1. INTRUDUCTION
• Non-thermal processes such as High pressure processing, Pulse
Electric Field, Ultrasound and Cold Plasma are the emerging trends.
• Potential alternatives for thermal processes.
• Non-thermal processes may over come some of the challenges of
thermal process.
• Cold plasma is one of the non thermal process which can be easily
used across the various sectors including Agri-processing, Food
processing and bio processing.
2. • Matter exist in three state – Solid,liquid, gas
• Heating Solids Liquids Gas.
• What happens when you heat gas?
• Heat gas atoms get ionized ions and electrons this
state of matter is called plasma.
• Plasma is a mixture of positve and negative charges as well as neutral
particles and photons
3. Plasma chemistry
• Ionization – important step in the plasma chemistry
• Plasma chemistry depends on – feed gas composition, humidity,
power, voltage, surrounding phase.
• The ionization of neutral, ground state atoms, molecules, radicles by
electron impact is the most prominent ionization mechanism.
• Chemical composition of air plasma are dominated by oxygen ions,
nitrogen ions.
• When nitrogen in gas phase collide with electrons forms NOx and
oxygen present leads to hydroxyl radicles and ozone
4. Types of plasma
• High temperature plasma - all species ( electrons, ions, and neutral
species ) are in thermal equilibrium state.
• Cold plasma – plasma generated at or near room tempreture.
• Composed of highly reactive species which includes negative and
positive ions, photons, electrons, neutron particles.
• Non uniform distribution of energy among constituent particles.
5. plasma generation: Basic Principle
High voltage (AC/DC electrical discharge, microwave, heat, light,
magneticfield, radio frequency etc)
Feed gas(atmospheric air, pure gas (N2, He, Ar,etc.)or combination of these
gases
Plasma (mixture of gas molecules, atoms, charged ions, free radicles, free
electrons, ozone, elemental oxygen, and photons)
Corona discharge, atmospheric plasma jet, pulsed plasma, nano plasma
6. Working principle of cold plasma
• Sending super speedy electrons through gas. These electrons hit the atoms and
molecules with so much of energy that they pull off the outer most electrons of the
atoms and molecules in the gas creating a mixture of free electrons and free ions.
7. Gasses used in plasma technology
• The gas may be a air or nitrogen or it may be a mixture of gas
containing some proportion of Noble gases such as helium, argon,or
neon.
• The other mixture of gases used or
• The efficiency of operating gas enhanced when oxygen is added to
them.
• Due to the high reactivity of oxygen species they can react with almost
all cell components and contribute for the food quality and microbial
inactivation process.
