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Critical review of PEF technology |
Q. H. ZHANG, Dept. of Food Science & Technology, Ohio State Univ., 2015 Fyffe Ct., 233 Parker Food Science Bldg., Columbus, OH 43210-1007 Pulsed electric field (PEF) technology has been studied and developed during the last 40 years. It is until recent years, PEF technology emerged from a laboratory concept to a process that can handle a flow rate of interest to industry. With demonstrated product quality and shelf life, PEF process shows the potential as a nonthermal pasteurization method for liquid foods. Further development is expected to fully commercialize this technology. An increased literature is available in PEF inactivation of microorganisms and enzymes. PEF process has been demonstrated to inactivate bacteria, including E. coli O157:H7, Listeria monocytogenes. Inactivation of microorganisms follows nearly a first order kinetics. Electric field strength, total treatment time and processing temperature are critical variables. Equivalency of PEF process to thermal pasteurization is yet to be defined. Inactivation to enzymes is limited to 40 to 90%. PEF process is continuous and best suited for liquid products. Laboratory scale PEF systems are readily available for scientific research. Pilot plant scale and production PEF systems are developed and demonstrated. Pumpable products with significant particles or entrapped gas present challenges to PEF process. Batch process may need to be further developed to handle solid or particulate foods. Consumer studies and economical studies of PEF processing have been initiated. Economical study shows a 7 cents per liter overall PEF processing cost for orange juice including equipment depreciation. This is very close to that of thermal pasteurization of orange juice, approximately 6 cents per liter. With energy regeneration and reduction in commercial equipment cost, processing cost may be reduced to 3 cents per liter in production. PEF processed juice products are rated as high as their fresh counterparts. Negligible amount of off flavor or off taste is generated. Chemical safety of PEF process is not well defined and is an area for future studies.
Session 23, Pulsed electric fields: An update
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