Application of pulsed electric fields for cell disintegration
- How does it work?
- What can it be used for?
- What can it not be used for?
- Related Facilities
- Further Information
|Key words||Cell rupture, pulsed electric fields, cell disintegration, extraction, mass transfer, cell permeabilisation, PEF, pre-treatment, stress reaction, drying|
How does it work?
|Primary objective||Stabilization, improvement of extraction yield (e.g. juice yield or oil yield) and mass transfer|
|Working principle|| The application of pulsed electric fields leads to permeabilisation of biological cell membranes.
Exposing intact cell membranes to an external electric field causes a charging of the cell membrane resulting in a polarization. An increasing electric field strength effects a higher electric potential in the cell membrane up to a critical value. When the critical electrical potential is induced by the pulses, a rapid electrical breakdown of the cell membrane occurs and pore formation starts. The pore formation can be reversible or irreversible, depending on the treatment time and the electric field strength.
Figure 1: Microbiological inactivation in dependency to the applied electric field; E electric field applied to the cell; EC critical electric field intensity (1)
The permeability of the cell membrane is related to the conductivity. A change in the permeability results in a change in the conductivity. Conductivity measurement makes it possible to determine the extent of the total or local disintegration of the cell membrane. (2)
The permeabilisation of the cell membrane offers the possibility to increase the extraction yield or to induce stress reactions in the cell. Because of the permeabilisation, the content of the cells can go out and in comparison to other disintegration methods (thermal or physical ones) extraction yield is higher. (3, 5, 6,7,8)
To achieve permeabilisation, an electric field strength of 0.5 – 1 kV/cm and a treatment time of 100-10.000 µs or a higher electric field strength of 1-10 kV/cm and a lower treatment time of 5-100 µs is used. (4)
The effectiveness of the PEF treatment and also the electric field strength is cell specific. It depends on the location of the metabolites within the cell and also on the structure of the cell membrane. A cell with a secondary cell wall requires higher electric field strength to achieve permeabilisation.
|Additional effects|| Cutting force reduction and improvement of cut quality due to tissue softening
Enhancement of pressing, diffusion, drying, dehydration of the plant/meat product Reduced processing time Release of enzymes Low thermal effects
|Important process parameters|| electric field strength, specific energy, treatment time
Other process parameters are the pulse shape (square wave pulses are most effective) and configuration of the treatment chamber (co-linear configuration is the most common design of the treatment chamber)
|Important product parameters||type of cells/tissue|
What can it be used for?
|Products|| Animal and plant cells
Vegetables and fruits (e.g. grapes, carrots, potatoes, apples, sugar beets) Raw material for oil production (e.g. maize, rose petals, soybeans)
|Operations||Separation, structure forming, conversion|
|Solutions for short comings||Extraction at mild conditions to protect e.g. heat sensitive products, induction of stress reactions to activate the production of secondary metabolites, improvement of mass transfer for separations processes, shorter drying times, enhancement of nutritional ingredient content|
What can it NOT be used for?
|Products||Applicable to aqueous and pumpable systems (pipe system) and to solid products (belt system)|
|Operations||Microbial inactivation, the application of PEF can be used as a pre-treatment (using low treatment conditions (electric field strength (1-3 kV/cm) and specific energy input (5-20 kJ/kg))|
|Other limitations||Considerable investment and maintenance costs|
|Risks or hazards||Structural deformation and change of textural properties may be undesired|
|Maturity||A batch and continuous system is commercially available, continuous system is available up to capacities of 50.000 l/h|
|Modularity /Implementation|| Continuous belt and pipe system can be easily implemented into existing lines.
Processing in a range of seconds, in contrast to chemical or thermal treatments
|Consumer aspects||Consumers perceive the technique as environmental friendly and are positive to the naturalness of the product|
|Legal aspects|| EU: According to available scientific paper, which describe no change of the product due to the PEF treatment: no novel food approval required
No declaration or labeling required US: FDA letter of no objection (1996)
|Environmental aspects||Energy efficient, waste free technique|
Facilities that might be interesting for you
|Institutes||DIL, TU Berlin, Karlsruhe Institute of Technology, University of Zaragoza, University College Dublin, University of Technology of Compiègne, Lund University, University of Salerno, Washington State University, McGill Uni DFSAC, Jilin University|
|Companies||DIL Technologie GmbH, Diversified Technologies, ScandiNova, KEA-Tec|
|References|| 1.) Barbosa-Cánovas, G.V., M. M. Góngora-Nieto, U. R. Pothakamury, and B. G. Swanson. “Fundamentals of High-Intensity Pulsed Electric Fields.” Preservation of Foods with Pulsed Electric Fields. San Diego: Academic Press, 1999. 1-19
2.) Angersbach, A., V. Heinz and D. Knorr (2000). Effects of pulsed electric fields on cell membranes in real food systems. Innovative Food Science & Emerging Technologies Vol.1, No.2, pp. 135-149
3.) Knorr, Dietrich, Alexander Angersbach, Mohamed N. Eshtiaghi, Volker Heinz, and Dong-Un Lee. "Processing concepts based on high intensity electric field pulses." Trends in Food Science & Technology 12.3-4 (2001): 129-35.
4.) Schilling, Susanne, Thorsten Alber, Stefan Toepfl, Sybille Neidhart, Dietrich Knorr, Andreas Schieber, and Reinhold Carle. "Effects of pulsed electric field treatment of apple mash on juice yield and quality attributes of apple juices." Innovative Food Science & Emerging Technologies 8.1 (2007): 127-34.
5.) Bazhal, Maksym, Nikolai Lebovka, and Eugene Vorobiev. "Optimisation of Pulsed Electric Field Strength for Electroplasmolysis of Vegetable Tissues." Biosystems Engineering 86.3 (2003): 339-45.
6.) Coster, H. G. L. "A Quantitative Analysis of the Voltage-Current Relationships of Fixed Charge Membranes and the Associated Property of "Punch-Through"." Biophysical Journal 5.5 (1965): 669-86.
7.) Grimi, Nabil, Fatine Mamouni, Nikolaï Lebovka, Eugène Vorobiev, and Jean Vaxelaire. "Impact of apple processing modes on extracted juice quality: Pressing assisted by pulsed electric fields." Journal of Food Engineering 103.1 (2011): 52-61.
8.) Puértolas, E., N. López, S. Condón, I. Álvarez, and J. Raso. "Potential applications of PEF to improve red wine quality." Trends in Food Science & Technology 21 (2010) 247–255.
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