Carmen Bueno-FerrerDublin Institute of Technology

Cold Plasma Processing

1. Dr. P.J. Cullen2. Dr. Paula Bourke3. Dr. Daniela Boehm Microbiology4. Dr. Carmen Bueno-Ferrer Food Packaging5. Dr. Vladimir Milosavljevic Plasma Physics6. Dr. N.N. Misra Food Engineering7. Lu Han Microbiologist8. Dana Ziuzina Microbiologist9. S.K. Pankaj Food Packaging10. Caitlin Heslin Molecular biology11. Apurva Patange Microbiologist12. Chaitanya Sarangapani Food Engineering

S TAT E S O F M AT T E R

SOLID LIQUID GAS PLASMA

Tightly packed, in a regular pattern

Vibrate, but do not move from place to

place

Close together with no regular arrangement.

Vibrate, move about, and slide past each other

Well separated with no regular arrangement.

Vibrate and move freely at high speeds

Has no definite volume or shape and is

composed of electrical charged particles

W h a t i s p l a s m a ?

A plasma is an ionized gas. 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.

Plasma is the common state of matter

S TAT E S O F M AT T E R

W h a t i s p l a s m a ?

•Thermal

•Non-thermal/Cold

Temperature

•Low pressure

•Atmospheric pressure

•High pressure

Pressure

•Air•Oxy

gen•Heli

um•Arg

on…………

Gas

•Microwave

•Radio frequency

•Corona

•Dielectric barrier Discharge

Mode

Ty p e s o f p l a s m a

• Thermal• Non-thermal/ColdTemperature

• Low pressure• Atmospheric pressure• High pressure

Pressure

• Air• Oxygen• Helium• Argon…………

Gas

• Microwave• Radio frequency• Corona• Dielectric barrier Discharge

Mode

Ty p e s o f p l a s m a

The term cold plasma has been recently used as a convenient descriptor to distinguish the one-atmosphere, near room temperature plasma discharges from other plasmas, operating at hundreds or thousands of degrees above ambient

In the context of food processing, a nonthermal plasma (NTP) is specifically an antimicrobial treatment being investigated for application to fruits, vegetables and other foods with fragile surfaces.

C o l d p l a s m a

How can we contain the plasma and increase exposure time?

Put it in a chamber ?

What if one cannot afford a chamber ?

What if one is manufacturing tonnes of product ?

Generate it in a Package

VISION - Develop a technology that can decontaminate products (food, pharmaceuticals, consumer products, etc.) after packaging.

Alexander Fridman – Plasma Chemistry - 2008

In-Package

Shelf-life extension – 4 weeks

Treated Un-treated

220V50Hz

DBD system diagram for in-package meat treatment

Microbia l inacti vati on

Investigation of critical control parameters for inactivation

– Treatment times (60 - 300s)– Mode of exposure (direct/indirect)– Post-treatment storage (0h, 1h, 24h)– Voltage levels (60kV, 70kV, 80kV)– Inducer gases (air, 30%CO2/70%O2, 30%CO2/70%N2)– Biofilm vs. planktonic cells– Media type (PBS, 3% beef extract, 12% beef extract)

Effect of variable voltages

S. aureus E. coli

Microbia l inacti vati on

Effect of inducer gases

0 100 200 3000

2

4

6

CO2/N2, 80 kV

control air, vacuum-packedair, 80 kV

CO2/O2, 80 kV

treatment time [s]

log

10 C

FU

/mL

0 100 200 3000

2

4

6

80 kV

control

70 kV60 kV

treatment time [s]

log

10 C

FU

/mL

0 100 200 3000

2

4

6

8

air, 80 kVCO2/N2, 80 kVCO2/O2, 80 kV

control air, vacuum-packed

treatment time [s]

log

10 C

FU

/mL

0 100 200 3000

2

4

6

8

70 kV80 kV

control60 kV

treatment time [s]

log

10 C

FU

/mL

E.coli ATCC 25922Gram Negative (G-)

Control

Control Treated

L. monocytogenes NCTC 11994Gram Positive (G+)

Treated

Voltage-dependent generation of intracellular ROS

Increase of intracellular ROS with increasing voltage

Microbia l inacti vati on

Meat type

MAP gas

Initial bacterial

load Log10 CFU/g

Reduction day 0

Reduction end of study

Days within

acceptable limits

Current shelf-

life

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

Sliced turkey

CO2/N2 4.94 0.41 61 0.81 84 15-20 21 28-35

Shelf-life study – Effect on background microflora

Food qua l i ty studies

1 3 7 9 10 130.00

5.00

10.00

15.00

20.00

25.00

L-80-5

L-80-1

L-untreated

Days

a* (

arb

itra

ry u

nit

s)

0 1 3 8 10 140.00

2.00

4.00

6.00

8.00

10.00

12.00 P-80-5P-80-1P-untreated

Days

a* (

arb

itra

ry u

nit

s)

0 1 3 8 20 22 24 310

0.5

1

1.5

2

2.5

3

3.5 T-80-5T-80-1T-untreated

Days

a* (

arb

itra

ry u

nit

s)

Colour changesLamb chop

Pork loin Turkey sliced

No significant colour changes in white meats

Food qua l i ty studies – Visual appearanceControl 1 min 2 min 5 min

Day 0

Day 1

Day 7

Day 10

Day 13

Control 1 min 2 min 5 min

Day 0

Day 1

Day 10

Day 14

Food qua l i ty studies – Visual appearance

Food qua l i ty studies – Visual appearance

Control 1 min 2 min 5 min

Day 0

Day 1

Day 20

Day 31

Daza control Daza_80-1 Daza_80-5 ICM control ICM_80-1 ICM_80-50

0.05

0.1

0.15

0.2

0.25

WVT

(g/h

m2)

∙Food packag ing studies

Effect on barrier properties

Water vapour permeabilityVery low values without significant changes were observed for oxygen permeability before and after plasma treatment .

Effect on transparency Before

After

Important remarks

Cold plasma effectively inactivated S. aureus and E. coli in biofilms with major reductions at increasing voltages and increasing oxygen content.

Background microflora studies suggest that plasma treatment can potentially extend the shelf-life of MA-packaged meat products with regards to acceptable levels of microbial content.

Food quality was slightly affected in lamb samples after plasma treatment but no significant changes were observed in pork and turkey meat.

Food packaging materials retained very low barrier properties after plasma treatment and transparency was not affected even after 5 minute treatment.

In-package cold plasma treatment of meat is a novel non-thermal technology for microbial inactivation and shelf-life extension which is also able to retain food quality in white meats.

The industrial partners involved in the project are• Embutidos Daza SL (Spain),

• Food Machinery Company (UK)

• Holfeld Plastics Limited (Ireland)

• Irish Country Meats (Ireland)

• Kamea Electronics SRO (Slovakia)

• Stephens Fresh Foods Ltd (UK)

The RTD providers are• Dublin Institute of Technology (Ireland)

• Innovació i Recerca Industrial i Sostenible (Spain)• Teknologisk Institut – Danish Meat Research Institute (Denmark)

MeatPack Partners

Thank You