Sponsored International Sugar Journal

PEF technology for sugar beets processing

Introduction

The innovative Dutch-German company Pulsemaster recently introduced a new generation PEF (pulsed electric field) technology claiming that it can significantly improve sugar beets processing. The Pulsemaster PEF technology (figure 1) induces poration of sugar beets cells, leading to cell disintegration. This ‘cold’ extraction prevents thermal degradation of the cell wall and the extraction of components such as pectins, oligo- and polymolecular compounds into the juice and makes the pulsed electric field systems an alternative to diffusion towers in the sugar beet industry.

Figure 1. Pulsemaster’s transport system with PEF treatment chamber

Processing parameters

Using industrial thermal extraction process at high temperatures in sugar beets processing can accelerate various chemical reactions between extracted components of the cellular juice, e.g. colour development due to Maillard reaction. The application of high temperatures also implies a significant consumption of energy and water. More over high temperatures favour the growth of thermophilic flora in the diffusers, which degrades saccharose and reduces sugar recovery.

The application of PEF inducing electroporation of the cell membranes considerably enhances the diffusivity of valuable components in the plant tissues at ambient temperatures. Thus, this PEF-technology is very attractive for extraction of pure dry matter, carotenoids, vitamins, sucrose, proteins, inulin and other useful components. The PEF treatment – claims Pulsemaster – can improve the leaching of sugars in sugar beets cells and significantly reduce energy costs. Water and energy consumption in sugar beets processing are reduced; extraction temperatures and diffusion times are decreased, a lower quantity of impurities like pectin in the juice and less intense juice color after cold diffusion. Furthermore, the quality of the sugar crystals is improved.

Energy efficient, compact and hygienic

The PEF-treatment can reduce the energy consumption by up to 50 per cent and less impurities compared to those obtained using industrial thermal diffusion.

PEF technology is a suitable alternative for intensifying the extraction of compounds through solid-liquid extraction Pulsed electric fields technology consists in the application of short duration pulses (microseconds) of high electric field strengths (0,1 to 60 kV/cm) to products transported between electrodes at room temperature. Short, high intensity field strengths cause electroporation of cells and an increase in their permeability. Pulsemaster’s technical improvement of the PEF concept is based on a more energy efficient process than the previous generation. This means that the new equipment gives better pulse treatment for sugar beets with a more compact PEF-system. The pulse generator is combined with a robust and hygienic transport system and a PEF treatment chamber.

PEF processing is a continuous process and the Pulsemaster PEF-systems can be implemented in existing processing lines. The range of industrial-scale equipment – named ‘Conditioner’ – has treatment capacities from one ton an hour to 70-80 tons an hour for sugar beets processing systems. On a commercial-scale, total costs of 1 Euro/tonne can be expected, states Pulsemaster.

Pulsemaster aspires to further growth in the sugar beet, potato, fruit and vegetable industry. The company has rapidly developed its export activities. Pulsemaster offer global support. In Lohne (Oldenburg), in Lower Saxony, Pulsemaster has an office for the German market at its disposal. “Worldwide the sugar industry – and the potato industry in particular – shows great interest in our industrial PEF-systems,” said Pulsemaster’s Managing Director Mark de Boevere. He also answered a few additional questions from International Sugar Journal in order to clarify the PEF process.

ISJ: Today pulse generators (‘pulsed power’) have a proven track record for industry, research, medical and defense applications. PEF processing to make food products – how do sugar beets fit into that category?

Mark de Boevere: Sugar beets are considered excellent conductors because they are uniformly solid, contain about 75 per cent water and are rich in potassium. By permeabilizing cell membranes, PEF enables tissue softening and enhanced mass transport, resulting in the improved cutting of sugar beets, higher product quality and increased process capacity. Osmotic pressure or turgor pressure in the cells (turgidity) has been reduced by permeabilizing the cell membranes. Sugar beets become more homogeneous with pulsed electric field processing, evening the structure and resulting in the reduction of seasonal variation. PEF technology enables cutting at an optimal product texture. PEF technology provides sugar industry the ability to obtain juices in a selective way, thus avoiding the formation of impurities and reducing the subsequent purification steps; i.e in sugar industry a PEF treatment of sugar beets allows the production of less coloured juices (= less impurities) with higher sugar concentration, which prevents a subsequent purification step and eliminates the pollution associated to these processes.

ISJ: Since when can PEF processing be used on non-liquid foods such as – and particularly on – sugar beets?

Mark de Boevere: An industrial PEF pilot for sugar beet processing (sucrose extraction and purification) with the capacity of 10 tons/h, was introduced only relatively recently, in 2010. The scaling up from laboratory to industrial-level processing requires a corresponding scale-up from several kW to more than 100 kW in terms of power requirements. Today Pulsemaster can scale-up to 150 kW per PEF-system to process solids like sugar beets. For example, McCain in Harnes (France) was the first industrial potato processing company to start with PEF technology for their French fries, in 2010. Today all major potato processing companies have introduced PEF systems for their French fries and e.g. crisps. Improved French fries cutting at an optimum product texture results in less breakage and shattering, producing longer, thinner French fries with smooth surfaces, sharp edges and approximately 40 per cent less cutting force for whole potatoes as the main results. The improved cutting of crisps results in smoother surfaces and less colouration. The subsequent reduced oil uptake and water retention leads to crunchier crisps. In potato mash production, pulsed electric field processing evens out the structural variations in potatoes, resulting in a large reduction in the number and size of lumps and a smoother mash for a better bite.

ISJ: How can PEF-technology contribute to sugar beet processing in terms of innovative equipment and process design?

Mark de Boevere: New equipment design and new techniques need to have a focus on physical processes to maximize the effect of processor’s raw materials. Maximizing the effect of the raw sugar beet material is exactly what we do with our PEF-treatment; i.e. drilling miniscule holes in the membranes of the cells with pulses. In principle, a standard PEF treatment does not affect the taste of the sugar beet relative to an untreated sugar beet. However, a softer tissue structure after PEF treatment allows the use of different sugar beet varieties and cutting technologies to create new opportunities in extraction and purification processes. Conventional beet sugar processing involves slicing beet into cossettes followed by extraction by diffusion in hot water at 70–75ºC, during extracting times of 1–1.5 hours. This temperature permits denaturing of cellular membranes and accelerates the sugar extraction from the interior of cells. This unfortunately leads to release of components such as pectins, oligo- and polymolecular compounds into the juice, which requires complicated and costly purification. The combination of no temperature or lower temperature and electroporation allows obtaining comparable or increased results in terms of sugar yield, but at a much higher juice purity and hence lower energy and material costs for purification. Figure 2 shows a cut through sugar beets before and after treatment by electroporation together with the corresponding moisture imprints left by the samples on a semi-absorbent sheet of coloured paper. The yield of juice obtained by cold pressing of electroporated sugar beet is considerably higher as compared to the control, i.e. nontreated sugar beet tissue. In addition to increased yield of juice, higher transparency of juice indicating higher purity has been obtained.

Figure 2. Sliced sugar beet before and after treatment by electroporation together with the corresponding moisture imprints left by the samples on a semi-absorbent paper

Courtesy of Professor Eugene Vorobiev Univ of Compiegne FR

ISJ: Are there any health risks to the PEF operators or other employees at processing facilities?

Mark de Boevere: There are no health risks for operators and other employees. All our systems are robust with proven solid state components for the pulse generators and a UL- and CE-approved design. The pulse generator is combined with a robust and hygienic transport system with a PEF treatment chamber This pulse generator unit can be installed at a maximum of 20 meters from the transport system. This also allows sugar beets processors to install the pulse generator outside the actual production hall in a climate-controlled corridor and the sugar beets transport system with the PEF treatment chamber inside the production hall.

Under the brand name ‘Conditioner’, we manufacture a range of industrial systems to meet our customer’s production requirements. These turnkey solutions are fully integrated and modular systems for either the cell disintegration of solids or the microbial inactivation of liquids. As a continuous short-time process with low-space requirements, pulsed electric field processing systems can be easily implemented in existing lines. Our modular switching technology enables better pulse control and high reliability. The operation principle of switching is charging capacitors in parallel and discharging in series, directly into the load (treatment chamber). This requires no pulse transformer. Pulsemaster’s Conditioners are built according to the highest quality engineering standards to withstand 24/7 continuous operation and to deliver optimal performance and energy efficiency. Energy is delivered in the form of rectangular pulses with the highest energy efficiency so as to limit electric power consumption.

Pulsemaster BV

Rootven 24, 5531 MB Bladel, The Netherlands
Tel: +31 497 820 300
Email: [email protected] Website: www.pulsemaster.us