PurePulse - PEF 2.0
From Top Wiki
The predecessor of PurePulse is PEF. With this continuous process preservation technology, liquid food products are pre-heated slightly and are subsequently pumped through an electric field. Due to exposure to this electric field, bacteria and moulds are inactvated ("killed"). The PurePulse technology, owned by company Cool Wave Processing perfects regular PEF with a number of smart innovations. PurePulse is therefor also known as PEF 2.0. With this technology, one can achieve the same product safety level with less power as well as substantially lower heating, ensuring better preservation of both the product's original fresh nutritional value and sensory properties.
PurePulse is a technology that causes biological cells to be ripped open and perforated. During the process, the biological cells are subjected to an electric field with high field strength, allowing plant and animal cells to be opened up (because of this opening effect, the technology can also be used to support or accelerate certain extraction or drying processes, due to facilitated escape of components from the cell matrix). At higher power settings microbial inactivation will follow; the high electric field perforates the cell membranes of bacteria and thereby causes their inactivation. By making use of intense, but short high frequency pulses, there is only slight heating of the product itself while the bacterial inactivation effect remains. This lack of heating will benefit the sensory quality of the product. In order to generate the pulsed electric field, both a source and a treatment chamber are required. The treatment chamber consists of at least two electrodes, with an insulating region in between, where the treatment of the product takes place
The PurePulse treatment has the following relevant parameters:
- Flow rate: with industrial pulse generators, up to 2000 liters per hour can be treated.
- Pulse frequency: as all the product flows through the treatment chamber, and the entire volume of product needs to be treated in that treatment chamber to be treated, it is very important to set the pulse frequency (and the power) accordingly, in order to ensure even the fastest particle in the product stream is exposed to at least one pulse in the treatment chamber
- Electric field strength: the electric field strength determines whether the cell membrane of the bacteria will be punctured. In the PurePulse process, field strengths are used between 20 and 40 kV / cm
- Preheating: the process is more efficient at higher temperatures. Therefore, the treated product needs to be pre-heated to a temperature between 30 ° C and 60 ° C. These temperatures are substantially lower than those used in the first generation PEF technology
Figure 1 PurePulse system
De PurePulse treatment is a continuous process, not a batch process. PurePulse can be applied to liquid products which do not contain air bubbles or sizeable particles. The maximum allowable size of particles in the product is approximately 2mm x 2mm x 2mm. Furthermore, the product should be able to cope with temperatures around 45-55°C. A product treated with PurePulse is required to be buffered in an aseptic storage tank and subsequently bottled or otherwise filled by using a aceptic or ultra-hygienic filling system.
PurePulse can be used to
- cold-pasteurize products (inactivation of vegetative micro-organisms, moulds and yeasts)
- treat fermentation batter to accelerate growth
- expose intracellular cell material (fermentation batter, processing co-streams)
- increase pressing yield / efficiency for vegetables and fruit (except citrus fruits)
Examples for applications with PurePulse
- Fruit and vegetable juices
- Raw milk and whey
- Tea-like beverages
- Fresh, pre-made cocktails
- Fruit and vegetable pulp
- Wine with low alcohol percentage
- Fresh,wet algae
- Flavours and colourants
As the PurePulse PEF process consists of short electric pulses, only slight heating of the product occurs. This preserves the fresh original character of the product. In 2011, TOP extensively studied the effects of PEF on raw milk, fruit juices, vegetable juices and smoothies. A nice overview article can be found here.
Pros and Cons
- Low impact of heat
- Fresh character of product preserved
- Little energy compared with traditional thermal treatments
- Only for pumpable products
- Viscosity and size of particles in product pose a restriction
- Purchase price is higher than traditional thermal processing equipment
PurePulse equipment in which the product undergoes only a minimal temperature rise is available at:
PurePulse equipment is available for 600 L/hr, 1200 L/hr en 1800 L/hr (fruit juices, 6-log reduction of yeats and moulds, shelf life >>21 days)
This video clip shows the available pilot at Top B.V. in Wageningen, the Netherlands. In november 2012 the system was adapted to allow full inline cleaning and desinfecting (CIP), making it suitable for small-scale production runs. This pilot is available for application research exclusively for potential customers. The pilot in Wageningen can treat around a hundred to five hundred liters per hour. Products can be filled aseptically in special sterile bags, or manually in bottles through a flowline, which also makes glass containers an option.
The promotional video for PurePulse(version Anuga 2012) can be found below:
The costs of PurePulse treatment are about € 0.04 per liter. The investment costs for the smallest PurePulse machine (350 liter per hour) are about € 350.000. A total production line, including heat exchanger SKID costs about 500.000 to 600.000 euros including installation. Excluded from this investment estimate CIP-system, cold and hot water utilities, presses, aseptic buffer tank with filling system.
Lecture given by Frank Smeltink during Top Technology Talks 2012