Cold Plasma Sterilization is an method of food preservation. This technology can help to attain newer height and can explore indefinite scope of food preservation for the benefit of people.

1. ANKIT DAYAL
J-13-D-196-A
Ph.D. (FST)
SKUAST-Jammu
COLD PLASMA STERILIZATION - A NOVEL
METHOD OF FOOD PRESERVATION

2. FOOD PRESERVATION
 Processes that help to preserve the food and
extends the shelf-life.
 Canning, drying, freezing, sterilization etc.

3. STERILIZATION
 A process to kill or entirely elimination of
microorganisms from a surface material or medium.
 Types
1. Heat sterilization
2. Chemical sterilization
3. Radiation sterilization
4. Plasma Sterilization

4. HEAT STERILIZATION
 Wet Heat
- applied to the medium in the form of steam.
- Autoclave.
 Dry Heat
- utilizes hot air

5. CHEMICAL STERILIZATION
 Cause reactions among chemical agents and the
cellular chemical bonds of the bacteria
 Used when potential damage caused by heat
treatment is a matter of concern.
 Ethylene Oxide
 Hydrogen Peroxide
 Ozone

6. RADIATION STERILIZATION
 Controlling spoilage and eliminating food-borne
pathogen
 Gamma radiation
 X rays
 Microwaves
 Ultraviolet radiation

7. PLASMA STERILIZATION

8. o Forth state of matter.
• Ionized gas consisting of positively
and negatively charged ions, free
electrons and activated neutral
species (excited and radical) (Sasai
et. al. 2011).
WHAT IS PLASMA

9. PLASMA

10.  Sir William Crookes, in 1879.
 1928, Langmuir and Tonks, while investigating
electric discharges at the General Electric
Research Laboratory, introduced the term
"plasma" to describe the ionized gas.
 Sterilizing properties of plasma was first
introduced towards the end of the 1960’s,
patented in 1968.
HISTORY

11.  Factors affecting plasma
 Choice of Gas:
 Determine effectiveness of sterilization
 Type of active species present.
 Types of free radicals formed are a direct result of the ionized
constituent gas molecules.
 Dictates the intensity and wavelengths of emitted radiation.
 Common gas : O2, CO2, O2/H2, O2/Ar, O2/CF4, and H2O2.
o Gas Flow Rate:
 Increasing the gas flow rate, increases the flux of active species on
the medium, which increases the effectiveness of the treatment
(Lerouge et. al., 2001)
PLASMA STERILIZATION PARAMETERS

12. o Gas Pressure:
 Influences the volatilization rate of the plasma.
 Increasing the pressure can introduce competing effects in the
sterilization process.
o Power:
 Increase in electron density, which allows for a larger volume of
active species to interact with the medium
o Quantity of Material to be Sterilized:
 Higher the quantity, reduced efficiency
 Compensated by gas flow rate and pressure.
CONT..

13. o Nature of Microorganism, Density and Surface Layer
Formation
 Dependence of active species
 Low permeability of plasma
o Packaging
The presence of packaging inhibits the efficacy of sterilization.
o Geometrical Factors
 Reactor design strongly influence the concentrations of
active species
 Direct contact and afterglow
CONT..

14. PLASMA SOURCES
 Corona discharge
 Dielectric barrier discharge
 Gliding arc plasma
generation
 Microwave induced plasma

15. PRINCIPLE
 Cold plasma is generated at atmospheric pressure by passing a process
gas through an electric field.
 Electron arising from ionization processes, accelerated in this field,
trigger impactionisation processes.
 Free e- colliding with gas atoms transfer their energy, thus generating
highly reactive species that can interact with the food surface.
 The e- energy is sufficient to dissociate covalent bonds in organic
molecules.
 Single bonds:1.5 – 6.2 eV, Double bonds: 4.4 – 7.4 eV, Triple bonds:
8.5 – 11.2 eV (Riedel and Jaiak, 2011).

17. CORONA DISCHARGE
 The plasma creates a lighting crown around the wire: that is why this
discharge is called ‘‘Corona’’.
 Adv: High efficiency, low investment & operational cost
 Disadv: Audible noise, power loss, insulation damage of devices
 Uses: Surface treatment for tissue culture, surface treatment of
materials to change properties sanitization of water.

18. MICROWAVE INDUCED PLASMA
 Frequency of 300 MHz to 10 GHz
 Commonly used wavelength is 12.24 cm, corresponding to a frequency of 2.45 GHz
(Bogaertsa et. al., 2002).
 Range from a few Watt up to several hundreds of kilowatts, the discharge pressure
might range from less than 10-2 Pa up to several times atmospheric pressure,
whereas many different discharge gases might be used (E. Timmermans, 1999).

19. CONT..
o Advantages
 wide range of operational conditions
 clean and has high chemical reactivity
o Industrial Uses:
 Ion production
 Analytical chemistry
 Waste treatment
 Surface treatment
 Electromagnetic coating

20. GLIDING ARC PLASMA GENERATION
 Two electrodes diverging with respect to each other placed in fast (typically
10 m/s) gas or vapor flow.
 Application of high voltage between these electrodes creates specific
unstable discharges between electrodes and across the flow.
 The discharges start at the spot where the distance between the electrodes is
the shortest, and spread by gliding along the electrodes in the flow direction
until they disappear after a certain path to repeat this cycle.

21.  Advantages:
 Simplicity
 Low cost
 Environmentally cleaner
 Industrial Application:
 Coating, painting, dying,
and adhesion.
 Plasma based surface
treatments

22. DIELECTRIC BARRIER DISCHARGE
 Parallel plate geometry, with a electrode consisting
of an aluminum plate at ground.
 AC voltage electrode.
 Teflon is used as the dielectric.

23. CONT..
 Advantages:
 High efficiency
 Cost effective
o Uses:
o Food decontamination
o Surface treatment
o Teflon industry

24. Plasma is classified based on the following aspects:
Temperature: Thermal plasma / Hot Plasma
Non Thermal plasma / Cold Plasma
Mode:Microwave
Gliding arc
Corona
Dielectric barrier discharge
Pressure: Low pressure
Atmospheric pressure
High pressure.
CLASSIFICATION OF PLASMA

25. HOT PLASMA
 Temperatures of thermal plasma at atmospheric
pressure generally are above 6000 K.
 Can be indirectly applied to food, i.e. at a distance
from the plasma source ensuring that the
temperature remains within the desired range.
 Applications : Destruction of hazardous waste
 Extraction of metals
 Refining of metals,
 Synthesis of fine ceramic powders
 Spray coatings,.

26. COLD PLASMA
 A cold plasma (CP) is one in which the thermal motion of the
ions can be ignored. Consequently there is no pressure
force, the magnetic force can be ignored and only the
electric force is considered to act on the particles. These
plasmas are said "cold" because the temperature in the
plasma reactor stays near room temperature (Sasai et. al.,
2011).

27. COLD PLASMA STERILIZATION
 Designed for the inactivation of pathogenic microorganisms and food safety
improvement (Niemira, B.A., 2012).
 Ionized gas that comprises a large number of different species such as
electrons, positive and negative ions, free radicals, electrons and gas atoms,
photons and it is suitable to be used in processes for which high temperature
is not recommended (Tendero et. al., 2006; Nehra et. al., 2008).
 Applied in the food industry including for decontamination of raw
agricultural products (apple, lettuce, almond, mangoes and melon), egg
surface and real food system (cooked meat, cheese) etc.

28. EQUIPMENT

29. CP PROCESSING OF FOOD AND FOOD RELATED PRODUCTS
Studied effect Target system
Inactivation of bacteria apples, melons, lettuce, mangos, melons,
bell peppers, apple juice sliced cheese,
ham, almonds etc.,
Inactivation of fungi Hazelnut, peanut, pistachio nut
Inactivation of fungi in seed germination Seeds of wheat, bean, lentils, barley, oats
soybean, chickpea, rye and corn
Degradation of organic compounds/ macro
molecules
Mycotoxins, starch, pesticide and proteins
Diplom et. al., 2010

30. MECHANISM OF MICROBIAL INACTIVATION
 The ability of atmospheric discharge cold plasma to sterilize
surfaces is well established.
 The combination of electron and ion bombardment, thermal effect,
free radical production and local exposure UV (ultra violet).
 All the above act in concert to disrupt microorganisms cell
membranes.
 This leads to changes in microorganisms structure like denature
proteins and damage bacterial DNA

31. Meat
Type
MAP
gas
Initial
bacteria
l
load
Log10
CFU/g
Reduction
day 0
Reduction
end of study
Days
within
accept
able
limits
Curre
nt
shelfli
fe
Target
Shelf
life
Log10
CFU/g
% Log10
CFU/g
%
Lamb
chop
CO2/
O2
5.97 0.17 32 0.30 50 13 8 10-13
Pork
loin
CO2/
O2
5.76 0.81 85 2.58 99.7 14 10 12-15
Turke
y
CO2/
O2
4.94 0.41 61 0.81 84 15-20 21 28-35
• Carmen et. al., 2014
• Shelf-Life
APPLICATIONS: Case Study On Meat

32. A. E.coli
B. Listeria Monocytogenes (Carmen et. al., 2014)

33. CASE STUDY ON RAW CHICKEN
 Campylobacter and salmonella contaminate over 70% of raw
chicken meat.
 Dricks et al. (2012) applied a cold plasma to uncooked chicken for
different time period
 3.5 log reduction of bacteria from both skinless chicken and chicken
skin itself.

34. Plasma
exposure
time (s)
Skinless chicken breast Chicken thigh with skin
Salmonella
enterica
Campylobactor
jejuni
S. enterica C. jejuni
0 7.67 ± 0.29 9.56 ± 0.54 8.00 ± 1.03 8 ± 0.34
5 -b - 7.33 ± 1.13 3.11 ± 0.44 c
10 - - 4.22 ± 0.80 c -
15 - - 6.00 ± 1.32 -
20 - - 3.33 ± 1.49 c -
a- Values are total CFU recovered ± standard error.
b —, no recovery by plating or enrichment.
C, Value shows significant reduction (P ˂ 0.05) from zero exposure time.
Dricks et al.(2012)

35. DECONTAMINATION OF STAINLESS STEEL SURFACE
Treatment
time (min.)
Salmonella Listeria E.coli S.aureus
Low soil Low soil Low soil No soil Low soil No soil
Control
(log)
4.98 4.12 5.05 4.81 6.81 6.41
2 min. ˃3.98 ˃3.42 ˃2.66 ˃2.91 1.54 1.14
5 ˃4.28 ˃3.42 ˃4.35 ˃4.11 1.93 2.11
10 ˃4.12 ˃3.12 ˃4.35 ˃4.11 1.71 2.19
Low soil = 0.3 g/L Bovine serum Albumin (BSA)
No soil = No addition of protein
• Danny Bayliss, 2012
• Campden BRI

36. MICROBIAL DEACTIVATION FROM ALMONDS
 Kalyani et. al. 2012
 Deactivation of salmonella from the surface of almond
 1.5 – 2.5 log reduction

37.  Ragni et. al., 2010
 Maximum reduction of 2.2–2.5 and 4.5 log CFU/eggshell in
Salmonella enteritidis levels following a 90 min of treatment at 35
and 65% RH respectively.
 Salmonella typhimurium, with an overall reduction of 3.5 log
CFU/eggshell, after 90-min treatment.
Case Study On Egg

38. CASE STUDY FOR BACTERIA‐FREE EGGS WITH PLASMA
TECHNOLOGY
 Bradley et. al., 2013.
 Salmonella on egg shells.
 99.5 per cent of bacteria on the egg shell
 Egg yolk and white remain unaffected.

39. WASTE WATER TREATMENT
Raja et al., (2010)
 >5 log10 CFU reduction with E. coli when exposed for
up to 360 sec to plasma.
 while the same exposure time was required for 5 log10
CFU reduction killing with S. aureus samples.
 Pseudomonas aeruginosa cell suspensions where there
was a very few reduction in number of survivals (≤ 10%
of the whole population) after the same exposure time
application.

40. Atmospheric cold plasma has proven sterilization (kill) capability
against both gram-positive and gram-negative bacteria in different
extents depending on special strain characteristics.

41. CASE STUDY OF ALMOND
 Deng et. al., 2006.
 Salmonella spp. Inoculated onto
almonds, reported a reduction of more
than 4 log CFU/ml.
 In this study sterilization was achieved
by placing the almonds in a 10-mm gap
between two plasma discharge
electrodes and treating for 30 s.

42. STERILIZATION OF PACKAGING MATERIALS
 Muranyi et. al., (2007) cold plasma sterilization allows fast and
safe sterilization of packaging materials such as plastic bottles, lids
and films without adversely affecting the properties of the material
or leaving any residues.

43. CONT..
 Muranyi et. al. (2007)
 Polyethylene terpthalate (PET)

44. IN‐PACK DECONTAMINATION
 Schwabedissen, A. et. al., 2007.
 A 4 log reduction of B. subtilis spores was achieved for 10 min
exposure to the plasma species
 The treatment of tomatoes demonstrated no mildew growth
after 14 days.
 Extension of shelf life of strawberries

45. IN‐PACK DECONTAMINATION OF FOOD PRODUCTS
 EU funded project –SAFE‐BAG
 E. coli
 Exposure time 20-45 s
 PP, LDPE
 http://www.safebag-fp7.eu/

46. CONTROL OF BIOFILMS AND DECONTAMINATION OF PROCESSING
SURFACES
 Biofilms are problematic in particular food industry sectors such as
brewing, dairy processing, fresh produce, poultry processing and
red meat processing.
 Vleugels et al.(2005) successfully inactivated biofilms forming
Pantoea agglomerans grown on synthetic membranes by 2 orders
of log reduction in 10 min.
 Abramzon et al. (2006) have reported almost 100% kill of
Chromobacterium violaceum cells embedded in a 4-day old
biofilms.
 Deng et al.(2006) showed that cold gas plasma has the potential to
denaturize proteins attached to stainless steel.

47. MICROBIAL INACTIVATION USING PLASMA
Microorganism Treatment
medium
Atmosphere Log
reduction
Reference
Bacillus
atrophaeus
PET foils Air 5.1-5.4 Muranyi et al.,
2007
Bacillus pumilus PET foils Air 5.5-5.9 Muranyi et al.,
2007
Bacillus cereus Peptone water
media pH 5-7 on
microscope
slides
Air 2.8-3.9 Kayes et al.,
2007
Salmonella Peptone water Air ~7 Fernández &
Thompson,
2012
Listeria
monocytogenes
peptone media
pH 5-7 on
microscope
slides
Air 2.1 - >4.5 Kayes et al.,
2007

48. CONT..
Microorganism Treatment
medium
Atmosphere Log
reduction
Reference
Staphylococcus
aureus
PET foils Air >6.9 Muranyi et al.,
2007
Escherichia coli PET foils Air 5.6- 6.4 Muranyi et al.,
2007
Escherichia coli Polyethylene
strpis
Argon >3.8 Brandenburg
et al., 2007
Escherichia coli Raw almonds Air 5.0 Deng et al.,
2007
Salmonella Mons PET foils Air >6.7 Muranyi et al.,
2007
Aspergillus niger PET foils Air 3.0-3.6 Muranyi et al.,
2007
Saccharomyces
cerevisiae
Nitrocellulose
membrane
Helium /
oxygen
>5.1 Lee et al., 2006

49. OTHER USES OF PLASMA
 Dental treatment
 Wound healing
 Coating of material
 In automobiles
 Space research
 Lighting purposes
 Pollution control

50. ADVANTAGES
 Eecontamination of products
 Highly cost-effective
 Environmental and economically
beneficial.
 Pollution control applications
 Reliable and user-friendly
 Mild surface decontamination
technology for products such as cut
vegetables and fresh meat
 Disinfect surfaces before packaging
or included as part of the packaging
process

51.  Cold plasma are the relatively early state of technology development
 Important aspects of this technology are still immature
 Optimization and scale up to commercial treatment levels require a
more complete understanding of these chemical processes.
 High investment
 Variety and complexity of the necessary equipment
 Antimicrobial modes of action for various cold plasma systems vary
depending on the type of cold plasma generated.
Limitations

52. FUTURE RESEARCH
 Further optimization and technology
development to determine the
antimicrobial efficacy
 Characterization of the antimicrobial
compounds
 Detailed examinations of the sensory
properties of cold plasma treated
produce
 More information on the economics of
the process using larger scale
equipment.

53. CONCLUSION
 Emerging non-thermal technology.
 Microbial destruction and surface modification of substrate
 High efficacy, preservation and does not introduce toxicity to the
medium.
 Effective at ambient temperatures
 No or minimum thermal effects on nutritional and sensory quality
parameters of food with no chemical residues.

54. REFERENCES
 Deng X, Shi J, Kong MG (2006) Physical mechanisms of inactivation of
Bacillus subtilis spores using cold atmospheric plasmas. Plasma Sci
IEEE Trans 34(4):1310–1316
 Dirks, B. P., Dobrynin, D., Fridman, G., Mukhn, Y., Fridman, A. and
Quinlan, J. J. 2012. Treatment of raw poultry with nonthermal dielectric
barrier discharge plasma to reduce campylobacter jejuni and salmonella
enterica. Journal of Food Protection. 75 (1): 22–28.
 E. Timmermans. 1999. Atomic and molecular excitation processes in
microwave induced plasmas, Ph.D. Thesis, Eindhoven University of
Technology.
 Kalyani, N., Anderson, N. M., Fleishman, J. G. and Keller, S. 2012.
Inactivation of salmonella enteritidis PT 30 on almonds with a fluidized
bed atmospheric pressure plasma, FDACFSAN, 23: 233-41.
 Muranyi P, Wunderlich J, Heise M (2007) Sterilization efficiency of a
cascaded dielectric barrier discharge. J Appl Microbiol 103(5):1535–
1544

55. REFERENCES
 Lerouge, S., Wertheimer, M. R., Yahia, L’H. Plasma Sterilization: A
Review of Parameters, Mechanisms, and Limitations. Plenum
Publishing Company. September 17, 2001.
 Muranyi P, Wunderlich J, Heise M (2007) Sterilization efficiency of a
cascaded dielectric barrier discharge. J Appl Microbiol 103(5):1535–
1544
 Nehra, V. Kumar, A. and Dwivedi, H. 2008. Atmospheric non-thermal
plasma sources, International Journal of Engineering, 2(1): 53-68.
 Niemira, B.A. 2012. Cold plasma decontamination of foods, Annual
Review of Food Science and Technology, 3:125-42.
 Sasai, Y., Kondo, S., Yamauchi, Y. and Kuzuya, M. 2011. Cold
plasma techniques for pharmaceutical and biomedical engineering.
In: Laskovski, A. (eds.). Biomedical Engineering, Trends in Materials
Science, InTech Europe, pp: 101-22.

56. Thank you For Your Kind
attention