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Numerical evaluation of lactoperoxidase inactivation during continuous pulsed electric field processing

Authors

  • Roman Buckow,

    Corresponding author
    1. Commonwealth Scientific and Industrial Research Organisation, Animal, Food and Health Sciences, Werribee, VIC 3030, Australia
    • Commonwealth Scientific and Industrial Research Organisation, Animal, Food and Health Sciences, Werribee, VIC 3030, Australia
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  • Julius Semrau,

    1. Dept. of Food Biotechnology and Food Process Engineering, Berlin Institute of Technology, Berlin 14195, Germany
    Current affiliation:
    1. Schwartauer Werke, Schwartauer Allee, 23611 Bad Schwartau, Germany
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  • Qian Sui,

    1. Commonwealth Scientific and Industrial Research Organisation, Animal, Food and Health Sciences, Werribee, VIC 3030, Australia
    Current affiliation:
    1. Institute for Food Safety and Health, Illinois Institute of Technology, Bedford Park, IL 60501-1957, USA
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  • Jason Wan,

    1. Commonwealth Scientific and Industrial Research Organisation, Animal, Food and Health Sciences, Werribee, VIC 3030, Australia
    Current affiliation:
    1. Institute for Food Safety and Health, Illinois Institute of Technology, Bedford Park, IL 60501-1957, USA
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  • Kai Knoerzer

    1. Commonwealth Scientific and Industrial Research Organisation, Animal, Food and Health Sciences, Werribee, VIC 3030, Australia
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Abstract

A computational fluid dynamics (CFD) model describing the flow, electric field and temperature distribution of a laboratory-scale pulsed electric field (PEF) treatment chamber with co-field electrode configuration was developed. The predicted temperature increase was validated by means of integral temperature studies using thermocouples at the outlet of each flow cell for grape juice and salt solutions. Simulations of PEF treatments revealed intensity peaks of the electric field and laminar flow conditions in the treatment chamber causing local temperature hot spots near the chamber walls. Furthermore, thermal inactivation kinetics of lactoperoxidase (LPO) dissolved in simulated milk ultrafiltrate were determined with a glass capillary method at temperatures ranging from 65 to 80°C. Temperature dependence of first order inactivation rate constants was accurately described by the Arrhenius equation yielding an activation energy of 597.1 kJ mol−1. The thermal impact of different PEF processes on LPO activity was estimated by coupling the derived Arrhenius model with the CFD model and the predicted enzyme inactivation was compared to experimental measurements. Results indicated that LPO inactivation during combined PEF/thermal treatments was largely due to thermal effects, but 5–12% enzyme inactivation may be related to other electro-chemical effects occurring during PEF treatments. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012

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