ELEA’s history
The first reports on Pulsed Electric Fields have been published in the 1960s. Ongoing research on PEF use in the food sector from lab to pilot scale reached the German Institute of Food Technologies, DIL, Germany. They develop industrial scale PEF systems since 2006. In a joint project with potato delicacies processor Wernsing an industrial scale unit has been developed since 2010 and been installed in 2012 to improve the cutting and frying process in French fry manufacturing.
Afterwards three further units have been installed in Wernsing production sites in Germany and Denmark. In parallel, the Dutch premium fruit juice supplier Hoogesteger has installed DIL/Elea PEF systems in its production facilities since 2012 for gentle shelf-life extension whilst retention of the natural juice quality. With ongoing success, in 2012 the spin-off entity Elea GmbH has been funded to take over marketing and distribution of PEF systems developed by DIL. To date with over 125 installed systems, Elea is the world’s leading provider of Pulsed Electric Field systems (PEF) to the food, beverage & scientific sectors.
Effect mechanism of PEF
Chips, juices, dried products – the use of pulsed electric fields (PEF) as an innovative technology can be used in a wide variety of areas of the food industry and bioprocess engineering. Influencing the cell structure of the product is the main goal. All cells are surrounded by a membrane whose main constituent is phospholipids. By applying an external voltage so-called electro-compression is caused. This results in the formation of a pore in the membrane (electroporation). In principle, this is a physical cell opening without mechanical cell destruction, whereby enormous process optimizations and quality advantages can be achieved.
Extended durability, intense colour and fresh character of PEF treated juices
PEF can be used as a gentle method of preserving juices. By PEF treatment of juice, unwanted microorganisms lose their natural barrier function, the inactivation of these microorganisms is the result. The key advantage over traditional preservative processes is the lower temperature exposure experienced by the product. Thus, heat-sensitive colours, nutrients and aromas are not affected and are retained. The introduced energy through the PEF treatment leads to a short-term increase in the product temperature, which, however, is generally well below the pasteurization temperature.
PEF treatment happens only within milliseconds, which is a further advantage over holding times of traditional pasteurization. Immediate cooling of the product prevents the holding at elevated temperatures and ensures optimal preservation of the fresh character. Of particular importance to the fruit juice industry are especially thermoacidophilic bacteria, e.g. A. acidoterrestris, which can also form spores. Due to their increased resistance, high temperature and also a relatively long temperature retention time must be used for purely thermal inactivation.
The PEF treatment can be used for the vegetative germs as well as (in combination with mild heating) for the spores. In both cases, the thermal load is significantly lower compared to a purely thermal process, so that the valuable ingredients and also the taste are preserved. Typical processing costs are around 1-2 cents per litre.
PEF allows up to 90% water and energy savings in French Fries industry
In the French fry and chips production the PEF technology is already indispensable. It replaces the classic pre-heater and saves up to 90% of water and energy. The potatoes are not heated, so there are fewer microorganisms and starch in the process water, as a result the process hygiene is significantly increased. The actual treatment takes only a few microseconds and the retention time in the PEF system amounts to only 5-8 seconds depending on the line capacity.
The PEF treatment results in a uniform softening of the potato, so a smooth cut is achieved, the raw sticks or slices are now more flexible and break less, resulting in a higher yield and longer fries. In addition, shapes such as spiral/twister, waffle or wavy cuts can now be realized with significantly less loss for a wide variety of raw materials. Further quality advantages in the end product are an approximately 10% reduction in fat intake during deep-frying. Today, more than 90 PEF systems are in use in the Fries industry worldwide. Typical throughputs range from 1 to 60 t/h.
Additional benefits for vegetable chips production
For vegetable chips the focus is not only on process advantages but principally on improving the quality of the end product. Here, the fat reduction is up to 20%, depending on cut, the raw material and the frying process. Increasing the efficiency of the frying process has a significant impact on the oil content, colour and crispness of the final product. More consistent and lower heat load frying allows improved colour and reduced acrylamide content for products such as sweet potato, carrot, parsnip or beetroot chips. Hence use of PEF brings important quality benefits.
Retain structure, colour and aroma with PEF-assisted drying
High drying temperatures can negatively affect product quality. PEF technology is an efficient pre-treatment for optimizing the drying process with regard to drying time, temperature and product quality for a wide variety of foods, especially fruits and vegetables. PEF induced electroporation opens the cell membrane and increases the internal diffusion in the product, whereby more water is available at the surface for evaporation. Thus, the temperature can be increased at the beginning of the drying to shorten the process or the temperature is lowered in the last drying section.
For e.g. convective onion drying, this results in a reduction of the drying time by approx. 20% with a reduction of the temperature by 10 ° C in the last drying section. This immediately leads to an improved quality and more appealing product, because colour, ingredients, aroma and shape (reduced shrinkage) remain very well preserved. An enhanced drying process and/or product quality is observed for all types of drying, e.g. hot air, freeze, vacuum, microwave or infrared drying.
PEF for extraction of valuable substances
The principle of electroporation for cell disruption and the resulting discharge of cell sap can be used to extract the cell contents, and in particular valuable substances. This can be used for an increased juice yield or acceleration of extraction processes. During juice production, plant cells are generally opened mechanically, thermally or enzymatically to release the cell content (juice). The so-called mash is separated into solid material (pomace) and liquid (juice) using a variety of methods. A physical opening of the cells by PEF simplifies the separation of liquids and solids without using heat, extreme mechanical crushing or enzymes. The advantage of the use of PEF lies particularly in volumetric treatment, the tissue is not only treated on the surface, but all the way through.
Two process applications are basically suitable for pre-treatment:
a) Treatment of the (entire) raw material in a belt system and
b) Treatment of the mash in a continuous tube system.
The use of PEF leads, on the one hand, to an increase in the total yield of valuable ingredients and, on the other hand, process steps can be shortened and new capacities created. For example, the skin and seeds of grapes are at times fermented with the juice for the production of red wine in order to extract the red colour caused by anthocyanins and polyphenols. Direct pressing would result in a white or rosé coloured wine from red grapes (“Blanc de Noir”). Depending on the grape variety, the extraction process takes up to several weeks. With PEF pre-treatment of the mash, the pigments and polyphenols separate out more easily and quickly from the cells. As a result, this process step can be reduced by several days and new tank capacities can be created by the fermentation tanks being freed up earlier.
PEF for improving peeling behaviour
The impact of PEF on plant material is also successfully used to simplify peeling of tomatoes. Whole tomatoes are subjected to a PEF treatment, which then loosens the skin and allows easy mechanical separation from the pulp. So far lye or steam treatments are used for peeling improvement. With only 2 kJ/kg, the energy requirement for PEF is considerably lower than for a steam treatment and no chemical waste streams occur. In addition, the treatment is carried out at room temperature (or even lower), avoiding negative thermal effects on product quality.
Use of PEF in meat processing
In addition to plant cells, animal cells, e.g. meat, can be influenced by PEF treatment. Despite the different structure of meat compared to that of plant cells, PEF also has a positive effect here. A major part of the production of marinated meat products, which are often used in so-called ready-to-eat products, is the so-called tumbling step. In that process, the meat and the brine or marinade is rolled in a tumbler in a vacuum for a certain time. The PEF treatment changes the structure so that the brine is absorbed more quickly, enabling the tumbling time to be reduced by up to 50 %. This increases the effectiveness of the manufacturing process while also achieving a quality improvement with regard to the tenderness.
The applications for PEF treatment briefly described are very diverse and impressively demonstrate the potential of this technology. Due to the continuous development of not only the food market, but also the pharmaceutical industry, additional applications for the PEF technology will result in future.
PEF systems: CoolJuice™ / SmoothCut™ / PEFPilot™ – description and differences
The systems for PEF treatment generally consist of a pulse modulator and a treatment unit. Elea has developed a range of standardized pulse modulators with different power capacity to suit industrial food processing. Dependent on type of material to be treated a batch or continuous operation is possible.
SmoothCut™
The industrial scale solution for the treatment of tubers, roots, vegetables and fruits. Our SmoothCutTM system is available in a range of four models: the SmoothCutTM One, 10, 100 & 1000. 1t – 70 t per hour processing capacity, quick start-up, small footprint, low energy & water consumption. To treat solid products, e.g. potatoes, the pulse modulator for providing the high-voltage pulses is combined with a treatment belt.
CoolJuice™
For liquid foods & non-foods Elea CoolJuice™ is available in three versions: CoolJuice™ 10, 100, 1000. With capacities from 50 L – 10 000 L per hour. Higher flow rates can be achieved by installing several systems. Hygienic integrated design CIP, SIP ready. For the area of gentle microbial decontamination of juice products, the treatment cells, consisting of two electrodes and an insulator, are integrated in a tube.
PEFPilot™
Our trial batch system can treat solids and liquids for scientific and pilot scale applications. We offer different treatment chamber sizes up to 10 L treatment volume resulting in highest flexibility changing the treatment parameters such as field strength, specific energy input and sample size. We’ve created the Elea PEFPilot™ system to help our clients explore the potential of PEF for their raw products on-site in their laboratory or factory. This trial batch system mirrors the process of the larger belt systems and can be used for research and small production purposes.
Technological and economic impact of PEF technology
Processing of potatoes in French Fries industry has been the breakthrough application for PEF. The major economic benefits results from a reduced energy and water consumption in comparison to conventional pre-heating, an increased product yield and quality and a reduced oil uptake. In the snacks industry PEF also allows an increased yield and quality but also enables the development of new shape or raw material products. Juice industry benefits from an extended shelf life with fresh like product characteristics, less product losses and retail waste.
How is the European and global food market coping with this innovative technology?
PEF has found use in European as well as global food markets. At present Europe and North America are major markets for our systems, whereas South America and Asia show substantial growth.
Is Italian market ready for PEF?
We experience great interest from Italian fruit and vegetable processing industry and have a number of installations in that area. Looking at the variety of products grown and processed in Italy we are confident that further applications will follow.
Stefan Toepfl
Stefan is a food engineer with focus on process and equipment design, process efficiency and targeted energy use in food industry. He headed the Business Unit Process Technologies at the German Institute of Food Technologies (DIL). With a team of scientists, they have developed processing technologies for food industry and equipment manufacturers, including Pulsed Electric Field systems. Since 2017 Stefan is Managing Director at Elea GmbH.
