Dielectric properties of Mexican sauces for microwave-assisted pasteurization process.

Area of Science:

• Food science and technology
• Electromagnetics
• Dielectric properties of materials

Background:

• Dielectric properties are crucial for designing high-frequency electromagnetic wave pasteurization processes.
• Mexican sauces are globally recognized for their flavor and nutritional value.
• Understanding dielectric behavior is essential for effective microwave-assisted food processing.

Purpose of the Study:

• To determine the complex relative permittivity of four representative Mexican sauces (chipotle chili, habanero chili, red, and green).
• To investigate the influence of temperature and frequency on dielectric properties.
• To identify optimal microwave frequencies for pasteurization based on dielectric behavior and penetration depth.

Main Methods:

• Complex permittivity measurements using the open coaxial probe method.
• Testing across temperatures from 25 to 85 °C and frequencies from 500 MHz to 6 GHz.
• Characterization of additional physical properties like moisture content, specific heat, viscosity, water activity, density, and electrical conductivity.

Main Results:

• Dielectric properties varied significantly with sauce formulation and were temperature-dependent.
• The loss factor showed frequency-dependent changes, indicating varying heating rates.
• 915 MHz demonstrated higher loss factors and greater penetration depth compared to 2,450 and 5,800 MHz, suggesting more uniform heating.

Conclusions:

• The dielectric properties of Mexican sauces are formulation-dependent and influenced by temperature and frequency.
• 915 MHz is the recommended frequency for microwave-assisted pasteurization of these sauces due to optimal heating speed and penetration depth.
• This research provides critical data for developing efficient and safe microwave pasteurization techniques for Mexican sauces.