title: Effects of shape and size of agar gels on heating uniformity during pulsed microwave treatment.
abstract: Model gel systems with different shape (sphere, cylinder, and slab) and size (180 and 290 g) were prepared with agar (5%) and sucrose (5%). Dielectric constant (ε'), loss factor (ε"), thermophysical properties, and temperature distribution of the model system were measured. Each agar model system was immersed and suspended in water, and then, heated in a microwave oven with intermittent heating until the core temperature reached 50 °C. The ε' and ε" of agar gels decreased when frequency increased. The density and thermal conductivity values of the agar gels were 1033 kg/m(3) and 0.55 W/m °C, respectively. The temperature distribution of sphere, cylinder, and slab was different when similar power doses were applied. The slab reached 50 °C in less time (10 min) and showed a more uniform heating than spheres and cylinders in both sizes. Agar model systems of 180 g heated faster than those of 290 g. The coldest point was the center of the model systems in all studied cases. Shape and size are critical food factors that affect the heating uniformity during microwave heating processes.
authors.affiliation: Dept. de Ingeniería Química, Alimentos y Ambiental Univ. de las Américas Puebla , Ex-Hacienda Santa Catarina Mártir S/N, Cholula, Puebla, 72810, México.
authors.forename: Nohemí
authors.initials: N
authors.lastname: Soto-Reyes
authors.affiliation: Dept. de Ingeniería Química, Alimentos y Ambiental Univ. de las Américas Puebla , Ex-Hacienda Santa Catarina Mártir S/N, Cholula, Puebla, 72810, México.
authors.forename: Ana L
authors.initials: AL
authors.lastname: Temis-Pérez
authors.affiliation: Dept. de Ingeniería Química, Alimentos y Ambiental Univ. de las Américas Puebla , Ex-Hacienda Santa Catarina Mártir S/N, Cholula, Puebla, 72810, México.
authors.forename: Aurelio
authors.initials: A
authors.lastname: López-Malo
authors.affiliation: Dept. de Electrónica, Div. de Ingenierías, Campus Irapuato-Salamanca, Univ. de Guanajuato, Carretera Salamanca - Valle de Santiago km. 3.5 + 1.8. Comunidad de Palo Blanco, Salamanca, Guanajuato, 36700, México.
authors.forename: Roberto
authors.initials: R
authors.lastname: Rojas-Laguna
authors.affiliation: Dept. de Alimentos, Div. de Ciencias de la Vida, Campus Irapuato-Salamanca, Univ. de Guanajuato, Carretera Irapuato-Silao km. 9, Irapuato, Guanajuato, 36500, México.
authors.forename: María Elena
authors.initials: ME
authors.lastname: Sosa-Morales
mesh_terms: D000362:Agar / Q000737:chemistry*; D003080:Cold Temperature; D003296:Cooking; D005511:Food Handling / Q000379:methods*; D005782:Gels; D006361:Heating; D006358:Hot Temperature; D006801:Humans; D008872:Microwaves; D008956:Models, Chemical; D013814:Thermal Conductivity; D014867:Water
chemical_list: D005782:Gels; D014867:Water; D000362:Agar
keywords: Agar model; microwave heating; shape and size; temperature distribution