VMT Symposium New Technologies 160410 Toepfl


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By pulsed electric field (PEF) application a preservation of heat sensitive products such as fruit juices,
smoothies and emulsions can be achieved. Making use of a non-thermal inactivation of spoilage and
pathogenic microorganisms allows retaining the nutritional and sensorial product quality and natural

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VMT Symposium New Technologies 160410 Toepfl

  1. 1. Preservation of heat sensitive media by pulsed electric fields Stefan Toepfl
  2. 2. Facts and Figures Institute FOUNDED IN. 1983 LEGAL FORM. Registered association (e.V.) EXECUTIVE DIRECTOR. Dr.-Ing. Volker Heinz MEMBERS. Approx. 113 member companies (53 of them from Lower Saxony) EMPLOYEES. Approx. 117 BUDGET 2009. Approx. 6.5 million Euro OBJECTIVE. Improvement of efficiency and increase of competitiveness of companies from the food industry MISSION MISSION INNOVATION – Knowledge for superior foods
  3. 3. Market development Food industry DIL
  4. 4. DIL e.V. Member companies
  5. 5. <ul><li>Increased competitiveness through efficiency improvements of the production processes used, e.g. by improved energy management, automation or application of novel technologies on material conversion. </li></ul><ul><li>Support of the industry with new production processes Focus of development: </li></ul><ul><ul><li>Pulsed electrical fields </li></ul></ul><ul><ul><li>Extrusion </li></ul></ul><ul><ul><li>High pressure </li></ul></ul><ul><ul><li>Ultrasonic/shock waves technology </li></ul></ul><ul><ul><li>Application of supercritical fluids </li></ul></ul>Quelle Fotos: DIL, Business Field Process Development
  6. 6. Pulsed Electric Fields Processing
  7. 7. Pulsed Electric Fields (PEF)
  8. 8. Impact of PEF-treatment (2 kV/cm) on Jona Gold (JG) and Golden Delicious (GD) juice yield using a decanter centrifuge. Juice yield including an eventual transition of solids to juice PEF treatment of plant tissue Quantification of relevant interactions – technical scale
  9. 9. PEF treatment of plant tissue Application to key elements – pretreatment (Günther, 2008) Kea-Tec Electroporator (Müller et al. 2007) 10 t/h installation in German fruit juice company Premium cloudy juice production, using continuous belt press yield increase + 4 to 6 % in comparison to untreated Subsequent enzymatic maceration yield increase + 0 to 2 % Shift to higher production of premium quality first press Energy input: 4 to 6 kJ/kg
  10. 10. Olive oil recovery spain Replacement of malaxation process with same yield PEF treatment of plant tissue Application to key elements – pretreatment
  11. 11. Anthocyanin and polyphenol extraction from grapes Lopez et al. 2008 Separation: PEF treatment of plant tissue
  12. 12. Separation: PEF treatment of microalgae Extraction of functional compounds from microalgae Koehler, Toepfl et. al. 2006 Component Chl. dm BM Chl . dm PEF BM Yield increase % Chlorella Spir . dm BM Spir. dm PEF BM Yield increase %Spirulina Protein g/100g 5,48 6,98 + 27 33,68 38,12 +13 Chlorophyll g/100g 0,011 0,1 + 809 0,17 0,26 + 52,9 Carotenoids g/100g 0,008 0,05 + 525 0,044 0,11 + 150 Protease Unit/100g 204,7 707,2 + 245,5 864,2 812,5 - 6
  13. 13. Electrifying microbes… Cell membrane permeabilization Loss of cytoplasma Loss of vitality Treatment conditions Electric field 30 kV/cm Peak current 500 A Pulse repetition ~ 100 Hz
  14. 14. Inactivation of E. coli, L.innocua, S. cerevisae and B. megaterium in ringer solution with an electrical conductivity of 1.25 mS cm -1 after PEF treatment with graphite anode and a field strength of 16 kV cm -1 Inactivation of different microorganisms Variations in resistance against PEF
  15. 15. Impact of processing parameters – process and equipment design Field strength, energy input and temperature Calculated specific energy consumption for a reduction of E. coli in apple juice at different electric field strengths and temperatures as function of treatment temperature (a) and field strength (b). Energy consumption to obtain inactivation 3, 5, 7 and 9 log-cycles at a field strength of 42 kV/cm as function of treatment temperature (c). a b c Electrifying microbes…
  16. 16. E. sakazakii Infant formula 30 kV/cm rectangular 10 µs width 3.5 log-cycle inactivation below 72 to 75°C Protective effect in comparison to Ringer solution (dotted lines) L. monocytogenes
  17. 17. L. monocytogenes Thermal inactivation kinetics in relevant T and t range T: 40 – 75°C t: 1 – 20 s
  18. 18. Thermal inactivation Product deterioration Goal: 3.5 log-cycle inactivation of E. sakazakii in infant formula Microbial inactivation by PEF Quantification of relevant interactions–thermal effects
  19. 19. 15s Comparison to thermal portion of inactivation Protective effect in comparison to Ringer solution (dotted lines) E. sakazakii L. monocytogenes
  20. 20. „ Gentle killing“ of bacteria Shelf life increase of fresh, non-pasteurized smoothies and other heat sensitive media
  21. 21. „ Gentle killing“ of bacteria Inactivation of yeasts and molds in cocktail premixes
  22. 22. PEF –equipment – Why pulsed energy? 20 kV at 100 Ohm resistance: Electric power: Electroporation takes places after 1 µs Energy delivered in form of pulses (µs), to limit electric power consumption “ Concentration” of specific energy U (kV) T (s)
  23. 23. Electrical energy is stored in a capacitor and discharged into the treatment chamber Dependent on switching technology and discharge circuit different pulse wave shapes can be obtained Differences in peak power capabilities PEF – Pulse Modulation RC-series PFN Transformer Marx-Generator
  24. 24. Exponential decay micro- pulse modulator, 16 kV, 100 J/s Exponential decay lab scale pulse modulator, 16 kV, 800 J/s Exponential decay technical scale pulse modulator, 24 kV, 8000 J/s Rectangular technical scale pulse modulator, 50 kV, 7000 J/s Exponential decay technical scale pulse modulator, 20 kV, 5500 (40000) J/s Equipment design 2005
  25. 25. 5 and 30 kW systems Capacity up to 15 t/h Rectangular pulses, bipolar Peak voltage 25 kV Pulse width 4 to 30 µs Pulse repetition 0 to 1.000 Hz Detection of peak voltage and current Titanium electrodes Al 2 O 3 insulator
  26. 26. Treatment homogeneity – design of chambers Electric field distribution conductivity Flow pattern viscosity, flow rate Distribution of energy dissipation Treatment efficiency distribution Thermal effects distribution Product – dependent chamber geometry
  27. 27. <ul><li>Possible electrochemical reactions at electrode/media interface </li></ul><ul><li>Anode Cathode </li></ul><ul><li>2 H 2 0 ____ > 2H + + 2HO° + 2e - 2H + + 2e- ____ > H 2 (g) </li></ul><ul><li>2 HO° ____ > H 2 O 2 Reduction </li></ul><ul><li>H 2 O 2 ____ > O 2 + 2H + + 2e - </li></ul><ul><li>2Cl - (aq) ____ > Cl 2 (g)+2e - </li></ul><ul><li>Fe(s) ____ > Fe 2+ (aq)+ 2e - </li></ul><ul><li>Oxidation </li></ul><ul><li>At high current rates (A/cm 2 ) reactions will occur unselective in order of availability of substances ____ > mainly electrolysis of water </li></ul>Electrochemical reactions
  28. 28. Electrochemical reactions Anode Cathode Stainless steel Titanium Fe(s) -> Fe 2+ (aq)+ 2e- Ti(s) -> TiO 2 (s) + 2e- Oxidation
  29. 29. Electrochemical reactions and juice quality Juices compliant with AIJN code of practice Schilling et al., 2008 Parameter Method Soluble dry matter Refractometry pH Porentiometric (IFU-Method Nr. 11) Density Density Measurement Total acid Titrimetric (IFU-Method Nr. 3) Sugar (glc, frc, saccharose) Enzymatic (Testkit; R-Biopharm AG, Darmstadt, Germany) Ascorbic acid Enzymatic (Testkit; R-Biopharm AG, Darmstadt, Germany) Sorbit Enzymatic (Testkit; R-Biopharm AG, Darmstadt, Germany) L-malic acid Enzymatic (Testkit; R-Biopharm AG, Darmstadt, Germany) Phenolic compounds HPLC (DAD, MS) Total phenolics Folin-Ciocalteu Antioxidant capacity TEAC, FRAP, DPPH Browning index Photometric (420 nm) Color L*a*b*-values (Photometric) Turbidity distribution Mastersizer Turbidity stability Centrifugation, storage tests
  30. 31. Cost effective, short-time cell disintegration technique, improvement of mass transfer processes Highly effective microbial inactivation, low maximum temperature and residence time Equipment available at DIL, worldwide a dozen systems operational. Application of Pulsed Electric Fields - Conclusions
  31. 32. DIL Pilot Plant What else?
  32. 33. Meat tenderization Oyster shucking GPa pressure, but µs timescale Shockwave Processing Pilot Plant
  33. 34. 55l technical scale system 600 MPa ambient High Pressure Processing Pilot Plant
  34. 35. Water Pectin solution Reactor V = 16 ml Membrane pumps Treated OGA-solution Supercritical water Pilot plant
  35. 36. Single screw Extruder (Brabender) 2 twin screw extruders (Berstorff / construction of DIL) Planetary gear Extruder (ENTEX) Extrusion Pilot plant single screw ice cream extruder (construction of DIL)
  36. 37. German Institute of Food Technologies (DIL) Prof. Dr.-Ing. Stefan Toepfl Professor-von-Klitzing-Str. 7 D-49610 Quakenbrueck Tel.: +49 (0) 5431 183 140 email: s.toepfl@dil-ev.de www.dil-ev.de Contact Promatec Food Ventures BV Mark de Boevere   Rootven 24a NL-5531 MB  Bladel Tel: +31 (0)497 33 00 57 mark.deboevere@ promatecfoodventures.com www.promatecfoodventures.com