Ohmic baking of sponge cake

OLIVERA, DANIELA F.; GOÑI, SANDRO MAURICIO; SALVADORI, VIVIANA O.

Buenos Aires

Congreso; WCCE11 - 11th World Congress of Chemical Engineering; 2023

Asociación Argentina de Ingenieros Químicos

The aim of this work was to assess the technological and energetic aspects related to ohmic cooking of sponge cake batters. During traditional oven baking (OB), heat is transported by conduction, convection and radiation from the surrounding ambient to food, so profiles of temperature and moisture content are observed inside the system, in consequence the crumb is heterogeneous. In ohmic heating (OH) the electric current flowing through the food allows to increase the temperature in a volumetric and uniform way. In this work an acrylic ohmic cell with two parallel stainless-steel electrodes was built (9 cm gap). Sponge cake batter was made by mixing a commercial dry premix, eggs and milk. For OH baking, a constant voltage difference (180 and 220 V) was used, at 50 Hz. Cell was filled with 1.5 cm of batter (125 g). During the test, current and surface temperature were recorded. The final time was set when surface temperature reached a plateau. For comparison, OB was performed in a domestic electric oven at 180 ºC, using the same sample size. During this test inner temperature was measured; baking time was set when the inner temperature reached 95 ºC [1]. After cooking, weight loss, surface and internal color, crumb density, sample height, pore size distribution and crumb texture were measured. Also, the energy consumption and efficiencies were estimated.For OH the baking time was 12 and 7.5 min for 180 and 220 V respectively, while for OB was 13.3 min. During OH the sample top surface is in contact with cool air, so the measured temperature is lower than the internal one. Then the measured cooking times are expected to be higher than the real ones. Weight loss was 5.2 % and 7.7 % for OH at 180 and 220 V respectively, while for OB was 12.1 %. In OH crust is absent; weight loss is due to volumetric water evaporation, whilst in OB crust is present. This feature is also reflected in surface L*a*b* values, the characteristic browning of baked goods is absent in OH.Crumb density was lower for OH, accordingly size increase was higher, and a more uniform surface height was reached. Pore size distribution was assessed from digital images and image processing; for OH a higher number of pores per unit area was obtained, with lower pore size and more uniform distribution. The firmness and springiness of OH crumb was higher than of OB crumb.The specific energy consumption for OH was 547 and 510 kJ/kg at 180 and 220 V respectively, while for OB was 9293 kJ/kg. Energy efficiencies were estimated as 57 % and 77 % for OH at 180 and 220 V respectively, and 5.6 % for OB. Note that a higher load (up to 4 samples) can be used in OB, which will diminish specific energy consumption and increase efficiency.Considering quality and energetic aspects, OH appears as a promising technology for sponge cake baking. In future works consumer acceptability will be addressed, and device design (current frequency and waveform) and system control.