FAQ about pulsed electric field processing

Pulsed electric field (PEF) 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.
PEF is instant, targeted, 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.
PEF improves the extraction rates of juices, sugars, coloring agents and other active substances and significantly extends shelf life. Diffusion processes, like water removal from plant or animal tissue or the absorption of marinades, spices and auxiliary substances are accelerated, thereby saving valuable time in production processes.

Yes, it is. PEF processing and electroporation are both used to describe the same technique. The pulsed electric field induces poration of cell membranes – that is where the word electroporation comes from. Permeabilization is another term used in this context.

The general aim is to create value by maximizing the effectiveness of natural raw materials. Electroporation generates significant increases in yield, freshness and flavor across a wide range of foods and applications.

PEF processing 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. 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 1000 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.

Depending on the aim of application, solid, semi-liquid and liquid foods can be treated.
Treatment of plant or animal tissue aiming on cell disintegration has practically no size limitations. It can be applied to whole fruits, vegetables and potato tubers, fruit or vegetable pieces and fruit or vegetable mashes, prior to separation processes. However, the maximum size of the plant or animal tissue must be smaller than the gap of the treatment chamber.
To achieve microbial inactivation, a higher treatment intensity is required, limiting the applicability to pumpable products with a particle diameter of less than 20 mm.

The dielectric strength of the food matrix has a significant influence on the applicability of PEF, as a 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.

Applications of PEF include mild preservation of beverages and semi-liquid food products, treatment of potatoes to replace thermal preheating, and extraction processes such as extraction of antioxidants, extraction of oil and protein from algae, extraction of sugar from sugar beets and extraction of nutrients or fibers from peels and stems. Furthermore PEF processing can be applied for the removal of acrylamide, concentration of protein from potatoes and enhancement of production processes for cooked ham and dry sausage.

Pulsed electric field processing can save time and money and create value by improving product quality. Slow mass transport processes, e.g. during drying of plant or animal tissue, are sped up, allowing a reduction of processing times. Juice or oil extraction yields are increased. Another benefit is the reduction of tumbling times in meat processing because of improvement of brining processes. In dry sausage production PEF technology enhances the drying process, reducing the required drying time.
PEF applied for food preservation produces high quality, fresh like liquid foods and beverages with high nutritional and functional value. Unlike thermal pasteurization PEF does not affect vitamins, proteins and other valuable nutritional and functional components. For heat-sensitive liquid foods where thermal pasteurization is not an option, PEF treatment would be advantageous.
With PEF you can generate and accurately measure significant increases in yield, freshness and flavor preservation across a wide range of food types. PEF brings positive and substantial changes to manufacturing. Improving output, reducing labor costs, streamlining supply chain logistics and curtailing retail waste.

Using PEF systems instead of preheaters has several advantages for potato processing. PEF treatment improves cut quality and significantly reduces French fry breakage. Water and energy consumption are reduced; blanching, drying and pre-fry times are shortened. Furthermore, the leaching of sugars is improved. The treatment can also reduce frying oil absorption and fat content up to 50%.

Electroporation has a targeted impact on cell membranes. Whereas all kinds of vegetative spoilage and pathogenic microorganisms can be inactivated, a limited effect on enzymes, spores and viruses is found. Other constituents such as vitamins, minerals, pigments and flavors are also retained. In contrast to heat treatment the functionality and nutritional value of proteins is hardly affected.

The usage of PEF for food preservation is not limited to mild pasteurization purposes. Food sterilization is possible with PEF in combination with higher temperatures to eliminate spores.

In general, the shelf life of both PEF-treated and thermally pasteurized foods is comparable. Like thermally pasteurized foods PEF-treated products are usually stored refrigerated.

Yes, Pulsemaster has developed industrial scale equipment – named Conditioner – with treatment capacities up to 5,000 l/h (1320 US gal./h) for microbial inactivation and up to 50,000 kg/h (110,000 lb/h) for cell disintegration. Well proven pulse generators and treatment chambers are available. The equipment is industry ready and in compliance with all safety regulations.
PEF systems for the science sector also have been developed. Pulsemaster manufactures a range of PEF systems for science and research organizations, tailored to suit specific research needs. The design of these tailor-made pulsed electric field systems is compact and modular for easy integration and power upgrade. The science systems are both easy to use and easy to service and maintain, thanks to the modular design with field replaceable units.

Yes, as a continuous short-time process with low space requirements pulsed electric field processing can easily be implemented in existing lines. For cell disintegration applications a typical processing line consists of a treatment tank unit and a pulse generator unit. For mild preservation of fruit juices a typical processing line consists of a supply tank, a fluid pump, a pulse generator unit, a cooler (if required) and a buffer tank. The processing line can be CIP (Clean In Place) or SIP (Steam In Place) cleaned.

PEF is a low energy process. Depending on the type of application the specific energy consumption is in a range of 10 to 100 kJ/l (2.6-26.4 KJ/US gal.) of product. The smaller the target cells are, the higher the required treatment intensity is. On a commercial scale total costs of 1 Euro/ton (= 0.1 Eurocent per liter or kg) for treatment of plant cells and 10 Euro/ton (= 1 Eurocent per liter or kg) for microbial inactivation have to be expected.
In US Dollar total costs of approximately 0.056 US Dollarcent per lb for cell disintegration and 4.92 US Dollarcent per gallon for microbial inactivation have to be expected on a commercial scale.

Pulsemaster offers customers use of lab sized PEF systems and other lab facilities for test purposes, product and process development and challenge tests. Confidential product evaluations as well as validation of food safety and shelf life can be conducted.

These are difficult to give because of confidentiality issues, but commercial adoption of PEF systems is growing worldwide. To date, several PEF treated juices are available on the market worldwide. For cell disintegration purposes especially potato processors show great interest in PEF technology as an efficient alternative for their preheaters. Potato applications are already operational in the US and Canada. Furthermore, for several years a juice pasteurization application in the US has used PEF. There are also commercial PEF food applications in various countries in Europe, as well as in Australia, India and China.
Our highly skilled engineering experts have deep knowledge and industry experience in designing and building over 70 PEF systems since 2009 for a broad spectrum of applications and outputs in the food industry worldwide. The applied pulse generators have a proven track record for food industry and PEF 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.
Each Pulsemaster PEF system is built with the highest quality German and Dutch engineering to withstand continuous operation (24/24) in industry.

The Novel Food Legislation applies to food products and ingredients of certain categories placed on the market within the European Union (EG 258/97). New production processes for foods have to be evaluated. To be not regarded a novel food they should not cause any significant changes in the composition or structure of the foods or food ingredients which affect the nutritional value, human metabolism or level of undesirable substances. After a PEF treatment no significant changes of the composition or structure affecting nutritional value, metabolism or level of undesired substances have been shown so far. It can be assumed that PEF treated fruit juices are not novel foods.