8: RF Processing

Question 1

Compare between thermal and non-thermal RF processing.

Answer 1

Thermal RF processing uses high intensity RF and heats up food via dielectric heating.

Non-thermal RF processing uses low intensity RF to cause electroporation to inactivate microorganisms at moderate temperatures.

Question 2

What are the components of RF processing equipment?

Answer 2

Electrodes are placed in the sample. AC power supplies high voltage to the electrodes continuously, high electric field is generated.

Question 3

Describe the factors affecting efficiency of RF treatment.

Answer 3

• Geometry and dimension of treatment chamber
• Electric field uniformity
• Electric field strength (Too high = overheating, too low = insufficient MO inactivation)

Question 4

Describe the impact of RF processing to yeast and bacteria.

Answer 4

Yeast: Effect of electric field strength is more prominent over temp.

Bacteria and Spores: Effect of temp is more prominent.

Question 5

What are the strengths and weaknesses of RF processing?

Answer 5

Strengths:
- Inactivate MOs at a short time
- Preserve thermal labile nutrients

Weaknesses:
- High electricity cost.

Question 6

What combine high and low frequencies together in RF processing?

Answer 6

Combination of high electric field and low frequencies provide higher efficiency:
- Low freq, causes reversible and irreversible electroporation
- High freq, requires higher electric field strength to achieve effective inactivation.