Electroporation is the process of forming pores in cell membranes using electric fields. It is an exciting way forward for extraction of juices and other valuable compounds from plants and microorganisms. Traditional methods like thermal heating are more energy intensive and cause loss of flavor while increasing production of acrylamide and toxins in processed foods. Electroporation mitigates most of these problems, and provides additional benefits like enhanced antioxidant and bioprotective capacity, digestibility and food safety while preserving flavors.
Currently, electroporation with pulsed electric fields (PEF) has seen limited use in juice pasteurization in the US, but is commonly used in potato processing and juice extraction in multiple parts of the world. PEF is also adaptable to use in extracting sugars from sugar beets and sugarcane. Voltages used in PEF are application dependent and vary from 200 V/cm to as high as 35,000 V/cm. Such high voltages are energy inefficient and can be unsafe to the user. A safer and more energy efficient means of electroporation would be greatly beneficial in the field.
The University of Texas at Austin has developed an alternative to electroporation using PEF, by replacing it with pulsed magnetic field (PMF). The required electric field is generated using PMF through closed magnetic yoke, such as a toroid placed in the flow path of a fluid medium to be processed. The electric field is concentrated in the annulus that is in direct contact with the fluid. Multiple toroids can be used to increase electroporation throughput. The power required to generate the maximum flux through the system is considerably less than that required in a conventional apparatus. Another advantage is elimination of electrode contamination and corrosion.
An embodiment of this invention is shown below; additional details may be found in the issued patent. The toroid used had a cross-sectional diameter of 2’’ with a 6’’ diameter annulus. The toroid was excited by electric current at 10MHz, and an induced electric field was generated along the radius of the annulus. The magnitude of electric field generated by the toroid is highest at the center of annulus and decreases exponentially toward the edge of the toroid, as expected. The power to excite the toroid is proportional to the current flow in the fluid medium, which in the experiment performed has a conductivity of 0.15 S/m. The major advantage is the ability to concentrate electroporation within the center of the annulus and completely avoid all half reactions. Also shown is a cross sectional view of sample passing through two toroids.