What is ohmic heating?
Ohmic heating is an advanced thermal treatment in which food acts as an electrical resistance, and is thus heated by conducting electricity through it. Electrical energy generates to heat, resulting in rapid and uniform heating. Ohmic heating is also called electric resistance heating, Joule heating or electric heating and can be used in a wide range of applications in the food industry.

How is ohmic heating different from conventional thermal treatment?
During conventional thermal treatment, either in canisters or aseptic treatment systems, significant damage to product quality can occur due to slow heat conduction and convection heat transfer. The advantage of ohmic heating is that ohmic heating volumetrically heats the entire food mass, so that the resulting product is of much higher quality than with other methods. It is possible to process foods with large particles (up to 25 mm) that would be difficult to process using conventional heat exchangers. In addition, the cleaning requirements are less than those of the traditional heat exchangers due to reduced soiling on the contact surface between material and product.

What type of products are suitable for ohmic heating?
Ohmic heating can be used to heat liquid foods that contain large particles, such as soups, stews, sliced fruit in syrup, sauces and other heat-sensitive liquids. The technology is useful for treating proteinaceous foods that tend to denature and coagulate when heat treated. For example, liquid eggs can be heated ohmically for a fraction of a second without coagulating. Juice can be processed to inactivate enzymes without affecting the taste. Other possible uses of ohmic heating include blanching, thawing, fermentation, peeling, dehydration and extraction.

What is the durability of ohmic processed products?
The shelf life of ohmic processed foods is comparable to other sterile and aseptically processed products.

Is commercial equipment available?
Emmepiemme, a resident in Italy, supplies commercial-sized equipment. Information on the capacity of commercial equipment depends on the application. Contact Philip Ellegaard Andersen at Alflow Scandinavia on +45 2917 3230 or e-mail pea@alflow.dk.

Are there any ohmic processed commercial products available on the market?
In Denmark, ohmic heating is used in the production of dairy products, including cream cheese. A number of plants around the world produce e.g. soups and fruit. In the United States, ohmic heating has been used to produce a product with large particles and low acidity, as well as pasteurised liquid eggs. In general, any product can be analysed for the possibility of using ohmic heating.

Is ohmic heating environmentally friendly?
Yes, ohmic heating uses only electricity. There is no discharge of waste products at the production site. A future use of ohmic heating is fruit peeling, which can greatly reduce the use of lye and thus protect the environment.

Is ohmic heating approved?
Ohmic heating is approved in accordance with EN1935/2004 and EN10/2011, as well as of course, the CE mark.

Are facilities available for product development before we invest in ohmic heating?
Industrial-scale facilities are available at Emmepiemme. Confidential product evaluations for food safety, quality and durability can be carried out at the test facilities. Emmepiemme and Alflow are also available for guidance on product development. Contact Alflow Scandinavia for further information.