Cake baking in tunnel type multi-zone industrial ovens - Part I. Characterization of baking conditions

Baking conditions were observed for two different multi-zone industrial scale ovens: a gas fired band oven and an electric powered mold oven. In each zone of both ovens, parameters measured were: internal temperature profile, air velocity absolute humidity and oven wall temperature. Air temperatures were higher close to the oven wall than at the center of ovens tested. Absolute air humidity in the gas fired band oven (0.0545-0.246 kg H2O/kg dry air) was higher than in the electric fired mold oven (0.0207-0.0505 kg H2O/kg dry air). The relative air velocities in the ovens were 0-0.437 m/s, which resulted in convective heat transfer coefficients of 5.7-7.4 W/m(2)K and mass transfer coefficients of 3.94 x 10(-8)-5.12 x 10(-8) kg/m(2) s Pa. The average rate of total energy transferred to each product was 71992-85339 W. A proportion of 26-38.4% was the sensible heat absorbed with 61.6%-74% of the heat absorbed as the latent heat of vaporization of moisture. Radiative heat was responsible for 66.2-81.5% of the heat delivered to the top surface of products for cake baking in direct fired industrial ovens. (C) 2000 Elsevier Science Ltd. All rights reserved.