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					Microwave and RF
Plasma Microwave
Ohmic Heating
Why nonthermal processing?
• Enhance microbiological safety
• Extend shelf life
• Low temperature exposure to food products-
   – minimal effect on heat sensitive components
       • flavor & functional compounds
• Fresh like attributes
• Shelf stable products can be processed by combining with a
  moderate heat treatment. Processing
                High Pressure
            Pulsed Electric Field Processing
                   Ozone Processing
                      Irradiation
       HIGH PRESSURE PROCESSING

Elevated pressures (up to
 120,000 psi or approximately
 900 MPa) with or without
 addition of heat to achieve
 microbial inactivation or to
 alter the food attributes in
 order to achieve desired
 qualities.
• Quality Similar to Fresh Products
   – Juices, Seafood, Jam, Avocado, Oysters, Purees,
     Sauces, Coffee drink
   – Pasteurized and shelf stable high acid food
     products
   – Pasteurized low acid products
   – Shelf stable low acid products

• Equipment/processing costs are
  comparable to similar processes
   – Typically < $.05/lb
                            Semi-Continuous



BATCH




        Concept from Flow International, Kent, WA
                      P1                          P2

                           T
                            m




                                                                 Temperature
                                                   T2
Pressure




           Ts



  Ps                                       Pf
                                                         Tf
           ts              t1               t2      tf
                Come-Up         Hold ing         Decompression
                   Packaging
• Flexible packaging is widely used
   – At least one interface of the package should
     be flexible for pressure transfer
   – Minimize headspace
      • Air has different compressibility than food
            Process and products development
                           NEW




                          PRODUCT
                                    Value
                                    added


  Process OLD   PROCESS
                                            NEW
  related
limitations



                                            Compete
                                             against
                                            existing
                            OLD             product
    MICROBIAL SAFETY

• HPP treatments are effective in
  inactivating most of the vegetative
  microorganisms, with pressures
  between 200 and 600 MPa at ambient
  temperatures.
• Gram-positive organisms are more
  resistant than Gram negatives.
• There can be variations in pressure
  resistances between strains.
                                 Combined effect of pressure and
                                temperature on C. botulinum spore
                                           inactivation


             0
                                                                            •   Achieved a 5-log
                                                                                reduction of type E
             -1
                                                                                spores in phosphate
             -2                                                                 buffer and model food
Log (N/No)




             -3             35oC
                                                                                system such as crab meat
                            40oC
                            45oC
                                                                                blend
             -4
                            50oC
                                                                            •   Spores of nonproteolytic
             -5
                                                                                type B strains (17-B and
             -6
                  550     600      650        700         750   800   850
                                                                                KAP9-B) in both
                                         Pressure (MPa)                         phosphate buffer and
                                                                                crab meat blend offer
                        Reddy et al., 1999                                      higher resistance
                                                                            •   Research is in progress to
                                                                                identify most resistant C.
OSU HPP Facilities




  •HPP pilot plant with kitchen

  •Custom made equipment
  for microbial inactivation,
  in-situ property measurement
  under pressure
        High Pressure Research
           Program at OSU
• High pressure processing of low-acid shelf-stable foods
• Control of food pathogens and spoilage organisms in
  food products
• Mathematical modeling of high pressure process and
  food property measurement under pressure
• Quality of high pressure processed products
• Impact of high pressure processing on packaging
  materials
• Consumer acceptance of high pressure processed foods
• High pressure pasteurization of cheese, milk, and meat
  products
    Pulsed Electric Field Processing

• Application of short burst   Potential Food
  of high voltage (approx.       Applications
  30-50 kV/cm) to foods        • Juice
  placed between two           • Milk
  electrodes                   • Liquid eggs
   – pulses applied at         • Soups
     ambient or                • Syrups, sauces
     refrigerated              • Emulsion
     temperatures for          • Flavor ingredients
     short treatment
     time of seconds or
     less
         Simplified PEF Equipment Layout



   Power         Capacitor
                                   Switch
   Supply        Inductor

Provide Energy   Store Energy   Release Energy



                                   Treatment
                                   chamber

                                  Process Food
    Variables in PEF processing
Primary                       Secondary
• Electric field strength     • Processing/conditioning
   – Average peak field U/d     temperature
   – Uniformity of field      • Electrical conductivity / ionic
• Total treatment time          strength
   – Resident time in PEF     • Growth stage of
     zone                       microorganisms / adaptation
   – Flow velocity profile    • pH
   – Pulse repetition rate    • gas liquid mix
   – Number of PEF
     chambers
        Microbiological Resistance



– Bacteria > Yeasts
– Gram (+) > Gram (-)
– Bacterial spores & Mold ascospores >
  Vegetative cells
– Stationary or Lag growth phase > Logarithmic
  phase
              Mechanism for cell destruction
      a       -         +       b -   +            c            d
                                  -   +
              -         +         -   +
Cytoplasm                 Medium    -   +
              -         +         -   +
                                  -   +
              -         +         -   +

          •   (a) Cell membrane with a potential V’m,
          •   (b) membrane compression,
          •   (c) pore formation, reversible breakdown,
          •   (d) large pores are formed, irreversible dielectric breakdown (cited
              Zimmermann, 1986)
  OSU-6 Commercial Scale PEF processing system

Aseptic processing system, 0-60kV output, 75kW, 2-8 chambers, up to 2000L/h
Food products evaluated using PEF at OSU

 •   Orange juice      •Wheat grass juice
 •   Tomato juice      •Milk
 •   Apple cider       •Chocolate milk
 •   Peach nectar      •Soymilk
 •   Yogurt drink      •Enriched soymilk
 •   Beer              •Rice pudding
 •   Apple sauce       •Liquid egg
 •   Salsa             •Liquid egg white
 • Salad dressing      •Liquid egg Yolk
      How can we help you?

•   Technology evaluation
•   Lab scale studies
•   Pilot scale product tests
•   Product development technology
•   Evaluation of processing effects
    on food attributes
                                SUMMARY
– Nonthermal processing technologies offer UNIQUE
  opportunities and challenges.

– Nonthermal technologies such as high pressure processing
  likely to be used commercially before it could be well
  understood scientifically to exploit its full potential.

    • Refrigerated products are commercially available.

    • Shelf-stable low-acid foods require further research and regulatory
      approval.

    • Identification of suitable products is critical.
 …a safer world through food
safety and technology research

                  Thank you!
       High voltage arc discharge




http://www.designer-bg.com/tok-v-gazove/en/images/dygov.gif
Pulsed light
Oscillating magnetic fields
Irradiation

				
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posted:1/19/2012
language:English
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