Ohmic heating


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Ohmic heating

  1. 1. What is ohmic heatingOhmic heating is an advanced thermal processingmethod wherein the food material, which servesas an electrical resistor, is heated by passingelectricity through it. Electrical energy is dissipated into heat, whichresults in rapid and uniform heating.Ohmic heating is also called electrical resistanceheating, Joule heating, or electro-heating, andmay be used for a variety of applications in thefood industry
  2. 2. How is ohmic heating different from conventional thermal processingDuring conventional thermal processing, either incans or aseptic processing systems for particulatefoods, significant product quality damage may occurdue to slow conduction and convection heat transfer.ohmic heating volumetrically heats the entire mass ofthe food material, thus the resulting product is of fargreater quality than its canned counterpart.
  3. 3. How is ohmic heating different from conventional thermal processingIt is possible to process large particulate foods(up to 1 inch) that would be difficult to processusing conventional heat exchangers.ohmic heater cleaning requirements arecomparatively less than those of traditional heatexchangers due to reduced product fouling onthe food contact surface.
  4. 4. Products suitable for ohmic heatingOhmic heating can be used for heating liquid foodscontaining large particulates, such as soups, stews, andfruit slices in syrups and sauces, and heat sensitive liquidsThe technology is useful for the treatment ofproteinaceous foods, which tend to denature andcoagulate when thermally processed.liquid egg can be ohmically heated in a fraction of asecond without coagulating it.
  5. 5. Products suitable for ohmic heatingJuices can be treated to inactivate enzymeswithout affecting the flavor.Other potential applications of ohmic heatinginclude blanching, thawing, on-line detectionof starch gelatinization, fermentation, peeling,dehydration, and extraction.
  6. 6. Microorganisms inactivation by ohmic heatingLike thermal processing, ohmic heating inactivates microorganisms byheatAlso non-thermal electroporation type effects have been reported atlow-frequency (50�60 Hz), when electrical charges can build up andform pores across microbial cells, however, it is not necessary toclaim such effects since heating is the main mechanism.Electroporation is a significant increase in the electrical conductivityand permeability of the cell plasma membrane caused by anexternally applied electrical field
  7. 7. shelf life of an ohmically processed product The shelf life of ohmically processed foods is comparable to that of canned and sterile, aseptically processed products
  8. 8. ohmically processed commercial products available on the marketA number of processing plants currentlyproduce sliced, diced, and whole fruit withinsauces in various countries, including Italy,Greece, France, Mexico, and Japan.In the United States, ohmic heating has beenused to produce a low-acid particulate productin a can, as well as pasteurized liquid egg.
  9. 9. ohmic heating environmentally friendlyThis process uses ordinary electricity. No emissions are producedat the point of use.One emerging application of ohmic heating is fruit peeling, whichmay greatly reduce the use of lye that is common to suchoperations, and results in environmental benefits.Lye is a corrosive alkaline substance, commonly sodium hydroxideLye is valued for its use in food preparation, soap making, andhousehold uses, such as oven cleaner and drain opener.