Pulsed Electric Field Processing
Raghupathy Ramaswamy, Tony Jin, VM (Bala) Balasubramaniam and Howard Zhang
What is Pulsed Electric Field Processing?
Pulsed electric field (PEF) processing is a non-thermal method of food preservation that uses short bursts of electricity for microbial inactivation and causes minimal or no detrimental effect on food quality attributes. PEF can be used for processing liquid and semi-liquid food products.
How Does This Technology Benefit Consumers?PEF processing offers high quality fresh-like liquid foods with excellent flavor, nutritional value, and shelf-life. Since it preserves foods without using heat, foods treated this way retain their fresh aroma, taste, and appearance.
How Does PEF Work?PEF processing involves treating foods placed between electrodes by high voltage pulses in the order of 20–80 kV (usually for a couple of microseconds). The applied high voltage results in an electric field that causes microbial inactivation. The electric field may be applied in the form of exponentially decaying, square wave, bipolar, or oscillatory pulses and at ambient, sub-ambient, or slightly above-ambient temperature. After the treatment, the food is packaged aseptically and stored under refrigeration.
How Does PEF Inactivate Microorganisms?
PEF treatment has lethal effects on various vegetative bacteria, mold, and yeast. Efficacy of spore inactivation by PEF in combination with heat or other hurdles is a subject of current research. A series of short, high-voltage pulses breaks the cell membranes of vegetative microorganisms in liquid media by expanding existing pores (electroporation)
What Types of Foods Benefit From PEF Treatment?
Application of PEF technology has been successfully demonstrated for the pasteurisation of foods such as juices, milk, yogurt, soups, and liquid eggs. Application of PEF processing is restricted to food products with no air bubbles and with low electrical conductivity. The maximum particle size in the liquid must be smaller than the gap of the
What is the Shelf-life of a PEF Processed Product?
In general, the shelf-life of PEF-treated and thermally pasteurised foods is comparable. PEF pasteurisation kills microorganisms and inactivates some enzymes and, unless
How are PEF Processed Foods Stored?
PEF pasteurised products currently are stored refrigerated. In some cases (for example, milk), this is necessary for safety (to prevent the growth of spores in low-acid
Is Commercial Scale Equipment Available?
Yes. In the United States, the first commercial scale continuous PEF system is installed at The Ohio State University’s Department of Food Science and Technology. This PEF system is part of a new food treatment system assembled by a Department of Defence (DoD) sponsored, University directed industry consortium. Diversified Technologies Inc., Bedford, MA, builds commercial PEF systems of processing volumes ranging from 500 to 2,000 L/h, with The Ohio State University supplying the PEF treatment chambers.
Is PEF Equipment Safe for the Environment?
Yes. This process uses ordinary electricity. The facility meets electrical safety standards and no harmful environmental by-products are produced.
What is an Integrated Continuous PEF Processing System?
An integrated PEF system consists of a fluid handling unit, high voltage pulse generator, PEF treatment chambers, and packaging machine. The fluid handling unit delivers
What is a PEF Treatment Chamber?A PEF treatment chamber consists of at least two electrodes and insulation that forms a volume, i.e. PEF treatment zone, where the foods receive pulses. The electrodes are made of inert materials, such as titanium.
How Economical is PEF Processing?PEF is an energy efficient process compared to thermal pasteurisation. The PEF processing would add only $US 0.03–$0.07/L to final food costs. A commercial-scale PEF system can process between 1,000 and 5,000 L of liquid foods per hour and this equipment is scalable. Generation of high voltage pulses having sufficient peak power (typically megawatts) is the limitation in processing large quantities of fluid economically. The emergence of solid-state pulsed power systems, which can be arbitrarily sized by combining switch modules in series and parallel, removes this limitation.
What Regulatory Approval is Required for Commercialising a PEF Processed Product?
Currently, regulatory requirements are evolving, but will likely involve the development of Hazard Analysis Critical Control Point (HACCP) plans for most juices and beverages. A current USDA project will address these very points.
OSU Extension embraces human diversity and is committed to ensuring that all educational programs conducted by Ohio State University Extension are available to
Are Facilities Available for Product Development Before Venturing into PEF Processing?
An industrial scale-up PEF pilot plant facility is available at The Ohio State University in the Department of Food Science and Technology. Food processors are invited to take advantage of the expertise of OSU faculty and staff, and facilities to conduct confidential product evaluations for food safety, quality, and shelf-life, and to obtain guidance
Reference to commercial product or trade names is made with the understanding that no
Raghupathy Ramaswamy is a Graduate Research Associate (e-mail: email@example.com), Dr Tony Jin is PEF Pilot Plant Manager (e-mail: firstname.lastname@example.org), Dr VM (Bala) Balasubramaniam is an Assistant Professor, Food Safety Engineering (e-mail: email@example.com), and Dr Howard Zhang is Adjunct Professor, Food Engineering and Research Leader, USDA ERRC, Department of Food Science and Technology, Ohio State University, Columbus, OH 43210-1007, USA; e-mail: firstname.lastname@example.org).
Permission to reproduce this Fact Sheet, originally published as Appendix 2 in Nonthermal Processing Technologies for Food (Zhang, HQ, Barbosa-Canovas, GV, Balasubramaniam, VM, Dunne, CP, Farkas, DF and Yuan, JTC, eds, Blackwell Publishers Ltd and the Institute of Food Technologists, 2011, ISBN: 978-0-8138-1665-5), is gratefully acknowledged.