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MICROWAVE AND RADIO FREQUENCY PROCESSING GUIDE
- 1. MICROWAVE AND RADIO FREQUENCY PROCESSING Guided By: Dr. Anil Kumar Sir. Submitted By: Bijjam Madhavi MSc. Food Technology
- 2. FOOD PROCESSING… • A simple definition of food processing is the conversion of raw materials or ingredients into a consumer food product. • Commercial food processing “ is defined as that branch of manufacturing that starts with raw vegetable, animal or marine materials and transforms them into intermediate food stuffs or edible products through the application of labour, machinery, energy and scientific knowledge”.
- 3. MICROWAVE PROCESSING… Microwaves are the shortest wave length region of the spectrum and a part of the electromagnetic spectrum. Electromagnetic waves frequencies range from 300MHz – 300GHz or wavelengths in air ranging 100cm – 1mm.
- 4. PROPERTIES OF MICROWAVE… Electromagnetic radiation of short wavelength. Reflected by conducting Not reflected by ionosphere.
- 5. MICROWAVE OVEN… A microwave is a appliance that cooks heat food by dielectric heating. It is accomplished by using microwave radiation to heat and other polarized molecules in the food.
- 7. PARTS OF EQUIPMENT: Temperatur e Indicator Door Cooking Cavity Turntable Magnetron Oven Cavity Wave Guide Stirrer Power Cord
- 9. MICROWAVE GENERATION… The microwaves are generatd by special oscillator tubes called “magnetrons” . These are devices that convert low frequency electrical energy into hundrends and thousands of megacycles. The electromagnetic energy, at microwave frequency is conducted through a coxial tube or waveguide at a point of usage. Magnetron: It is a cylindrical diode with a ring of resonant resonant cavities that acts as a anode structure. The cavity is the space in the tube which becomes excited in a way that makes at a source for the oscillation of microwave energy. The magnetron is a vacuum valve in which the electron, emitted by the cathode, turn around under the action of a continuous electric field produced by the power supply and of a continuous magnetic field. The movement produces the electromagnetic radiation.
- 10. ADVANTAGES AND APPLICATIONS… Speedy Clean Smell free Less washing up Thawing Nutritionally sound Easy to use Cool
- 11. DISADVANTAGES… Because of speed, and the way in which microwave energy cooks, food cooked in a microwave oven will not be brown, so no crust formation. High initial cost. Short cooking time does not allow flavours to develop and this makes food unacceptable.
- 12. RADIO FREQUENCY… Radio frequency is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20KHz to around 3000GHz. Radio frequency heating is the electrical energy is firstly converted to electromagnetic radiation which subsequently generates the heat with in the product.
- 13. PRINCIPLE OF RADIO FREQUENCY… RF heating is a combination of dipole heating and electric resistance heating resulting from the movement of dissolved ions present in the food. RF with the electromagnetic waves in 30-3000MHz spectrum added advantage of uniform heating in homogenous foods, high penetration depth used to pasteurize or sterilize liquid products. The mechanism of RF heating is that the molecules within a product placed in an RF environment reorient themselves continuously in response to the applied field. This response initiates the volumetric heating with in the entire product due to frictional interaction between the molecules, thus selectively heats only the product and not the air or equipment surrounding it.
- 15. RF HEATING OF PARTICLES…
- 16. RF HEATING MECHANISM… In radio frequency heating system, the RF generator creates an alternating electric field between two electrodes. The material to be heated is placed in between the electrodes where the alternating energy causes polarization of the molecules, thus continuously reorient themselves to face opposite poles. The energy absorption involves: Primary two two mechanisms – dipolar relaxation and ionic conduction Water in the food is often the primary component responsible for dielectric heating. Due to their dipolar nature, water molecules try to follow the electric field associated with electromagnetic radiation as it oscillates at very high frequencies, thus producing heat.
- 17. CONT…. Secondary mechanism of heating is through the oscillatory migration of ions in the food that generates heat. The amount of heat generated in the product is determined by : (a)frequency, (b)the square of the applied voltage, (c) dimensions of the product and (d) the dielectric loss factor of the material. RF power is produced when electricity is applied to an RF generator whose signal is amplified and delivered to a parallel electrode system, in which selected material is placed.
- 20. ADVANTAGES… High energy transfer efficiency. Uniform heating with in the product. Short process time. Reduced equipment dimension. Instant and accurate process control. Better preservation of sensorial, chemical and physical characteristic s of the product.
- 21. DISADVANTAGES… The cost of electronic components used in this technique is quite high. Energy consumption is higher. Different products will require different heating process time due to their shape, size, dielectric material, position etc…
- 22. CONCLUSION… • MICROWAVE FREQUENCY Microwave cooking range is soon taking up a key role as one of the daily use home appliances in Indian homes. Available in almost all electronic shops, they are becoming essential for the working families in India. The price of microwave oven is less. • RADIO FREQUENCY The industrial application of RF is still limited towards meat, disinfectant of agricultural commodities and post baking. RF power provides a greater 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.
- 23. • REFERENCES: Brittany, H. Microwave synthesis. Matthews, chemistry at the speed light. Microwave energy and its in food nindustry by Adarsh M. Youn KS , Radio frequency Zhang, L. , Quality of radio heated. Wang J, Radio frequency heating heterogeneous food.