267349 Microbial Load Control by Intermittently Delivered Pulsed Electric Fields

Wednesday, October 31, 2012
Hall B (Convention Center )
Alexander Golberg, UC Berkeley, Berkeley, CA

Microbial load control by intermittently delivered pulsed electric fields.


Alexander Golberg


Department of Mechanical Engineering, Etcheverry Hall 6124, University of California at Berkeley, Berkeley, CA 94720, USA.


Abstract: Microbial contamination prevention by intermittent delivery of pulsed electric field (IDPEF) is a new concept and method for turbid products storage. The treatment may be delivered at time intervals that is prescribed by PEF inactivation efficiency and microorganisms' growth kinetics, when known. This approach facilitates sterile storage without the need for chemical preservatives, additives, radiation or the complex infrastructure demanded by constanct connection to the electrical grid, which is not available in many developing countries. Unlike ultraviolet radiation, IDPEF can be used in turbid media. Furthermore, our previous work showed that IDPEF microbial control is comparable with refrigiration. Here, we first discuss the efficient IDPEF protocol desing principals. Second, we present the preliminary, laboratory scale studies of IDPEF application for milk storage. In this work we investigated the impact of IDPEF on Lysteria monocytogines in milk. Using the L. monocytogines kinetics growth data, we designed an IDPEF protocol that consists of 2 sequences of 10 square wave pulses, 50 μs duration, 12.5 kV/cm electric field strength, delivered at 0.5 Hz and 1 min pause between the sequences applied every 1.5 h. In a demonstration, 12 hours experiment, at 320C storage temperature, L. monocytogines concentration of untreated samples reached (9.10.6)∙107 CFU/ml and (7.10.3)∙108 CFU/ml for initial contamination levels of (1.40.2)∙103 CFU/ml and (3.10.3)∙106 CFU/ml, respectively; while the final concentration in the IDPEF treated samples was 12044 CFU/ml and (1.10.3)∙105 CFU/ml. The IDPEF storage method is of particular importance for parts of the world lacking continuous electricity supply, where today's pasteurization technologies use biomass burning that contributes to 4% of global CO2 emissions. Prelimenary life-cycle analyses reveals that an energy needed for IDPEF storage of milk in India can be generated by a small scale 2kW solar energy system operating 5.5 hours per day in combination with small scale energy storage systems.


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