Pulsed electric field technology (hereinafter - PEF) has been successfully used in the production of potato snacks since 2010. This technology is mainly used in the production of French fries and chips. The successful implementation of PEF equipment for continuous pretreatment of potatoes in the food industry has several benefits in terms of improved raw material utilization, process efficiency and product quality.
Overall, PEF technology replaces the traditional thermal heating of potatoes using up to 90% less water and energy. This technology helps to soften the raw material, allowing for improved cutting and processing of the potatoes. A smoother cut with less surface damage, fractures, small debris and starch loss results in higher finished product yields, less oil absorption and longer cutting knife life. The improved diffusion of water from the PEF of the treated potato allows for an optimized blanching, drying and frying process, which also helps to reduce energy and production costs. French fries and chips treated with PEF are of higher quality and healthier, with a lower percentage of absorbed fat and a more uniform color.
The principle of pulsed electric field processing PEF
The first studies using PEF technology by various research groups were carried out in the early 1900s. However, already at the beginning of the new millennium, the first industrial PEF system was developed and installed in a potato processing plant. More than 150 Elea PEF systems are in use in the food industry today, most of which are installed in the production of French fries and chips.
Pulsed electric field technology is based on the principle of electroporation (Figure 1). Based on physical principles, during the PEF treatment, short electrical pulses of high voltage are generated, which promote the formation of pores in the cell membrane without damaging other valuable substances such as vitamins, minerals or pigments. This technology can be applied to tissues of animal or plant origin and even to microorganisms. All living cells are surrounded by a semi-permeable cell membrane, which mainly consists of phospholipids with dielectric properties. The application of an external electric field leads to an accumulation of charge on the cell membrane and causes an increase in its natural potential, the so-called transmembrane potential. This causes electrical contraction of the cell membrane and, as a result, leads to the formation of pores.
Due to the formation of pores in plant tissue cells (for example, potato cells), during PEF processing, they lose their intracellular pressure (turgor), which leads to softening of tissue and easier and better cutting of plant materials. In addition, electroporation of the cell structure results in improved mass transfer, whereby industrial processes such as washing, blanching and deep-frying are also improved.
Traditionally, the potato industry has used thermal preheating (preheating blanching) to ensure quality cuts, which heats the potatoes to 65 ° C for 45 minutes. This process requires a lot of water and energy. It should be borne in mind that the disposal of microbiologically inseminated water containing starch is often problematic. In addition, filling and discharging water from the heater usually takes a long time and requires subsequent maintenance. This is especially difficult with product changes and unplanned production line stoppages, which often result in the disposal of raw materials.
It should be mentioned that in the production of French fries, the use of PEF processing technology prior to cutting the raw material has already become a world standard. PEF technology replaces the classic thermal heating process, thus reducing water and energy consumption by up to 90%. During PEF processing, the product and process water are practically not heated, which means that there are fewer microorganisms and starch in the process environment. The actual processing takes only a few microseconds and, depending on the production capacity of the line, the potatoes are in the PEF system for only 5-8 seconds. The use of pulsed electric fields also has other advantages. Since this method is bulk processing, all potatoes - whether large or small - are processed evenly. It should be noted that earlier, after thermal heating, the small potatoes were already completely cooked, while the large potatoes were still firm inside. Due to uniform softening, an even cut is achieved; raw french fries sticks are more flexible and break less, resulting in a higher yield of the final product. The reduced oil absorption (by about 10%) during deep-frying reduces the fat content of the final product. In addition, increased flexibility and a smoother surface provide longer french fries sticks and a uniform color with more even browning at the exit.
In the production of chips, the benefits are similar to those in the production of French fries, but the improvement in the quality of the final product is even more pronounced. Slicing is improved, resulting in less raw material and starch wastage during cutting, which in turn leads to a significant increase in yield. The reduction in starch loss is primarily a result of the softened tubers being easier to cut. This, in turn, leads to less mechanical damage to the knives and, as a result, less washout of starch from the surface. Plus, fewer chips stick together during deep-frying, eliminating the need for product rejection. When deep-fried PEF processed raw material for chips, there is a decrease in fat content - up to 20% in the final product, it should be noted that this decrease also depends on the cutting, the quality of the raw material and the frying process itself. The latter plays an important role in improving product quality. The open cellular structure of the raw material and improved water diffusion allow for optimized frying parameters such as oil temperature and frying time. The increased efficiency of the deep-frying process has a large impact on the oil life and oil absorption of the product, as well as the color and crunchiness of the final product. Reducing the time and temperature of frying allows for a lighter product with fewer thermochemical reaction products. This is a great benefit for vegetable chips such as sweet potatoes, carrots, parsnips, or red beets.
In addition, the uniform softening of the raw product opens up new possibilities for cutting products. Currently, in the production of French fries, such forms as spiral, waffle or wavy can be implemented, with significantly less losses of raw materials. Even more alternatives are opening up in the potato chip industry, as harder vegetables such as sweet potatoes, parsnips or red beets can now also be processed to shape. Thus, a greater variety of products appears for the consumer, competitiveness increases, and the production of unusual shapes and / or products becomes more efficient.
Environmental Impact Assessment PEF when processing potatoes
Environmental Impact Assessment (hereinafter - EIA) allows to characterize the impact of production on the environment from raw materials to the final product. An EIA study for the use of PEF in potato processing was carried out on an industrial scale using comparative data from Elea customers around the world, and the study found that replacing conventional thermal heaters with PEF equipment could reduce energy consumption by 85% and water consumption by 90%. which corresponds to 60 - 70 liters of water and 000 GJ of thermal energy savings per year for a typical French fries production line of 000 kg / h. In addition, there is a reduced fat absorption, improved product quality and an increase in product yield by 20-50 ,five%. In addition to the direct benefits of PEF in terms of improving product quality or improving individual production steps, the entire production process becomes more efficient and sustainable. The use of PEF in a continuous production line for standard size chips increases the final product yield by 000 tons and reduces oil consumption by 1 tons. This also reduces the resource and water consumption required for production, in addition, further reducing processing costs, providing the same or even higher industrial capacity. With Elea PEF systems installed around the world in the potato industry today, 1,5 kWh of energy, 67 kg of CO equivalent are saved approximately every second2 and 138 liters of water.
Системы PEF for the potato industry
Elea offers a range of PEF conveyor systems in different sizes with different capacities for french fries and chips lines. In addition, every PEF system manufactured by Elea can be designed and built according to all specific requirements.
All systems can be operated 24/7 and are designed to work in extreme conditions. Thanks to their short processing times of less than 10 seconds and their compact size, Elea PEF systems are easy to integrate into existing production lines. PEF systems are fully automated and can be controlled directly from the production line or remotely from a central control room. All relevant process parameters can be monitored and recorded. Since PEF is the standard in French fries production, the installed system base is constantly expanding, allowing the use of standard components and spare parts in stock. With worldwide partners and remote service capabilities, dedicated engineering support services ensure uptime, XNUMX/XNUMX support and peace of mind.
Elea systems for PEF processing usually consist of a pulse generator and a processing unit. For the processing of solid products such as potatoes, the processing unit is a special conveyor belt. Typical productivity of PEF systems in the production of chips is from 1 to 6 t / h, and when processing french fries, the line capacity is significantly higher at 10-60 t / h.
The Elea PEF Advantage Belt is available in four models: PEF Advantage B 1, 10, 100 and 1000, capable of handling from 1 t / h to 60 t / h.
Especially for small production lines of chips, we have developed the PEF Elea PEF Advantage B 1 and B1 mini systems capable of handling up to 6 t / h of raw materials (Fig. 6).
The average energy consumption of the Elea PEF system is quite low (1 kWh per ton of feedstock), which allows for lower operating costs. Of course, PEF implementation comes with investment and operating costs. However, the installation of more than 30 PEF systems in the chips production has shown a return on investment in a short time frame, averaging one to two years, thanks to savings in process efficiency costs or product-related benefits such as increased yield, fewer scrap and reduced fat content.
In general, PEF technology includes improving the quality of raw materials and optimizing processes throughout the production chain, which benefits the producer, the consumer and the environment.
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