Infrared Cooking

Infrared Heating in Food Processing: An Overview Some ovens have both Near Infrared (wavelength < 1.25 µm - closer to visible light) and Far Infrared (wavelength = 15 - 1,000µm - closer to microwave)

FIR energy penetrates very little, almost all the energy being converted to heat at the surface of the food,

NIR wavelength region (wavelength < 1.25 µm), approximately 50% of the radiation is reflected back, while less than 10% radiation is reflected back at the FIR wavelength region.

However NIR penetrates deeper.
A study using NIR-I imaging reported a maximum penetration depth through tissue of ~3.2 cm. (1.25") [Deep-tissue optical imaging of near cellular-sized features | nature.com]

Table 4—. Penetration depth of NIR (0.75 to 1.4 μm) into food products.

Product Spectral peak (μm) Depth of penetration (mm)

Dough, wheat 1.0 4 to 6

Bread, wheat 1.0 11 to 12

Bread, biscuit, dried 1.0 4

0.88 12

Grain, wheat 1.0 2

Carrots 1.0 1.5

Tomato paste, 70% to 85% water 1.0 1

Raw potatoes 1.0 6

Dry potatoes 0.88 15 to 18

Raw apples 1.16 4.1

1.65 5.9

2.36 7.4

Product	Spectral peak (μm)	Depth of penetration (mm)
Dough, wheat	1.0	4 to 6
Bread, wheat	1.0	11 to 12
Bread, biscuit, dried	1.0	4
0.88	12
Grain, wheat	1.0	2
Carrots	1.0	1.5
Tomato paste, 70% to 85% water	1.0	1
Raw potatoes	1.0	6
Dry potatoes	0.88	15 to 18
Raw apples	1.16	4.1
	1.65	5.9
	2.36	7.4

A Comprehensive Review on Infrared Heating - Applications in Food Processing

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