Pulsed electric field method

Tsong, T. Y. Tomita, M. Lo, M. M. S. Pre-selection of B-lymphocytes by antigen for fusion to myeloma cells by pulsed electric field method. In Molecular Mechanisms of Membrane Fusion Oki, S. et al., Eds. Plenum New York pp 223-236. 

High hydrostatic pressure (HHP) and pulsed electric fields (PEFs) are rather novel technologies where relatively little research has been carried out. These methods have mostly been tested in combination with other decontamination methods and also mostly on either microorganisms in vitro or on foods of animal origin (e.g. milk, eggs and meat) (Raso and Barbosa-Canovas, 2003 Ross et al., 2003). More research is needed in order to find out if such methods are applicable to the fresh produce industry. 

Pulsed electric field is another alternative to conventional methods of extraction. PEF enhances mass transfer rates using an external electrical field, which results in an electric potential across the membranes of matrix cells that minimizes thermal degradation and changes textural properties. PEF has been considered as a nonthermal pretreatment stage used to increase the extraction efficiency, increasing also permeability throughout the cell membranes. 

Desalting of lysine-rich fermentation broths by monopolar ED appears to be much more rewarding. To mitigate anionic membranes sensitivity to fouling, Lee et al. (2002b, 2003) resorted to pulsed electric field with the halfwave power and suggested the use of pulse power as an effective CIP method during ED of fermentation media. 

Relaxation methods can be classified as either transient or stationary (Bernasconi, 1986). The former include pressure and temperature jump (p-jump and t-jump, respectively), and electric field pulse. With these methods, the equilibrium is perturbed and the relaxation time is monitored using some physical measurement such as conductivity. Examples of stationary relaxation methods are ultrasonic and certain electric field methods. Here, the reaction system is perturbed using a sound wave, which creates temperature and pressure changes or an oscillating electric field. Chemical relaxation can then be determined by analyzing absorbed energy (acous-... 

Another chemical relaxation method that can be used to determine the kinetics of fast reactions on soil constituents is the electric field pulse technique. This technique was developed by Hachiya et al. (1980) to study the kinetics of I03 adsorption and desorption on Ti02 and by Sasaki et al. (1983) to investigate ion-pair formation on the surface of a-FeOOH. Excellent review articles on electric field methods are found in DeMaeyer (1969), Hemmes (1979), and Eyring and Hemmes (1986). 

In order to avoid chemical compounds at all, it is also possible to apply a high voltage to kill microbes on surfaces. It was found that a direct current kills E. coli cells, probably by heat or by hydrogen peroxide formation [84], Microbial cells can be effectively killed by using pulsed electric fields (PEF), probably by frequently disturbing the cell membrane potential [85], PEF that was found to lower microbial cell numbers in food and drinks was also shown to effectively kill E. coli and Listeria innocua cells attached to polystyrene beads [86], This demonstrates the potential of applying this purely physical method to surfaces as well. 

Electroporation-based sterilization of drinking water, wastewater, and seawater has been considered an attractive technology option. An industrial-scale system that utilizes PEE (pulsed electric field) technology results in killing of bacteria in water purification applications surmounting the consumer concern for harmful effects of heat or chemical methods of sterilization. 

Qin, B., Zhang, Q., Barbosa-Canovas, G.V., Swanson, B.G., and Pedrow, P.D. 1995a. Pulsed electric field treatment chamber design for liquid food pasteurization using a finite element method. Transactions oftheASAE 38 557-565. 

Yin, Y, Han, Y, and Liu, J. 2007. A novel protecting method for visual green color in spinach puree treated by high intensity pulsed electric fields. Journal of Food Engineering 79 1256-1260. 

Cell disruption methods can be roughly divided into two categories mechanical ones, e.g., bead mill, homogenizers, and ultrasound and nonmechanicals like organic solvents, osmotic shock, supersonic fluid feed (SFF) and pulsed electric field (PEF). For extracting microalgal components, several methods were applied (Table 2.6). 

Pulse electric field is a technique which uses brief pulses of a strong electric field to perforate the cell wall or membrane. This method has already been applied on microalgae for lipid extraction. Zbinden et al. utilized PEF as a process intensification strategy to enhance lipid extraction from Ankistrodesmus falcatus wet biomass using a green solvent, ethyl acetate. 2 In another study, application of PEF on Auxenochlorella protothecoi-des led to a spontaneous release of intracellular products. ... 

There are two electrical methods used for treating biologicals in water electrochemical and pulsed electric field. Both techniques require generating an electrical field that either directly affects the microorganisms or indirectly creates oxidizing species that affect the microorganisms. They can create mutagenic compounds in the water, have cathodes that tend to foul, and lack any residual effects. Neither has been extensively studied for applications with membranes. ... 

A variety of methods have been demonstrated for biomass deconstruction. These can be broadly classified as chemical, biological, physical, and physicochemical [155]. Chemical methods include steam, lime, liquid hot water, ionic liquids, organosolve, ammonia, oxidative delignification, and ozonolysis [150, 155]. Physical and physiochemical methods include milling, steam explosion (autohydrolysis), ammonia fiber explosion (AFEX), microwave, extrusion, pulsed electric field, pyrolysis, and ultrasound. Consistent with the theme of this chapter, the first description of a novel non-enzymatic biomass deconstruction technique demonstrated the effectiveness of this method by producing ethanol [156]. 

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