Dielectric Properties of Mexican Dried Chili Peppers ( <i>Capsicum annuum</i> L.): <i>De Árbol</i> , <i>Guajillo</i> , and <i>Pasilla</i> at Microwave and Radiofrequency Ranges

ABSTRACT The dielectric properties of three types of dried chili peppers ( Capsicum annuum L.), De Árbol , Guajillo , and Pasilla , were measured at different temperatures (20°C, 40°C, 60°C) across a frequency range of 27 to 5000 MHz using the modified thru‐reflect‐line method, determining the permittivities of the air‐chili mixture (bulk permittivity: ε bulk ) and the solid sample (particle permittivity: ε part ). Additionally, the chili peppers were characterized by their moisture content, water activity ( a w ), color, and densities (bulk, tapped, and particle). The samples' moisture content ranged between 11.32%–16.80% (w.b.), a w varied from 0.555–0.595, and color parameters characterized each chili: De Árbol (red), Guajillo (dark red), and Pasilla (black‐brown). Guajillo pepper had the highest density values (bulk: 0.496 ± 0.007 g/cm 3 ; tapped: 0.565 ± 0.012 g/cm 3 ; particle: 1.200 ± 0.075 g/cm 3 ). The dielectric properties obtained using ε bulk and ε part decreased as frequency and temperature increased, with the dielectric properties from ε part showing higher values due to air removal. The dielectric constant decreased due to the effect of a w through moisture migration to the surface, which led to water evaporation. The loss factor decreased because of ionic conduction, where losses increased due to the higher mobility of ions at greater temperatures. Overall, at low radio frequencies, energy loss is dominated by ionic conduction, while at microwave frequencies, dipole polarization prevails.