The effects of the spectral distribution in the infrared ray range on radiative heating of food were studied. Baking tests were carried out in closed (oven) and open systems with two types of heaters; a far-infrared ray heater (N1) and a seathed heater (EM) which radiates relatively short wave rays. For the samples, bread and food model which was made of wet filter papers were used. After baking, the moisture loss, the surface temperature, the center temperature were measured.
The result in closed system, of which the surface temperature of heater was controlled at 400°C, showed the heat receiving rate of bread from N1 was faster than that from EM. Measured moisture distribution of food model indicated that the moisture loss rate at the inside was faster than that at the surface in. the case of EM.The EM heating in open system resulted in lower surface temperature and thicker crust of bread than N1 heating.
These results suggest that the short wave rays penetrated deeper through the food surface than the long wave rays.