Ohmic heating has been revived in the 1980s and after a brief pause in the 1990s, has reemerged in a number of food processing applications. An offshoot, Moderate Electric Field (MEF) processing has emerged from the recognition that even relatively mild electric fields themselves have significant effects on food and other biological materials. A number of significant research areas have been identified in this connection. In addition, a discussion is provided on priorities for federal research funding, including the need for basic research balanced with industry relevance, availability of pilot facilities for development of new technologies, and potentially, a mechanism for helping inventions survive through the initial ``Valley of Death'' phase.

Several extraction techniques have been proposed recently as the food industry is seeking alternatives to tedious classical methods. Moderate electric field (MEF) extraction at low and high temperatures offers several advantages such as enhancing product quantity and quality as well as saving time and energy. This method has gained interest as a preferred extraction technique among researchers. This review is devoted to introducing the principles, mechanisms, and recent progress in the MEF extraction technique. The parameters influencing MEF treatment are also discussed and performances are compared to conventional extraction methods. Considerations for industrial development of MEF as well as its drawbacks are also discussed. MEF extraction is applicable to a wide range of food materials and offers several benefits such as reducing extraction time and energy and also enhancing the extract's quality and yield. Optimizing process parameters, such as treatment time and temperature, electric field intensity, and frequency, along with raw material selection and preparation can boost the performance of a MEF system. Further investigations on safety and sustainability of this novel technique are required prior to commercial applications.

Changes in growth kinetics and metabolic activity of microorganisms under the presence of a moderate electric field (MEF) have been hypothesized as being due to temporary permeabilization of cell membranes. We investigated herein the effects of frequency and growth stage on cell membrane permeabilization of Lactobacillus acidophilus OSU 133 during MEF fermentation. Cells were stained with two fluorescent nucleic acid stains: the green, nonselective, cell membrane permeable SYTO 9, and the red, cell membrane impermeable propidium iodide (PI). Fluorescence exhibition post‐treatment was assessed using fluorescence microscopy. Total plate counting was done to determine whether or not the permeabilized population represented live cells. Fermentation treatments investigated were conventional (control) and MEF (2 V/cm, 45, 60, 1,000, 10,000 Hz) at 30°C. Studies were conducted at 45 Hz for lag, exponential, and stationary phases of growth. Low frequency MEF treated cells exhibited significantly greater numbers of red cell counts than conventional treatments; further, no significant differences existed in viable counts between MEF and conventional treatments, suggesting that the red counts represent permeabilized live cells. MEF treatments at the early stage of bacterial growth at 45 Hz exhibited the maximum permeabilization followed by treatments at 60 Hz. MEF treated samples at frequencies higher than 60 Hz did not exhibit red fluorescence. Cells at lag phase showed the greatest susceptibility to permeabilization followed by those at exponential phase. No evidence of electroporation was observed during the stationary phase. To our knowledge, these observations provide the first evidence that cell membrane permeabilization occurs under the presence of electric fields as low as those under MEF. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009