacteria and yeasts, present in the substance. This disruption of the cell membranes can lead to the inactivation or destruction of the microorganisms, thereby extending the shelf life of the product and reducing the need for traditional thermal processing methods like pasteurization. 

Further Reading –> Food products suitable for PEF treatment

  1. Electroporation: One of the primary effects of PEF is electroporation. Electroporation refers to the temporary formation of pores or channels in the cell membranes of biological cells within the substrate. These pores allow for the passage of ions, molecules, and particles that would not normally cross the cell membrane. Electroporation occurs due to the high electric field strength applied during PEF.

  2. Permeabilization: Electroporation and permeabilization are often (or can be) used interchangeably. The electroporation of cell membranes leads to increased permeability, allowing substances present in the surrounding environment (e.g., solutes, ions, compounds) to enter the cells more easily. This enhanced permeabilization can have various applications, such as facilitating the extraction of intracellular compounds or aiding in the uptake of desired molecules.

  3. Microbial Inactivation: PEF can cause damage to microorganisms present in the substrate. The high-intensity electric field disrupts the cell membranes of bacteria, yeasts, molds, and other microorganisms. This damage can lead to cell death or inactivation, rendering the microorganisms unable to grow, reproduce, or cause spoilage. PEF is particularly effective against microorganisms due to their smaller size and higher susceptibility to electric fields compared to larger cells or tissues.

  4. Enzyme Activation or Inactivation: PEF can affect enzymatic activity within the substrate. Depending on the specific enzymes and their sensitivity to the electric field, PEF can either activate or inactivate certain enzymes. This effect can be advantageous in food processing, as it can help preserve the quality, flavor, and nutritional value of the treated product.

  5. Structural Changes: PEF can induce structural changes in the substrate, primarily due to the effects on cellular components. For example, the disruption of cell membranes can lead to changes in the texture, viscosity, or stability of the substrate. These changes can impact the overall quality and properties of the treated material.

How PEF technology is implemented in food processing systems

The OptiCept PEF application includes a treatment chamber. As the substrate passes through the chamber it is subjected to the electric pulses.

The effects of PEF are highly dependent on the specific parameters used, such as voltage, pulse duration, frequency, and treatment time. The optimization of these parameters is crucial to achieving the desired effects on the substrate.

OptiCepts patented CEPT® technology is an innovative type of PEF. The CEPT® platform is a high-voltage generator combined with treatment chambers. A method to create, control, and apply pulses more efficiently. It holds several advantages compared to traditional pulsed electric field technology. 

Through different settings, CEPT® can change e-field, pulse width, frequency (PPV), and strength after the requested treatment. CEPT® applications can be ran both in bipolar and monopolar modes. (Cleaning and wear of the electrodes are done more easily.)  

The flow is automatically adjusted, which means it consistently achieves an effective treatment and always uses the same energy density (KJ/kg) for the substrate, independent of the conductivity.

This enables us to provide a PEF system that can be applied to a wide range of commodities.  Including juice, olive oil, wine, dried commodities, and much more.

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