Cold plasma processing uses ionized gases produced by non-thermal techniques to sterilize and extend the shelf life of foods. Plasma is ionized gas consisting of electrons, ions, and molecules that can be produced through techniques like corona discharge or dielectric barrier discharge. Cold plasma is effective at reducing microbes like bacteria and fungi on foods while minimally impacting quality. It has shown potential for use in industries like cereal, meat, fruit/vegetables, spices, dairy, and food packaging. Research institutes are further exploring cold plasma processing for food safety and quality.

1. COLD PLASMA PROCESSING

2. What Is Cold Plasma
- Application on ionized gas produced by non-
thermal techniques on food to impart its
sterilizing and shelf life enhancing properties.

3. What is Plasma ?
• Plasma is an ionized
gas consisting of free
electrons, ions,
reactive atoms, neutral
molecules and photons
• A plasma is a very good
conductor of electricity
and is affected by
magnetic fields.
• Plasmas, like gases
have an indefinite
shape and an indefinite
volume.

4. Classification of plasma
• Thermal
• Non-thermal(cold)
Temperature
• Low pressure
• Atmospheric pressure
• High pressure
Pressure
• Microwave
• Radio frequency
• Corona
• Dielectric barrier Discharge
Mode
• Air
• Oxygen
• Helium
• Argon
Gas

5. Some facts about plasma
sterilization of foods

6. Some facts about plasma
sterilization
• In 1960’s for the first time sterilization property of plasma was introduced,
and a patent was filed in the year 1968
• Destruction of 10^6 spores in inner surface of vials occurred in less than
second using argon plasma by pulsed RF field atmospheric plasma.
• Boucher, and Bithell reported that electrical discharge in particular gases
can lead to complete sterilization
• Plasma can penetrate upto 10 micrometer, 10 times deeper than UV rays,
which is helpful for the destruction of sporulated bacteria

7. • Nelson and Berger reported that O2 plasma showed efficient
biocidal action on B. subtilis and Clostridium sporogenes as
these two were considered as the most resistant bacteria
• Plasmas generated at 200 W were sufficient to reduce the
population of B. subtilis more than 3.5 log10 in 5 min. From
then the utilization of plasma for sterilization was
commercialized

8. How cold plasmas are produced?

9. Corona Discharge
• characteristic of an
asymmetric electrode pair and
results from the electric field.
• Gas is passed through point
discharge where electric field
is very strong resulting into
formation of ions.
• This spreads out towards
planar electrode.

10. Radio Frequency(RF)
• It consists of two concentric
electrodes through which a
mixture of helium, oxygen or
other gases flows
• Inner electrode is coupled to
13.56 MHz radio
frequency power at a voltage
between 100-250 V
• These energetic electrons
undergo inelastic collisions
with the feed gas, producing
excited state molecules,
atoms, free radicals and
additional ion electron pairs

11. Dielectric barrier discharge
• DBD is the electrical discharge between two electrodes
separated by an insulating dielectric barrier.
• Originally called silent (inaudible) discharge and also known as
ozone production discharge.
• It was first reported by Ernst Werner von Siemens in 1857.
• operate at approximately atmospheric pressure (typically 0.1–1
atm). An A.C. voltage with amplitude of 1–100 kV and a
frequency of a few Hz to MHz is applied to the discharge

12. Construction of DBD
• Two electrodes
• Dielectric barrier
near electrodes
• A gas flow
• Ac power supply

15. Advantages of Cold Plasma
• The most attractive features of plasma are their low temperature
property, and high efficiency
• Increases shelf life without affecting sensory qualities
• Very less nutrient loss as compared to other heat treatments
• No chemical treatment required
• Very less time required for treatment

16. Applications of cold plasma Proceessing

17. 1. Cereal Industry
• This technology offers various benefits in cereal industry in addition to the
decontamination.
• 1. Plasma processing is used to modify the properties of brown rice:-
Sarangapani et al. (2015) studied the effect on cooking and textural
properties of parboiled rice under various treatment time and power.
- It increased the water uptake ratio of parboiled rice and also reduced the
cooking time up to 8 min.
- Textural properties were improved after treatment as
hardness and stickiness decreased with increase in power and
time.

18. Chen et al. (2012) used the low-pressure plasma to modify
the microstructure, cooking, and textural properties of brown
rice
- Treatment results in an etching of brown rice surface, which
allows water to be easily absorbed by the rice kernel during
soaking
- cooking time of brown rice is reduced, and the cooked brown
rice has a soft texture and is easier to chew

20. 2. N.N. Misra et al.(2014) studied ACP
treatment of wheat flour(Hard & soft)
• Samples of 250gm were placed in commercial 270 mm thick polyethylene
terephthalate trays, sealed with a high barrier 50 mm films.
• The atmospheric air condition at the time of treatment was
45 ± 1% relative humidity (RH) and 20 ± 2 ˚C.
• Discrete voltages of 60 and 70 kV were applied across the electrodes for 5 and
10 min
• The rheological properties of flours revealed an improvement in the dough
strength and optimum mixing time for both strong and weak wheat flours
• The elastic and viscous moduli of strong wheat flour progressively increased
with applied voltage and treatment time

21. • Average values of
elastic modulus (G’)
and viscous modulus
(G’’) for the dough
from untreated and
ACP treated flours are
shown in Table
• The G’ of the dough
from all the flours was
greater than G’’,
indicating a
predominance of
anelastic soft solid
nature for the dough

22. 3) The Effect of Plasma on Fungus Colonization of
Wheat Grain and Seed Quality
• Leszek Kordas et al. (2014) :-
-Conducted The assessment of both the effectiveness of spore
destruction and of seed quality under 3-, 10-, and 30-second
exposures.
- The voltage was set at 8 kV.
- 200 seeds were selected from each variant of the
experiment

23. - Exposure of winter wheat grain to low temperature plasma
resulted in the reduction of the number of colonies of fungi
forming on grain in the optimum time of 10 seconds.
- The results also showed a positive effect of the use of cold
plasma on the basic values determining seed lot quality.

25. 2. Meat and Poultry Industry
• The various food safety intervention technologies-slaughtering,
meat product fabrication (e.g., cutting, blending, and
extruding), processing (e.g., cooking, curing, drying, and
freezing), packaging and also utilize intervention technologies
to ensure a sanitary manufacturing environment.
• Plasma processing offers a wide selection of gas compositions,
generation methods, and methods of product exposure

26. 1) Atmospheric pressure plasma treatment on
ready-to-eat by (Rod et al. 2012).
• The inoculated meat samples in bags containing 30 % oxygen
and 70 % argon were placed between electrodes’
• Treated at 15.5, 31 and 62 W for 2 to 60 s.
• Highest inactivation rates = 1.5 to 1.6 log cfu/gm for 20 s
treatment time interval of 10 min at operating powers of 15.5
and 62 W.
• Surface color changes included loss of redness of 40 and
70 % after 1 and 14 days of storage, respectively, regardless
of plasma treatment

27. 3. Fruit and Vegetable Industry
• Promising technology used in fruit and vegetable processing
industry since last decade to improve the quality of produce
• Capable of reducing microbial populations on produce
surfaces.

28. 1) In-package atmospheric pressure cold plasma
treatment of strawberries N.N. Misra et al.(2013)

29. • Strawberries were treated (ACP),generated with a 60 kV power
pulsed at 50 Hz, across a 40 mm electrode gap, generated inside a
sealed package containing ambient air (42% relative humidity)
• Aerobic mesophillic bacteria, yeast and mould were reduced by 2
log10 within 24 hours pf post-ACP of 5 min
• The respiration rate of produce after treatment showed no
significant difference
• Also, colour and firmness changes were insignificant.

31. 2) Tomato peroxidase inactivation by atmospheric pressure
cold plasma based on DBD S.K. Pankaj et al.( 2013)
• The kinetics of inactivation of tomato peroxidase as a model
enzyme was studied at 30, 40 and 50 kV, for up to 5˚ of
atmospheric air dielectric barrier discharge plasma
treatments

32. • Treatment conditions
were found to influence
the inactivation rates and
the shape of the
inactivation curve.
• The results from this
study indicate that cold
plasma can inactivate
enzymes, in addition to
the reported studies on
microbial
inactivation.

33. 3) Effect of atmospheric pressure cold plasma (APCP) on the
inactivation of Escherichia coli in fresh produce Daniela
Bermúdez et al.(2013)
• Experiment was carried out on three produces namely lettuce,
baby carrot and tomatoes
• Tested voltages were from 3.95 kV up to 12.83 kV at 60 Hz with
processing times from 30 s up to 10 min and The argon flow
rate was 455.33 sccm.
• Samples were placed on sterile petri dishes in the plasma
treatment chamber on top of the stage (about 2 cm from the
mesh)

34. - 1.6 log cfu/g. was the average rate of inactication at highest power and for
longest time
-Tomatoes, followed by lettuce, were easier to disinfect than carrots, maybe
because of the surface structure.
-Color parameters did not show significant changes after processing.
However, the structure of E. coli cells showed a totally damaged surface

35. 4. Spice Industry
• Plasma processing also used for decontamination of spices
and showing the promising results.
• However, indirect application of ACP is preferred over direct
ACP

36. 5. Dairy Industry
• Current thermal decontamination methods are known to
induce changes to the chemical and physiological composition
of milk and milk products.
• Due to its complex structure, milk has so far shown to be
highly sensitive to many current novel technologies
• Using the advantages of cold plasma, this system was tested
for its ability to decontaminate milk and milk products

37. 1) Low temperature plasma for decontamination of E.
coli in milk. Guro et al.(2012)
• Infectious diseases caused by the ingestion of pathogenic
bacteria in contaminated milk are still a major health concern
• The time dependent effect of atmospheric corona discharge
generated with 9 kV of AC power supply on E. coli ATCC 25922
dispersed in whole, semi skimmed and skimmed milk was
examined.
• Plasma was applied at time intervals of 0, 3, 6, 9,12, 15 and
20 min
• A significant 54% reduction in the population of E. coli cells
after only 3 min was observed regardless of the fat content of
the milk.

38. • The initial pre-plasma bacterial count = 7.78 Log CFU/ml
• The final pre-plasma bacterial count = 3.63 Log CFU/ml
• No viable cells were detected after one week examination in whole
milk samples and remained so over the 6 week storage period.

39. 5. Packaging Industry
• Food packaging materials are aimed at serving the functions of
both preserving food and protecting it from deterioration and
outside contamination.
• When not stored in proper conditions, packaging materials can
get contaminated with microorganisms.
• Plasma-treated material provides tremendous advantages to a
package.

40. 1) remove all unwanted organic contaminants
2) Surface treating, or activating a material to
gain an increased wettability quality,
3) The deposition of substrates onto a material, adding desired
new qualities.

41. • It was originally developed to increase the surface energy of
polymers, enhancing adhesion and printability.
• New trends aim to develop in package decontamination,
offering non-thermal treatment of foods post packaging.
• Surface treatments of packaging can serve various purposes
including surface functionalisation, surface cleaning or
etching, and surface deposition.

42. • The properties which can be controlled by using ACP on
packaging materials are:- Contact angle
- Roughness
- Crystallinity
- Wettability

43. INSTITUTES AND INDUSTRIES PROMOTING COLD
PLASMA PROCESSING
1) Wageningen University and Research Centre ,University in
Wageningen, Netherlands
Focused work on:- a) Disinfection of packaging materials
b) Disinfection of food products
2) Campden BRI, U.K. in collaboration with the University of
Liverpool

44. Comparison among PEF, ACP AND HPP
ACP
• Electric impulses can
be applied
homogeneously
through the product
with strong
intensities
• Preservation of liquid
media
• Permeabilisation of
plant and animal
tissue
• Shelf life
improvement
• Microbial safety
PEF
• Uses cold gases to
disinfect the surfaces
of packaging or food
products(by making
ions of gases).
• Disinfection of
packaging materials
• Disinfection of food
products
• Shelf life
enhancement
HPP
• Under these high
pressures(up to 1000
MPa) macromolecules
are altered
• High pressure
pasteurisation
• High pressure
sterilisation
• High pressure product
modification
• Very high pressure
kills only pathogens

45. References
• Niemira, B.A., 2012. Cold plasma decontamination of foods. Annual Review
of Food Science and Technology 3 (1), 125–142.
• Scholtz, V., Pazlarová, J., Soušková, H., Khun, J., & Julák, J. (2015).
Nonthermal plasma—a tool for decontamination and disinfection.
Biotechnology Advances, 33, 1108–1119.
• Poutanen, K., Sozer, N., & Della Valle, G. (2014). How can technology help
to deliver more of grain in cereal foods for a healthy diet Journal of Cereal
Science, 59, 327–336
• Hertwig, C., Reineke, K., Ehlbeck, J., Erdoğdu, B., Rauh, C., & Schlüter, O.
(2015a). Impact of remote plasma treatment on natural microbial load and
quality parameters of selected herbs and spices. Journal of Food Engineering,
167, 12–17.
• Bermudez-Aguirre, D., Wemlinger, E., Pedrow, P., Barbosa-Canovas, G., &
Garcia-Perez, M. (2013). Effect of atmospheric pressure cold plasma (APCP)
on the inactivation of Escherichia coli in fresh produce. Food Control, 34,
149–157.

46. • Misra, N.N., Kadam, S.U., Pankaj, S.K., 2011a. An overview of
nonthermal technologies in food processing. Indian Food Industry 30
(5–6), 45–52.
• Perni, S., Shama, G., Kong, M.G., 2008. Cold atmospheric plasma
disinfection of cut fruit surfaces contaminated with migrating
microorganisms. Journal of Food Protection 71 (8), 1619–1625
• Critzer, F., Kelly-Wintenberg, K., South, S., Golden, D., 2007.
Atmospheric plasma inactivation of foodborne pathogens on fresh
produce surfaces. Journal of Food Protection 70 (10), 2290
• Wang, R. X., Nian, W. F., Wu, H. Y., Feng, H. Q., Zhang, K., Zhang,
J., et al. (2013). Atmospheric-pressure cold plasma treatment of
contaminated fresh fruit and vegetable slices: inactivation and
physiochemical properties evaluation. The European Physical Journal
D-Atomic, Molecular, Optical and Plasma Physics, 66, 1e7.
• Gurol, C., Ekinci, F. Y., Aslan, N., & Korachi, M. (2012). Low
temperature plasma for decontamination of E. coli in milk.
International Journal of Food Microbiology, 157, 1–5.

47. • Segat, A., Misra, N. N., Cullen, P. J., & Innocente, N. (2015). Atmospheric pressure
cold plasma (ACP) treatment of whey protein isolate model solution. Innovative
Food Science and Emerging Technologies, 29, 247–254.
• Todd, E. C. D., & Notermans, S. (2011). Surveillance of listeriosis and its causative
pathogen, Listeria monocytogenes. Food Control, 22, 1484–1490.
• Tiozzo, B., Mari, S., Magaudda, P., Arzenton, V., Capozza, D., Neresini, F., &
Ravarotto, L. (2011). Development and evaluation of a riskcommunication
campaign on salmonellosis. Food Control, 22, 109– 117
• CZAPKA T., KACPRZYK R., KORDAS L., PUSZ W. The influence of the non
thermal plasma on the biological properties of the seed-grain. Electrical Review,
11/b, 222, 2012B
• ie, P., Pu, H., Zhang, B., Su, J., Chen, L., & Li, X. (2015). Structural characteristics
and rheological properties of plasma-treated starch. Innovative Food Science and
Emerging Technologies. doi:10.1016/ j.ifset.2015.11.019.
• Chen, H.H., Chen, Y., & Chang, C.H. (2012). Evaluation of physicochemical
properties of plasma treated brown rice. Food Chemistry, 135, 74–79

48. • Korachi, M., Ozen, F., Aslan, N., Vannini, L., Guerzoni, M. E., Gottardi, D., &
Ekinci, F. Y. (2015). Biochemical changes to milk following treatment by anovel,
cold atmospheric plasma system. International Dairy Journal, 42, 64–69.
• Thirumdas, R., Sarangapani, C., & Annapure, U. S. (2014). Cold plasma: a novel
non-thermal technology for food processing. Food Biophysics, 10, 1–11.