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Non thermal food preservation methods with special reference

to ohmic heating

H.M.D.N. HerathAG/2011/3113

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Content

• Food preservation classification • What is ohmic heating? • Important benefits • Ohmic heating processing step• Applications• Advantages to ohmic systems• Disadvantages to Ohmic Systems• Summary

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Food preservation methods

Thermal preservation

Heating processing

Cold processing

Non thermal preservation

Irradiation

Ohmic heating

Ozonation

High pressure processing

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What is ohmic heating?

• Ohmic heating is an advanced terminal processing method where in the food material which serves as an electrical resistor, is heated by passing electricity through Which result in rapid & uniform heating

• Electrical resistance heating or joule heating or electro-heating

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History• The concept of ohmic heating of foods is not new

• In the nineteenth century, several processes were patented that used electrical current for heating flowable materials

• Within the past two decades, new and improved materials and designs for ohmic heating have become available. The Electricity Council of Great Britain has patented a continuous-flow ohmic heater and licensed the technology to APV Baker

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Important benefits

1. Fast Processing

2. Homogeneous Treatment

3. Compactness of an Ohmic Installation

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Ohmic heating processing step

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Applications• Sensitive Products egg products,

processed fruits,

• Fouling Products sauces, creams, cream cheese, viscous materials

• Value-Added Products

Ohmic processed commercial available products

• .

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Advantages • Heating food materials by internal heat

generation– Conventional heat transfer has limited dielectric

penetration

– Heating takes place volumetrically and the product does not experience a large temperature gradient within itself as it heats

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Advantages cont..

– Reducing risks of fouling on heat transfer surface and burning of the food products

– It results in minimal mechanical damage and better nutrients and vitamin retention.

– High energy efficiency because 90% of the electrical energy is converted into heat

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Advantages cont.

• Optimization of capital investment and product safety as a result of high solids loading capacity.

• Ease of process control with instant switch-on and shut-down.

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Advantages cont.

• Reducing maintenance cost (no moving parts).

• Ambient-temperature storage and distribution when combined with an aseptic filling system.

• A quiet environmentally friendly system.

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Disadvantages to Ohmic Systems

• High installation cost

• Can not apply for all the food

• Increased electrical conductivity of food materials

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Summary

• Ohmic heating system can be consider has a better in all over the world .

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Reference • (De Alwis and Fryer 1990) De Alwis, A. and P. Fryer (1990). "The use of direct resistance heating in the food

industry." Journal of Food Engineering 11(1): 3-27.• (Halden, De Alwis et al. 1990, Icier and Ilicali 2005) Halden, K., et al. (1990). "Changes in the electrical conductivity of foods during

ohmic heating." International Journal of Food Science & Technology 25(1): 9-25.

• (Icier and Ilicali 2005) Icier, F. and C. Ilicali (2005). "Temperature dependent electrical conductivities of

fruit purees during ohmic heating." Food Research International 38(10): 1135-1142.

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THANK YOU