How it works
PEF: how it works
Pulsed electric field processing is an efficient non-thermal food processing technique using short, high voltage pulses. These pulses induce poration of plant, animal and microbial cells, leading to cell disintegration and microbial inactivation. For microbial inactivation a higher treatment intensity is required than for cell disintegration only.
Pulsed electric field technology
Pulsed electric field technology involves the application of microsecond high voltage pulses in the order of 10 to 60 kV. The high voltage pulses applied induce pores in cell membranes, causing a loss of barrier function, leakage of intracellular content and loss of vitality.
The treatment is applied continuously in a chamber – a setup of multiple electrodes. For microbial inactivation of liquids and semi viscous liquids the pulse generator is combined with a PEF treatment chamber. While being pumped (liquids and semi viscous liquids) or transported (solids) through the treatment chamber, the product is exposed to the high voltage pulses. The required treatment time is less than a second. The pulses are applied at repetition rates of up to a maximum of 500 pulses per second to allow sufficient treatment of all volume elements. Besides electrical parameters such as field strength and specific energy input, product temperature and product recipe also have an impact on treatment intensity.
Pulsemaster Conditioner
As a continuous process with low space requirements pulsed electric field equipment can easily be implemented in existing lines. Pulsemaster’s Conditioner is a technical improved PEF concept and more energy efficient than the previous generation. The new equipment gives a better pulse treatment of the product with a more compact and modular pulse generator. For cell disintegration of solids the pulse generator is combined with a robust and hygienic transport system and PEF treatment chamber.
Proven track record
The pulse generators have a proven track record for food industry and research applications. All PEF systems used by industry to make French fries and crisps, built according to Marx solid-state typology and running succesfully in potato industry in Germany, US, Canada, The Netherlands, Belgium, Austria, Australia, India and China, technically originate from the work of Pulsemaster’s highly qualified team of German engineering experts. Our robust Marx solid-state typology enables better pulse control and high reliability. Pulsemaster can supply a range of robust PEF systems, covering a wide power range up to 100kW per system. The design of Pulsemaster PEF systems are suitable for any regional installation and control system requirements and adhere to all regional certification requirements. Each Pulsemaster PEF system is built with the highest quality German and Dutch engineering to withstand continuous operation (24/24) in industry.
Puncturing the cell membrane
Cell cytoplasm is surrounded by a thin semi-permeable layer, the cell membrane. The membrane acts as a semi-permeable barrier for the intra- and extracellular transport of ions and macromolecules. This membrane is a phospholipid bilayer with a thickness of 5 nanometer (nm). By exposing the cell to a pulsed electrical field the cell membrane becomes punctured. The membrane is punctured with small pores of 50-100 nanometer each. This effect is called electroporation, which is the loss of the cell’s barrier function allowing access to the cell’s valuable contents.
Electroporation takes places after 1 microsecond (µs). The process is quick, flexible, energy-efficient and because heat is minimized, products have a longer shelf life whilst maintaining better nutritional value than with traditional food processing techniques.
Pulsed Electric Field (PEF) or electroporation works by puncturing the cell membrane, whatever the size of cell. The process is targeted, gentle and clean. As a result, we measure dramatic increases in yield, the preservation of pigments, antioxidants and vitamins. PEF makes healthy products last longer.
A cell dimension can be 20-100 micrometer (µm), a bacteria dimension 2-10 micrometer (µm). Pores can have a size of 50-100 nanometer (nm) each. These small pores will be more stable when the cell membrane is subjected to more pulses. Pulsmaster’s Conditioner can run up to max 500 pulses per sec (pulse repetition rate of max 500 Hz).
Loss of cell membrane barrier function causes microbial death. Despite its targeted effect on cell membranes PEF does not affect vitamins, flavors or proteins. This allows microbial decontamination of heat sensitive liquids whilst retaining their sensory qualities and functional value.
Membrane disruption occurs when the induced membrane potential exceeds a critical value of 1 volt in many cellular systems, which corresponds to an external electric field of about 10 kV/cm in the case of E. coli. In case of killing E. coli and reducing the microbial load of a liquid you need a threshold value of about 10 kV/cm. Electroporation is irreversible above a certain threshold.
Targeted process
Pulsed Electric Field (PEF) processing or electroporation works by puncturing the cell membrane, whatever the size of cell. The process is targeted, gentle and clean. As a result, we measure dramatic increases in yield and the preservation of pigments, antioxidants and vitamins. PEF makes healthy products last longer.
A cell dimension can be 20-100 micrometer (µm), a bacteria dimension 2-10 micrometer (µm). Pores can have a size of 50-100 nanometer (nm) each. These small pores will be more stable pores when the cell membrane is subjected to more pulses. Pulsmaster’s Conditioner can run up to max 500 pulses per sec (a pulse repetition rate of maximum 500Hz).
Loss of cell membrane barrier function causes microbial death. Despite its targeted effect on cell membranes PEF does not affect vitamins, flavors or proteins. This allows microbial decontamination of heat sensitive liquids whilst retaining their sensory qualities and functional value.
Membrane disruption occurs when the induced membrane potential exceeds a critical value of 1 V in many cellular systems, which corresponds to an external electric field of about 10 kV/cm in the case of E. coli. In case of killing E. coli and reducing the microbial load of a liquid you need a minimum threshold value of about 10 kV/cm. Electroporation is irreversible above a certain threshold.
Influence of the food matrix
The dielectric strength of the food matrix has a significant influence on the applicability of PEF, as dielectric breakdown has to be prevented. Air bubbles cannot withstand high electric field strengths. They may be present in sparkling products or be released due to temperature increase. In particular for microbial inactivation, where a higher electric field strength is required, air has to be removed from the product. Vacuum degassing or pressurizing the treatment media during PEF processing, using positive back pressure, can minimize the presence of air bubbles.
For treatment of solid foods, such as plant or animal material or fruit mashes, air encapsulations have to be removed to avoid electric discharges. Foam forming products might be unsuitable for PEF-treatment.