Induction heating in food industry

WHY INDUCTION HEATING IS THE MOST INNOVATIVE OPTION FOR FOOD INDUSTRY?

Induction is an innovative and non-contact electromagnetic heating technology that has several advantages such as high energy efficiency, controlled heating, high safety, and pollution-free. The objective of this article is to build up these and other advantages based on different scientific data about the performance of induction heating in the food industry. We believe that the companies that will apply induction heating in their procedures will have more versatility in sustainable food methods and will be able to face future challenges.

About Induction heating

The induction system (generator + coil) will generate a magnetic field that induces a current in the conductive material (reactor vessel), which will rise in temperature.  Induction heating works only with conductive and ferrous materials. Depending on the material’s magnetic permeability and ferromagnetic properties, various metallic materials, such as steel, cast iron, among others, could be heated by induction.^[1] Non-magnetic conductive materials can also be heated with a lower efficiency.^[2] Induction heating is seen as an ideal technology for pasteurizing liquid foods, and the versatility of induction electric heaters makes it possible to use in various fields of food and beverage industry as is shown in the next image:  

[pic 1]

Induction heating has its advantages over the conventional heating systems (resistance, hot water, gas, steam, etc.) Since it is non-contact it is very efficient, and the heat is generated inside the work-piece (sample) this means direct heating of metal surface without thermal inertia and no conduction loss.^[3] And since induction requires no warm-up or cool-down cycle, make it highly compatible with energy-efficient automated systems. Read the complete article to find out the 5 most important facts about Induction Heating in the food industry.

1. Induction heating improves the quality of the food 

Heat exchangers powered by induction have constant and direct heating to the flowing fluid, with a maximum uncertainty of ± 0.5 ° C ^[4] this avoids local high temperatures and is essential for controlling the reaction kinetics in the food industry.

The experimental result of R. Martel, Y. Pouliot^[5] in the University Laval-Canada, comparing milk pasteurized by conventional heating and by induction heating, showed that when working, in a UHT pasteurization process, with induction heating we can avoid or regulate the Maillard reaction (Formation of flavours and browning compounds) this improves the sensory characteristics in the milk and dairy products. (For more data about dairy industry read Appendix A)

It was reported in another scientific paper in Brazil ^[6] that using ferritic stainless steel (common use in Induction heating systems) in sugar manufacture plants, has several advantages because this metal is chemically and biologically inert, does not affect taste or colour of the sugar and lower the risk of micro-organism colony growth.

1. Induction heating has good energy and exergy efficiency

[pic 2]Basaran et al. ^[7] and a group of engineers at the University of Celal Bayar-Turkey, compared an induction heater pasteurization system with a DPHE (Double Pipe Heat Exchanger) pasteurization system, to evaluate energy and exergy; the results show that the pasteurization system with induction heater needs less energy and exergy input than DPHE.(Exergy also called second law efficiency is the maximum useful work during a process).

After theoretical calculations, for both applications, it was found effectiveness or first law efficiency of heat transfer with the inductive heating system is 95.00% energy efficiency and 46.56% exergy efficiency while the conventional heating system with the electric boiler is 75.43% energy efficiency and 16.63% exergy efficiency. (Appendix B give more data about energy and exergy)[pic 3]

 Thanks to these results, the engineers concluded that apply the inductive method in tomato pasteurization, strawberry jam^[8], milk, and honey pasteurization^[9] is more efficient than the DPHE heating system. (To clarify this information, most factories run on fossil fuels, and fossil fuels are much less efficient, 40-65% effectiveness^[10], than the commercial electrical method in this study.)

1. Induction system offers to reduce the clogging in the system

Clogging due to the unwanted material accumulated on the tube surfaces of the heat exchangers is one of the main problems in the food industry, the gunk in the interior of these tubes decreases the cycle-life of the heat exchanger^[11]. According to experimental results, this effect can be minimized using electromagnetic induction. R. Martel, Y. Pouliot5 discovered that working with induction the amount of protein on the heating surface is less. This improves cleaning efficiency, increasing production run length with a reduction in the cost of production capacity ^[12] and a reduction of the waste-water from the process^[13].

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