All these properties specifically depend upon the wavelength of the infrared source and physical properties of the food product, e.g. composition – moisture content, surface roughness – properties. Among these, absorptivity is a significant factor since IR absorption (fundamentally equal to emissivity when the material and IR source are at the same temperature) leads to heating due to increases in thermal molecular vibrational activity (Siegel and Howell, 2002). Transmitted energy is, however, attenuated exponentially with penetration, and attenuation factor determines energy absorption as a function of product depth (Sakai and Mao, 2006). The intensity is then gradually lost, and this loss is described by Beer–Lambert‘s law. The intensity of spectral radiation is attenuated exponentially as it passes through an absorbing or scattering medium