This presentation will cover all about radio frequency heating

1. Master’s Seminar
on
Radio Frequency heating and its application in Food Processing
Swami Vivekanand College of Agricultural Engineering and Technology &
Research Station,IGKV,Raipur
Presented by
Name- Suraj Kumar
Class- M.Tech.(Final year)
Dept. of Agricultural Processing and Food Engineering
College Id.- 220118011
Session 2019-20

2.  Introduction of Radio frequency.
 Principle of Radio frequency heating.
 Radio frequency (RF) heating mechanism.
 Difference between
RF Vs Conventional Heating.
RF Vs Microwave Heating.
 Advantages of using RF in food processing.
 Disadvantages of using RF in food processing.
 Factors affecting RF heating.
 RF Applications in food industry.
 Application of RF on various food based on research work.
Content

3. Radio frequency heating (RFH) is an advanced and emerging
technology for food application.
Radio frequency (RF) is known as high frequency dielectric
heating refer to the heating of dielectric material(water) with
electromagnetic energy at frequency between 1 to 300 MHz.
Radio frequency have Higher penetration power than Microwave.
Prime goal of this novel technology is food preservation by ensuring
its safety and quality.
 Radio Frequency(RF) heating

4. RF heating was first used in 1895 as a medical treatment
method. In food processing, it was first explored for
blanching and then for cooking and dehydrating .
In the 1960s, many attempts were made to use RF to thaw
frozen foods.
In those studies, different frozen food materials were tested
using lab-scale and even industrial-scale (25 kW) RF systems
 History of Radio frequency heating

5.  Molecular reorientation and friction occurs due to continuous
realignment (action of changing different position or state) of the
moleculs.
 Ionic movement towards oppositively charge electrode.
 Due to Rapid change in polarity causes heat generated.
 Principle of Radio frequency heating
Figure:- Space charge and dipolar polarization in an alternating
electric field at radio frequencies.(Orsat and Raghavan, 2005).

6.  In RF heating the food is placed between two capacitor plates or
electrods. It plays the role of a dielectric where a high frequency
alternating electric field is applied.
 The electromagnetic energy transfers directly into the product
therefore it induce volumetric heating due to frictional interaction
between molecules.
 Such field will force polar molecules (water) to constantly
realign(reconstruct) themselves with the electric field.
 This molecular movement is very fast due to the high frequency of
the field. It will cause for the generation of heat within the food by
energy dissipation caused by molecular friction.
 Radio frequency heating mechanism

7.  General Radio frequency heating process

8. RF Food dryer

9.  Conventional heating (i.e. conduction, convection, radiation) has
a heat source on the outside .Heat is transferring to the surface of
the material and then conducting the heat to the middle of the
material.
 Radio Frequency heating is different, it heats at the molecular
level. So it heats from within the material and heats the middle
as well as the surface.
 Radio frequency Vs Conventional heating

10.  Lower frequency(1-300MHz)
and high penetration depth.
 One Directional heating
 Generally 10-15MHz
frequency range used in
industry for food heating.
 RF Penetration depths
At 27.12 MHz- 20cm
 Higher frequency(300 MHz-30
GHz) and low penetration.
 All directional heating.
 Generally 915-2450 MHz
frequency range used in industry
for food heating.
 MW Penetration depths
At 915MHz- 8 to 22cm
At 2450MHz- 3-8 cm
Difference between RF heating and microwave heating
Radio frequency heating Microwave heating

11.  Microwave vs radio frequency heating

12.  Advantages of using RF in food processing
Radio Frequency heating and drying benefits over
conventional heating and drying methods:
 Faster heating and reduces drying times
 More uniform heating and drying
 High efficiency
 Selective heating
 Energy efficiency
 Contactless heating
 Deep penetration heating.
 Avoiding overheating on the surface of the product

13. Equipment and operating cost
• RF heating equipment is more expensive and operating cost is
higher than conventional convection, radiation or steam
heating systems.
• It is also more expensive than an equivalent ohmic heating
system.
 Disadvantages of using RF in food processing

14. Dielectric properties of food materials can be divided into two
parts
A) Permeability
B) Permittivity ( 𝜖)
• Permeability - It shows free space and are not assumed to
contribute to heating.
• Permittivity ( 𝜖) - Reported in terms of dielectric constant( 𝜖′) and
loss factor( 𝜖′′) influences the heating rates.
𝜖 = 𝜖′− j 𝜖′′
 Factors Influencing RF heating
1) Dielectric Properties
(Permittivity)

15. Here,
• 𝜖′ is measure of the polarizing effect from the applied
electric field & also indicates the capacity to absorb,
transmit and reflect energy from the electric portion of the
electrical field.
• j = constant
• 𝜖′′ measures the amount of energy that is lost from the
electrical field related to how the energy from a field is
absorbed and converted to heat.

16.  Dielectric properties also influences by
 Moisture content
 Frequency of applied alternating field
 Temperature and chemical composition of the material
2) Another physical factors also affect the RF heating systems such
as
 Shape of product
 Geometry and
 Product position
.

17.  Application of RF heating in food industry
Drying
Application
Pasteurization
Sterilization
Meat processing
Thawing
Blanching
Heating of bread
Baking

18. 1. Thawing of food products :
• Rapid thawing of meat and seafood products enhancing(improve
quality) the product freshness quality.
• More suitable for industrial heating of meats because RF has greater
penetration depths than Microwave(MW).
2. Pasteurization/sterilization
• There is a demand for more in-package product pasteurization and
sterilization of liquid food( fruit juice )today. As a non-contact (used
in plastic bottle)volumetric heating technique.
3.Baking and Drying
• Drying of food ingredients (e.g. herbs, spices,vegetable)
• Potato products - French fries.
• Number of pasta products.
• The post-baking of biscuits.
• RF drying of grains such as cowpea grains.

19. Process Frequencys,MHzFood items
 Thawing of
frozen food
References
 Tempering
 Roasting
 Post baking
drying
 Previous Successfully application of RF heating for food processing
 Pasteurization
Egg ,fruit, vegetable
Fish ,
Meat
36
14-17
36-40
36-40
27.12Cookies ,crackers ,snake
food
Meat
Meat,
Sausage emulsion
9
27
Cocoa beans 60
Experimental station
Pharma,Italy 1997
Jason and Sanders.,1962
Sanders,1966
Radio frequency Co.MA
mermelstein.,1998
Electrotechnology
application center,PA
Houben et al.,1991
1994

20. 1.Meat and fish product
 RFheating at 27.12MHzand applying an alternating current of 6kW
can be used to process meat and fish processing in industries in large
polymeric containers (295 x 253 x 42 mm3) to retain product quality
better compared to conventional method of heating.
 The RFprocess operated in the 70-90ºC range and with high efficiency
(50%), which compares well with the 10-15% efficiency for
conventional surface heating methods .
 It shown the uniform and deeppenetration of RFwaves resulting in
rapid and homogeneous heating provide greater than 99.999% reduction
in infection levels.
Application of Radio frequency on various food based on
research work

21. 2. Thawing of fruits,vegetable
 Using RF energy for thawing frozen products such as frozen
fruits, vegetables within 2 to 15 min at 14–17 MHz .
 The use of this technology resulted in better quality due to
minimal discoloration(color loss) and loss of flavour when
compared with traditional thawing.

22.  RF treatment on microbial inactivation in orange ,apple juice and
milk was assessed.
 For microbial inactivation and microbial quality of on orange, and
apple juice provides 27.12 MHz with product temperature
maximum of 65˚C at the outlet.
 It is demonstrated that the potential of RF towards the inactivation
of E.Coli K12 (microrganism name) in apple juice, orange juice
respectively is effective than the conventional methods.
 In Milk apply 2 kW electric power and 27.12 MHz RF. it is
demonstrated the best conditions to inactivation of both Listeria
and E. coli cells(microrganism).( Awuah et al. (2005)
3. Beverages product
On orange,apple juice and Milk

23. OnWheatflour
 Theeffectsof theRF heatingon wheatflour,placedin cuboidal
boxes, itsrelativepositionbetweenthe RF electrodesandgiven
frequencyof 27.12MHz.
 Simulatedresultsshowed thattheRF heatinguniformitycouldbe
improvedusinglargersamplesizesplacedintheairbetweenthe
electrodes.
4.Drying in agriculture product

24. 5. Disinfection of agriculture product
On Black and Red pepper spices.
 In Black pepper by RF heating provided 27.12MHz RF for 50 second
resulted in 2.80 to 4.29 log CFU(colony forming unit)/g reductions of S.
Typhimurium and E. coli O157:H7(micro organism name).
 In Red peppers provided 27.12 MHz RF heating for 40 second reduced
pathogens by 3.38 log CFU/g to more than 5 log CFU/g without affecting
the color.
 This report suggested the RF heating has the potential for novel thermal
process to control food borne pathogens in spices.

25. The main problem was in the bakery industry, where there was
a lack of uniformity in the product moisture content.
RF post-baking processes can solve this problem. It was
possible to add an RF drying unit immediately after a
conventional baking oven to increase production and savings
in floor space.
 RF drying provides a more uniform moisture content in final
products and reduces the possibility of mould growth, which
consequently increases the shelf-life of product.
6. Drying and Post -baking

26. The industrial application of RF is still limited towards meat,
disinfection of agricultural commodities and post baking
,where there is large potential source available in utilization
RF heating.
RF power is provide a grater challenge to engineer to
develop large scale production unit for industrial application.
RF heating system can take the modern market on food
processing without any reason of concern.
 Conclusion

27.  Future aspect of radio frequency heating
 In the future, consumer microwaves may also be replaced by
RF units that are much more efficient at cooking or warming
foods.
 The research results with RF-Heating over the past few
decades have clearly shown that in the near future, RF heating
will be a very attractive processing technology to provide safe
and high quality of food products because of its ability to
penetrate deeply with rapid uniform heating without affecting
color and nutrition of food.

28.  Zhang, L., Lyng, J.G., Brunton, N.P., (2004). “Effect of radio frequency cooking on
texture, colour and sensory properties of a large diameter comminuted meat
product”. Meat Science, 68 (2), 257–268.
 Zhang, L., Lyng, J.G., Brunton, N.P., (2006). “Quality of radio frequency heated
pork leg and shoulder ham”. Journal of Food Engineering, 75 (2), 275–287.
 Zhang, L., Lyng, J.G., Brunton, N.P., (2007). “The effect of fat, water and salt on the
thermal and dielectric properties of meat batter and its temperature following
microwave or radio frequency heating”. Journal of Food Engineering, 80 (1), 142–
151.
 Wang, J., Luechapattanaporn, K., Wang, Y., Tang, J., (2012). “Radio- frequency
heating of heterogeneous food – Meat lasagna”. Journal of Food Engineering, 108,
183–193.
 Youn, K.S., Sagong, H, G., Choi, H, S., Ryu, S., Kang, D.H., (2011).“Radio-frequency
heating to inactivate Salmonella Typhimurium and Escherichia coliO157:H7 on
black and red pepper spice”. International Journal of Food Microbiology, 153,171-
175.
Reference