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Baking with infrared heating

Identification

Key words Infrared, IR, heating, radiation, baking, bread, cake, crust, penetration depth
Latest version 2011/12/20
Completed by SP

How does it work?

Primary objective Reduction of baking time and energy consumption.
Working principle In infrared (IR) baking, thermal energy is transferred in the form of electromagnetic waves from the emitters (lamps) to the product. The radiation penetrates the surface of the bread/cake dough and is transformed into heat. The heat is then further distributed inside the dough by conduction and convection. Multiple IR lamps can be used to achieve an even heating process.

IR baking is efficient and instant, and high heat fluxes (heat transferred to the food surface) can be achieved. Heating of the surrounding air in the oven is not necessary, which lowers the energy consumption, as compared to conventional baking. The baking process can easily be controlled, with short start-up and shut-down times.

Absorbance of IR energy in dough-based products depends on wavelength, moisture content, surface characteristics, and dough composition. These properties change during the baking process. Penetration depth of the IR radiation depends, among other things, on the IR wavelength which can be adjusted. With a short penetration depth, heat is generated at the product surface allowing for crust formation and colour and aroma reactions to take place (5,7,8,9). For this purpose, halogen lamps are often used which provide near-IR radiation. If the penetration depth is large, the IR energy is absorbed quite similar to microwave energy which may imply moisture accumulation at the food surface (1).

The short baking times normally result in a thin crust. However, for IR baking using near-IR radiation where heat is generated at the surface, the crust is quickly formed and may become very thick. This could imply problems with low bread volume. A thick crust reduces the heat transfer to the inner parts of the bread, and can obstruct formation of the starch-gluten matrix that gives the bread its structure. Also, a thick crust restrains the expansion of the crumb. (4,7,8,9).
Combining IR heating with conventional or impingement heating is a good way to achieve fast and energy efficient baking of breads and cakes with a result comparable to that of conventionally baked products (3,4,8,9). IR can also be used as a complement to microwave baking to avoid problems with lack of crust and colour formation.

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Additional effects IR provides good control of the heat and mass transport during baking, which can be used for process design to tailor specific product characteristics such as crust thickness and colour and aroma formation.
Important process parameters Baking time, IR power, IR penetration depth (depending on wavelength), distance and inclination between IR lamps and product.
Important product parameters Moisture content, composition, product size and geometry.

What can it be used for?

Products Bread, cakes, cookies and other baked products.
Operations Baking
Solutions for short comings In a conventional oven heat is mainly transferred by convection from the hot air and by radiation from the oven walls to the product surface, followed by conduction inside the product. Heat transfer is poor which makes conventional baking a time and energy consuming process. Using more efficient heating techniques reduces energy consumption, reduces costs, and allows for time and space savings.

What can it NOT be used for?

Products Products that require long baking times to allow for desired chemical and physical conversions to take place; for example flavour and texture components may be difficult to adapt to the fast infrared baking process.

Products where it is desired to have a low surface temperature (for example some pastries).

Operations Only baking has been considered in this data sheet.
Other limitations High IR power may result in increased weight loss, firmness, low bread volume, and big pores in the crumb of the bread (5,7).
Risks or hazards Observe safety regulations when using IR equipment. Exposure to infrared radiation can result in heat damage and have chronic adverse effects on the eyes and skin.

Implementation

Maturity IR equipment for baking exists.
Modularity /Implementation IR ovens can be inserted in an existing production line.
Consumer aspects IR heating has been used in the restaurant business for the last 25 years. However, consumers may be sceptic towards IR heating, as it sometimes is assumed to be the same as irradiation of foods, which may be regarded as negative due to assumed health effects (2,6).
Legal aspects IR equipment should comply with the directive 2006/25/EC of the European Parliament on the minimum health and safety requirements regarding the exposure of workers to risks arising from physical agents (artificial optical radiation, 19th individual directive within the meaning of article 16(1) of directive 89/391/EEC).
Environmental aspects IR baking uses less energy than conventional baking.

Further Information

Institutes SP, DIL, TTZ
Companies Ircon
References 1. Datta A.K., Ni H. 2002. Infrared and hot-air-assisted microwave heating of foods for control of surface moisture. Journal of Food Engineering 51, 355-364.

2. De Barcellos M.D., Kügler J.O., Grunert K.G., van Wezemael L., Pérez-Cueto F.J.A., Ueland O., Verbeke W. 2010. Innovative Food Science & Emerging Technologies 11 (4), 721-732.

3. Demirekler P., Sumnu G., Sahin S. 2004 Optimization of bread baking in a halogen lamp-microwave combination oven by response surface methodology. European Food Research Technology 219, 341-347.

4. Demirkesen I., Sumnu G., Sahin S., Uysal N. 2011. International Journal of Food Science and Technology 46, 1809-1815.

5. Dessev T., Jury V. and Le-Bail A. 2011. The effect of moisture content on short infrared absorptivity of bread dough. Journal of Food Engineering 104: 571-576

6. FDA, Irradiation of Food and Packaging. http://www.fda.gov/Food/FoodIngredientsPackaging/IrradiatedFoodPackaging/ucm081050.htm. 2011-10-18.

7. Keskin S.O., Sumnu G. and Sahin S. (2004). Bread baking in halogen lamp-microwave combination oven. Food Research International 37: 489-495.

8. Olsson E.E.M., Trägårdh A.C., Ahrné L.M. 2005. Effect of near-infrared radiation and jet impingement heat transfer on crust formation of bread. Journal of Food Science 70 (8), E484-E491.

9. Sumnu G., Sahin S., Sevimli M. 2005. Microwave, infrared and infrared-microwave combination baking of cakes. Journal of Food Engineering 71, 150-155.



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Created by WikiSysop on 28 February 2012, at 13:10