Measurements and predictive modelling of heat fluxes in continuous baking ovens

Bakery product characteristics as influenced by convection heat flux

“…These values are within the range of instant heat flux values reported in the present study. Lower values were reported by Fahloul et al (1995), namely 1700-2000 J/s m 2 measured in a tunnel-type biscuit oven operated at 200°C with air velocities ranging from 1 to 3 m/s, and Carvalho and Martins (1992) reported 1200-900 J/s m 2 for an indirect-fired experimental oven kept at a constant 220°C with an air velocity of 0.6 m/s. Under constant baking conditions in an experimental oven kept at 300°C with an air flow of 1 m/s, heat fluxes were reported as 8000-19,000 J/s m 2 (De Vries et al, 1995).…”

“…The proportion of each individual mode of heat transfer in the baking process depends on oven design, configuration and operation. Several authors have studied the contribution of individual modes of heat transfer in bread, biscuit and cake baking using electrically powered, forced convection or gas-fired ovens (Baik, Grabowski, Trigui, Marcotte, & Castaigne, 1999;Baik, Marcotte, & Castaigne, 2000;Carvalho & Martins, 1992;Fahloul, Trystram, McFarlane, & Duquenoy, 1995;Krist-Spit & Sluimer, 1987;Standing, 1974). Radiation was found to be the predominant mode of heat transfer (Dostie, 2002), accounting for between 50% and 80% of total heat, while convection was the least important mode in conventional baking ovens.…”

Recent Advances in the Studies of Bread Baking Process and Their Impacts on the Bread Baking Technology

“…Heat flux is defined as the heat transfer rate per unit area that is required for baking from the oven chamber to the product (Van Son, 2001). Heat flux measurement was claimed to be the more useful method than air temperature measurement, for controlling the quality of bakery products (Fahloul et al, 1995;Carvalho & Nogueira, 1997;Van Son, 2001). For bread, Carvalho and Nogueira (1997) showed the influence of airflow velocity in an oven chamber on heat flux to bread as well as the possibilities to optimize the heat flux on the top, bottom and side of the product to obtain a better heat distribution.…”

“…To measure the total heat flux, Fahloul et al (1995) used a sensor made of copper joined to a steel heat sink by a copper bridge fitted with 2 thermocouples. The temperature readings from these 2 thermocouples together with temperatures of the heat sink and ambience were used to calculate the total heat flux.…”

Characterization of sponge cake baking in an instrumented pilot oven

“…The sensitive element was assumed to have an emissivity similar to the surface of the product (0.9-0.95). In other cases, the heat flux was calculated from time-temperature recordings (Fahloul, Trystram, Mcfarlane, & Duquenoy, 1995;McFarlane, 1992;Li & Walker, 1996;Zareifard, Marcotte, & Dostie, 2006). The influence of process parameters such as air velocity and temperature have been studied in relation to sponge cake baking (Sato, Matsumura, & Shibukawa, 1987) where variation in air velocity mainly affected the weight loss (mainly due to water evaporation) via the product surface, especially in the case of forced air convection.…”