COLD PLASMA

INTRODUCTION

Food industry challenges

Consumers expect that the food they consume is safe to eat. In addition,

the consumer also wants the food to have high nutritional value with

minimal preparation times, as evidenced by the growth in products such

as convenience ready-to-eat (RTE) foods and minimally processed fresh

produce. In order to meet these demands, food manufacturers are

looking for new methods and technologies. A new technology which may

meet manufacturers’ needs is cold plasma.

History

The word "PLASMA" was first applied to ionized gas by Dr. Irving

Langmuir, an American chemist and physicist, in 1929.

WHAT IS PLASMA?

Plasma is often called the "Fourth State of Matter," the other three being

solid, liquid and gas.

A plasma is a distinct state of matter containing a significant number of

electrically charged particles, a number sufficient to affect its electrical

properties and behavior.

In an ordinary gas each atom contains an equal number of positive and

negative charges; the positive charges in the nucleus are surrounded by an

equal number of negatively charged electrons, and each atom is electrically

"neutral." A gas becomes a plasma when the addition of heat or other energy

causes a significant number of atoms to release some or all of their electrons.

The remaining parts of those atoms are left with a positive charge, and the

detached negative electrons are free to move about. Those atoms and the

resulting electrically charged gas are said to be "ionized." When enough

atoms are ionized to significantly affect the electrical characteristics of the

gas, it is a plasma

METHODS OF GENERTIING PLASMA

GENARATION OF COLD PLASMA

APPLICATION OF COLD PLASMA IN FOOD INDUSTRY

•Surface decontamination:

Cold plasma can be used for decontamination of products where

micro organisms are externally located. Unlike light (UV

decontamination), plasma flows around objects, ensuring all parts

of the product are treated.

•Mild surface decontamination

For products like cut vegetables & fresh meat, there is no mild

surface decontamination technology available currently; cold

plasma could be used for this purpose.

.

•A plasma torch can be applied to uncooked chicken in an effort to

reduce its pathogen load. After treating the poultry for various times

ranging up to 180 seconds, the plasma entirely or substantially

reduced low levels of bacteria from both skinless chicken & chicken

skin. Even bacteria levels on highly contaminated samples were

significantly lowered.

•Cold plasma use in food packaging technology.

Cold plasma technology is an emerging, green process offering man potential

applications for food packaging.

it was originally developed to increase the surface energy of polymers,

enhancing adhesion ,printability & sealability.

it has recently emerged as a powerful tool for surface decontamination food

packaging materials.

Gas plasma reactions establish efficient inactivation of micro-organisms (bacterial

cells, spores, yeasts and moulds) adhering to polymer surfaces within short

treatment times. Packaging materials such as plastic bottles, lids and films can be

rapidly sterilised using cold plasma, without adversely affecting their bulk

properties or leaving any residues

New trends aim to develop in package decontamination, offering non-thermal

treatment of foods post packaging. (active packaging technique) it ia effective

& quick method to destroy microbes.

Kevin Keener a professor of food science

is developing methods using cold plasma

to kill bacteria on in-package foods

Kevin Keener, looks for new ways to kill

harmful bacteria, such as E.coli and

Salmonella, that contaminate foods and

cause serious illnesses and deaths. His

method uses electricity to generate a

plasma, or ionized gas, from atmospheric

gases inside the food package.

This process creates a wide variety of

bacteria-killing molecules including ozone,

nitrogen oxides, hydrogen peroxide and

others. These molecules only exist for a

few hours and then revert back to the

original atmospheric gas, leaving a

bacteria-free product.

.

Mode of action in decontamination food stuff/packaging material

by cold plasma

At the beginning.The vacuum ultraviolet

(VUV) energy is very effective in the breaking

most organic bonds (i.e., C-H,C-C, C=C, C-O,

and C-N) of surface contaminants. This helps to

break apart high molecular weight contaminants.

A second cleaning action is carried out by the

oxygen species created in the plasma (O2+,

O2-, O3, O, O+, O-, ionised ozone,

metastably-excited oxygen, and free

electrons). These species react with organic

contaminants to form H2O, CO, CO2, and lower

molecular weight hydrocarbons. The resulting

surface is ultraclean/sterilised.

Thus, destruct the microbial cells by

•Disrupting bacteria cell membrane

•Denaturing proteins

•Damaging bacteria DNA

.Mode of action continue…….

pathogens such as

•Salmonella,

•Escherichia coli ,

•Listeria monocytogenes,

•Staphylococcus aureus

can be reduced by greater than 5 logs following treatment with cold plasma.

Depending on the processing conditions, treatment times can range from 120

seconds to as little as 3 seconds Cold plasma, therefore, holds promise as a rapid,

effective non thermal food processing technology

Advantages & limitation of using cold plasma as a novel method

if food industry.

•flexible sanitizing method uses electricity Eg: plasma torch.

•antimicrobial chemical agents are not required to inactivation prcess.

•Cost effective method compared to other chemical & thermal decontamination

methods.

•Less time consuming method.( need few seconds to inactivate microbes within

the food surface & mild surface)

• green technology ( since harmfull effects to environment has not idetified yet)

Key limitations cold plasma are the relatively early state of technology

development, the variety and complexity of the necessary equipment, and the

largely unexplored impacts of cold plasma treatment on the sensory and

nutritional qualities of treated foods.

Also, the antimicrobial modes of action for various cold plasma systems vary

depending on the type of cold plasma generated.Optimization and scale up to

commercial treatment levels require a more complete understanding of these

chemical processes.

Nevertheless, this area of technology shows promise and is the subject of active

research to enhance efficacy.

Applying cold plasma technology to Sri Lankan food industry.

•Adapting the technology for liquids could allow development of

portable devices to clean drinking water in areas with contamination

or that lack other purification methods or it can be used instead of

using chlorination method.

•Also It could allow food processors to bottle juices or dairy industry

without first heating them, a process widely used to kill bacteria that

can alter products which is similar to pasteurization process.(

however without the heat and quality changes that occur with that

process.)

References JOURNALS

•INTERNATIONAL JOURNAL OF EMEGING TRENDS IN ENGINEERING &

DEVLOPMENT

•JOURNAL OF FOOD ENGINEERING www.elsevier.com/locate/jfoodeng

E-BOOKS

•TRENDS IN FOOD SCINECE & TECHNOLOGY BY S.K. Pankaj, C.

Bueno-Ferrer, N.N. Misra, V. Milosavljević, C.P. O’Donnell, P. Bourke,

K.M. Keener, P.J. Cullen

WEBSITES

•http://news.discovery.com/tech/biotechnology/cold-plasma-kills-

bacteria-better-than-antibiotics.htm

•http://www.researchgate.net/publication/258344120_Applications_

of_cold_plasma_technology_in_food_packaging

•https://fstjournal.org/features/28-1/cold-plasma

• http://www.foodqualitynews.com/R-D/Plasma-potential-for-tackling-

strawberry-

•http://rspublication.com/ijeted/may-12/89.pdf