IR heating in food processing
August 2009
Temperature Measurement
Infrared heating is gaining momentum in food processing because it is fast, energy efficient, contact-free and uniform. It is successfully used in drying, roasting, baking and sterilisation applications, with optimum results sometimes obtained from a combination of convection and IR heating.
Food is primarily heated to enhance taste and to extend shelf life. IR heating is ideal since the radiation is readily absorbed by organic substances and generates heat. Heat transfer is fast and can be achieved over some distance with insignificant losses. The wavelength of IR emission can be varied to achieve different effects: penetration, colour, crust, etc. IR heaters are broadly classified as shortwave (0,78–1,4 micron), medium wave (1,5–3,0 micron) and long wave (3,0–6 micron).
The effect of wavelength
Different food components absorb IR energy better at different wavelengths. Choosing a heater of the appropriate wavelength allows users to selectively heat the required food component. Shortwave IR penetrates deeper whereas the longer wavelengths have a greater effect on surface layers. Water, sugars and proteins absorb infrared heat best at wavelengths between 2,5 and 3,3 micron – medium to long wave IR.
Typical applications include the following:
Drying and dehydration
A combination of IR heating and air convection offers better results than air drying alone. Similar improvements can be obtained by adding IR heating to freeze drying processes.
Drying of fruit and vegetables using this combination has resulted in reduced drying times, improved energy efficiency, reduced air-flow requirements, superior product quality and lower overall cost.
Broiling
Some shellfish are irradiated aggressively with shortwave IR to open them. Subsequently they are broiled in the shell with long wave IR, preserving the aroma and texture. Good results are also obtained when heating potatoes, meat products and fish. Depending on the intensity and wavelength of the IR various surface effects like crusts can be formed.
Roasting
Nuts, cocoa beans and similar products are roasted effectively and fast with IR with superior effects on the outer layers. Very fast throughput can also be achieved when heating pre-baked pizzas on a conveyor system.
Sterilisation
IR heating is used to destroy enzymes and micro-organisms such as spores, yeast and bacteria. A typical example is heating the exposed layer of foods in glass or cans prior to sealing of the container.
unitemp designs and manufactures infrared heating arrays, air heating systems and control panels. Drawing on 30 years’ experience, the company has implemented heating solutions for most of the applications mentioned above.
Further reading:
Is the HVAC market in SA missing the big picture?
Iritron
Temperature Measurement
The South African HVAC market is currently grappling with a pervasive mindset that prioritises lowest cost over value for money and technical excellence. However, this approach overlooks the significant benefits that come with investing in high-quality HVAC solutions.
Read more...
Temperature monitoring in dairies
ifm - South Africa
Temperature Measurement
Milk is a natural product whose processing requires precise temperature settings. The Berchtesgadener Land dairy uses innovative temperature sensors from ifm in key process areas.
Read more...
Measuring temperature, relative humidity and dew point temperature
Senseca
Temperature Measurement
Senseca’s range of passive or active transmitters measures temperature, relative humidity, and dew point temperature.
Read more...
Three ways to conduct thermal inspections
Comtest
Temperature Measurement
There’s no universal solution for all infrared inspections with a Fluke thermal camera, also known as a thermal imager. You need to match your method to the type of equipment you’re inspecting and the level of detail you require.
Read more...
New temperature relative humidity and barometric pressure transmitter
Senseca
Temperature Measurement
ENVIROsense, a new environmental temperature, relative humidity, relative humidity and, optionally, barometric pressure transmitter has been launched by Senseca, a leader in the design and manufacture of monitoring and measurement instrumentation.
Read more...
The role of alarm annunciators in temperature monitoring
Omniflex Remote Monitoring Specialists
Temperature Measurement
Director at alarm annunciator specialist, Omniflex explores the importance of alarm annunciators in temperature monitoring applications, drawing on examples from different industrial settings.
Read more...
Increased safety and control in steel plants
Temperature Measurement
AMETEK Land has helped a major metals industry plant designer to enhance safety, control, and efficiency in steel plants.
Read more...
Industrial water heating solutions
Temperature Measurement
Electrolux (Kwikot) Industrial’s massive water heating tanks are making a name for themselves beyond local borders.
Read more...
Optimising steam management for boiler efficiency
Endress+Hauser South Africa
Temperature Measurement
Endress+Hauser understands the daily challenges and demands placed on energy and utility managers across the spectrum of steam generation, distribution and consumption activities. Its global team is committed to working with its partners to overcome these complexities, and particularly those that aim for a safe, economic and sustainable sitsce of steam energy production and delivery.
Read more...
Temperature to IO-Link module
ifm - South Africa
Temperature Measurement
IO-Link has become established as an intelligent interface for integrating smart sensors and devices in various industries. With the new ifm IO-Link measuring modules, up to four temperature probes can be connected to an IO-Link master port in two-, three- or four-wire configuration.
Read more...
printer friendly version