1. What is ohmic heating
Ohmic heating is an advanced thermal processing
method wherein the food material, which serves
as an electrical resistor, is heated by passing
electricity through it.
Electrical energy is dissipated into heat, which
results in rapid and uniform heating.
Ohmic heating is also called electrical resistance
heating, Joule heating, or electro-heating, and
may be used for a variety of applications in the
food industry
2. How is ohmic heating different from
conventional thermal processing
During conventional thermal processing, either in
cans or aseptic processing systems for particulate
foods, significant product quality damage may occur
due to slow conduction and convection heat transfer.
ohmic heating volumetrically heats the entire mass of
the food material, thus the resulting product is of far
greater quality than its canned counterpart.
3. How is ohmic heating different from
conventional thermal processing
It is possible to process large particulate foods
(up to 1 inch) that would be difficult to process
using conventional heat exchangers.
ohmic heater cleaning requirements are
comparatively less than those of traditional heat
exchangers due to reduced product fouling on
the food contact surface.
4. Products suitable for ohmic heating
Ohmic heating can be used for heating liquid foods
containing large particulates, such as soups, stews, and
fruit slices in syrups and sauces, and heat sensitive liquids
The technology is useful for the treatment of
proteinaceous foods, which tend to denature and
coagulate when thermally processed.
liquid egg can be ohmically heated in a fraction of a
second without coagulating it.
5. Products suitable for ohmic heating
Juices can be treated to inactivate enzymes
without affecting the flavor.
Other potential applications of ohmic heating
include blanching, thawing, on-line detection
of starch gelatinization, fermentation, peeling,
dehydration, and extraction.
6. Microorganisms inactivation by ohmic
heating
Like thermal processing, ohmic heating inactivates microorganisms by
heat
Also non-thermal electroporation type effects have been reported at
low-frequency (50�60 Hz), when electrical charges can build up and
form pores across microbial cells, however, it is not necessary to
claim such effects since heating is the main mechanism.
Electroporation is a significant increase in the electrical conductivity
and permeability of the cell plasma membrane caused by an
externally applied electrical field
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. ohmically processed commercial products
available on the market
A number of processing plants currently
produce sliced, diced, and whole fruit within
sauces in various countries, including Italy,
Greece, France, Mexico, and Japan.
In the United States, ohmic heating has been
used to produce a low-acid particulate product
in a can, as well as pasteurized liquid egg.
9. ohmic heating environmentally friendly
This process uses ordinary electricity. No emissions are produced
at the point of use.
One emerging application of ohmic heating is fruit peeling, which
may greatly reduce the use of lye that is common to such
operations, and results in environmental benefits.
Lye is a corrosive alkaline substance, commonly sodium hydroxide
Lye is valued for its use in food preparation, soap making, and
household uses, such as oven cleaner and drain opener.
