Analysis of modes of heat transfer in baking Indian rice pan cake (Dosa,) a breakfast food.

Heat transfer by individual modes is estimated during baking of rice (Oryza sativa) pan cake (Dosa), a traditional food. The mathematical expressions proposed could be used to modify the baking oven for controlling the individual modes of heat transfer to obtain the desired product texture, colour and flavour. Conduction from the rotating hot plate is found to be the most prominent mode of heat transfer and is critical for obtaining the desired product characteristics such as texture and flavour. Temperature profiles along the thickness of Dosa are obtained and compared with those obtained experimentally. Heat transfer parameters such as thermal conductivity and emissivity of Dosa are determined (0.42 W/m K and 0.31, respectively). The effect of material of construction of the hot plate such as alloy steel, teflon coated aluminum, cast iron and stainless steel on product texture was studied and stainless steel was found to give good surface finish to the product, which was confirmed by scanning electron microscope. Sensory evaluation was carried out to evaluate the product acceptability. The thermal efficiency of the baking oven was 51.5%.