Application potential and commercial experience with
pulsed electric fields in food processing
Stefan Toepfl

Situated in the hotspot of German food production…
95 employees
6 Mio. € turnover
60 % bilateral projects
30 % public projects
active for 600 companies

Non-Profit Membership Organization

Mechanisms of Action

Emerging Technologies…
G.C.Hahn R.Koch VanErmengem
L.Pasteur Esty & R.Rausing
N.Appert
Meyer
1795 1876
Heat 1848 1951
1857 1895
1922
Van´t Hoff Bridgmen Industrial
B. Hite V Platen Equipment
HPP 1885 1904 1954
1899
Flaumenbaum Sale Krupp
Electropure Doevenspeck
PEF 1920 1948
1958 1986
1967
Roentgen Prescott
Bequerel Gewürzmüller
Irradiation 1895
1896 1904 1957
1800 1850 1900 1950 2000

PEF – Application in Food Processing
Applications and processing parameters

PEF treatment of plant tissue
Quantification of relevant interactions – technical scale
80
70
60
50
juice yield [%]
40
30
20
10
0
JonaGold
2 kJ/kg
10 kJ/kg
20 kJ/kg
enzyme
5 kJ/kg
10 kJ/kg
15 kJ/kg
enzyme
JG + GD
control
control
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
Application to key elements – pretreatment
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
Kea-Tec Electroporator (Müller et al. 2007)

Separation: PEF treatment of plant tissue
Quantification of relevant interactions – technical scale
Polyphenol extraction from Red Boskop apple
Schilling, Toepfl et. al. 2007

Separation: PEF treatment of plant tissue
Anthocyanin and polyphenol extraction from grapes
Lopez et al. 2008

Separation: PEF treatment of microalgae
Extraction of functional compounds from microalgae
Component Chl. dm Chl. dm Yield Spir. dm Spir. dm Yield
BM PEF BM increase BM PEF BM increase
% %Spirulina
Chlorella
Protein 5,48 6,98 + 27 33,68 38,12 +13
g/100g
Chlorophyll 0,011 0,1 + 809 0,17 0,26 + 52,9
g/100g
Carotenoids 0,008 0,05 + 525 0,044 0,11 + 150
g/100g
Protease 204,7 707,2 + 245,5 864,2 812,5 -6
Unit/100g
Koehler, Toepfl et. al. 2006

PEF treatment of plant tissue
Application to key elements – pretreatment
Olive oil recovery
Replacement of malaxation process with same yield

tabletop device
PEF treatment of plant tissue
Sensors
Impedance analysis to evaluate tissue integrity
Zp1,00 100 [%]
0,90 90
CDI Zp
0,80 80
0,70 70
0,60 60 CDI Zp
0,50 50 (related to
0,40 40 juice)
0,30 30 juice yield
0,20 20
w/ w [%]
0,10 10
0,00 0
coa P P P fr fi e ju
rse EF 3,6 EF 7,3 EF 10 ozen ne gr nzym ice
grin 6 [ k 1 [ k ,97 -18 ind e
din J J [ kJ ° ing
g / kg] / kg] / kg C
]
Impedance analysis of apple tissue after PEF treatment; juice yield determined by centrifugation handheld device

Application of Pulsed Electric Fields – Treatment costs
ELCRACK ELCRACK ELCRACK ELCRACK
Model 5 kW 5 kW 30 kW 30 kW
Application Tissue disintegration
Average power kW 5 5 30 30
Chamber diameter mm 10 10 50 50
Electric field strength kV/cm 25 25 6 6
Specific energy kJ/kg 5 10 5 10
Operation
per day h 20 20 20 20
per year h 4400 4400 4400 4400
Investment and operation
Investment i. k€ 85 85 185 185
Depreciation y 5 5 5 5
Capacity
Production kg/h 3600 1800 21600 10800
Daily production t 72,0 36,0 432,0 216,0
Operarion costs per kg
Depreciation €-cent/kg 0,078 0,157 0,033 0,065
Maintenance/wear €-cent/kg 0,002 0,008 0,001 0,003
Energy €-cent/kg 0,021 0,042 0,021 0,042
Total €-cent/kg 0,101 0,206 0,054 0,110
Total per t €/t 1,011 2,061 0,543 1,102
Energy costs €/kWh 0,120

PEF Processing of Meat
Potential applications of PEF tissue disintegration
Drying Enhancement
Raw Products (Salami type sausages, Parma or Serrano Ham)
Brining / Injection
Cooked Products (Prosciutto type)
Tenderization/Curing
Beef Meat

Mass transport in meat tissue
Freezing/Thawing
Energy and time-consuming ( >> 330 kJ/kg)
Microbial contamination during thawing
Salt diffusion in meat, fresh and frozen (Brandscheid, Honikel et al.
1998)
Impact of a PEF-treatment on the
structure of chicken meat (1.6 kV, 40 p)
(Gudmundsson 2001)

PEF – Treatment of meat tissue
Impact on dry-cured ham production
control hand salted
110 control brine injection
4 kV/cm, 20 kJ/kg, injection
100 4 kV/cm, 20 kJ/kg hand salted
3 kV/cm, 5 kJ/kg, injection
relative weight [%]
90
3 kV/cm, 5 kJ/kg, hand salted
80
70
60
50
40
0 50 100 150 200 250 300 350
drying time [h]
Drying of pork shoulder after hand salting (approx. 10 % of weight on surface) or
saturated brine (approx. 8 %) injection after a PEF-treatment at different intensity in
comparison to untreated control. Drying at 8° 95 % rel. humidity
C,

PEF – Treatment of meat tissue
Impact on meat pickling/curing
1,30
1,25
1,20
relative weight [%]
1,15 PEF
1,10
1,05
1,00 control
0,95
0,90
fresh injection tumbling/curing cooking
Relative weight development during production of cooked ham
in relation to fresh weight. Injection: 22 % brine with 1.5 %
phosphate addition, 2 h tumbling and 4 h curing, cooking up to
64° core temperature
C
PEF Control

PEF Treatment of Meat Products – REM Micrographs
Improvement of water
binding indicated by
swollen, sponge-like
tissue structure
100x
Improved micro-
diffusion of brine
Improved water
binding due to
interaction between
protein/salt/phosphate

PEF – Treatment of meat tissue
Impact on meat water binding capacity
Improvement of
mass transfer
in meat tissue
•Increase of water
loss after PEF
•Improvement of
water binding
capacity in
combination with
binding agents
Impact of PEF-treatment phosphate (PO4)
addition on weight yield after cooking of
pork shoulder. Injection of 25 % brine, 2 h
tumbling.

Equipment development at DIL
Concept for treatment of meat
pieces

Application of Pulsed Electric Fields
Gentle Juice Preservation
Non-thermal effect on microorganisms
control
Potential to achieve microbial
decontamination at low thermal load
Example:
PEF-Treatment of S. cervisiae in fruit juice
PEF-treated

Application of Pulsed Electric Fields
Gentle Juice Preservation
Inactivation of different microorganisms
0 0 0 0
35°C
-1 -1 -1 -1 45°C
55°C
-2 -2 -2 -2
-3 -3 -3 -3
lg (N/N0)[-]
-4 -4 -4 -4
-5 -5 -5 -5
-6 -6 -6 -6
E. coli L. innocua S. cerevisae B. megaterium
-7 -7 -7 -7
0 40 80 120 0 40 80 120 0 40 80 120 0 40 80 120
-1
Specific Energy [kJ kg ]
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

Integration of temperature-time-profile
Evaluation of thermal and PEF effects
Determination of c-value
3.5 log-cycle of E. sakazakii
Thermal inactivation
tx
N ∫ − k(T(t))dt
(t ) = e 0
N0
k = e a ⋅T - b
Product deterioration
t T − Tref
c - value = ∫ 10 z
dt
0

E. sakazakii
Comparison
to thermal
portion of
inactivation
L. monocytogenes
15s
Protective
effect in
comparison
to Ringer
solution
(dotted lines)

Solid state pulse modulator, based on transformer typology
Rectangular pulses, bipolar
Peak voltage 25 kV
Pulse width 4 to 30 µs
Pulse repetition 0 to 1.000 Hz
Touch Screen, measurement of peak voltage and current
Flowmeter, calculation of specific energy input
Titanium electrodes
Al2O3 insulator

Different treatment chamber modulels available

5 kW technical scale system
30 kW industrial scale system

Applicability of novel technologies for food preservation
Oliven Äpfel
Mikroorganismen
Fleisch
Wein
Mechanism Membrane Protein DNA
Membrane Makro molecules
Operation continuous batch continuous
Products liquid liquid/solid liquid/solid
packed packed
Installed units 3 130 170
Capacity 2.000 l/h 2.000 kg/h 10.000 kg/h
Disadvantage only vegetative discontinuous Acceptance
microbes Oxidation

Cost comparison of different novel techniques
Assumptions:
Thermal
Liquids, with heat
recovery
PEF
liquid food, 50 –
500 kJ/kg
HHP
600 MPa, 5 min
HPT
700 MPa, 5 min
Irradiation 5 – 10
kGy

Application of Pulsed Electric Fields - Conclusions
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

Pulsed Electric Fields (PEF)
E < Ecrit Intact
E cell
E > Ecrit Reversible
E >> Ecrit Irreversible
Key elements: Localized effect on cell membranes
Affecting cell/tissue integrity
Improvement of mass transport

THANK YOU FOR YOUR ATTENTION
DIL German Institute of Food Technologies
Stefan Toepfl
s.toepfl@dil-ev.de www.elcrack.de
T 0049 5431 183 140
DIL is represented in the Benelux by:
Promatec Food Ventures BV
Mark de Boevere
mark.deboevere@promatecfoodventures.com
www.promatecfoodventures.com
T 0031 497 33 00 57