Dielectric properties of tequila in the microwave frequency range (0.5–20 GHz) using coaxial probe

International Journal of Food Properties

Corona‐Chávez

et al. 2017

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Dielectric properties (DPs) of selected fruits: guava (Psidium guajava), mamey sapote (Pouteria sapota), red prickly pear (fruit from Opuntia streptacantha), and white prickly pear (fruit from Opuntia ficus-indica), as well as nopal (young cactus pads or cladodes from Opuntia ficus-indica) were studied. DPs were determined using the open-ended coaxial probe method at microwave frequencies (500 MHz-2 GHz) and temperatures of 20, 40, and 60ºC. At 20ºC and 915 MHz for unripe fruits, dielectric constant values ranged from 65.7 to 70.9, while the loss factor had values between 8.4 and 20.7. Both dielectric constant and dielectric loss factor were affected by temperature and frequency (p < 0.05). For example, loss factor for red prickly pear at 2450 MHz decreased from 13.88 at 20ºC to 12.8 at 40ºC and 11.7 at 60ºC. DPs of fruits were also affected by their ripening (quantified through the maturity index). In addition, penetration depth decreased with increasing frequency, ranging from 1.98 to 4.80 cm at 915 MHz and from 0.25 to 0.41 cm at 5800 MHz. Results are valuable to develop further applications with microwave technology for these foods, such as microwave-assisted disinfestation treatments or microwave drying.

Section: Samplesmentioning

confidence: 99%

Dielectric properties of guava, mamey sapote, prickly pears, and Nopal in the microwave range

Kataria

International Journal of Food Properties

Corona‐Chávez

et al. 2017

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“…After calibration, the sauces were poured in the 200 mL glass vessel and the coaxial probe was submerged 2 cm into the samples. It is important to mention that, for calibration and measurements, the probe was submerged 2 cm in order to produce a distance of about λ/8 from the probe tip to the base of the sample at the lowest frequency (Kataria, Olvera‐Cervantes, Corona‐Chávez, Rojas‐Laguna, & Sosa‐Morales, 2017a; Kataria, Sosa‐Morales, Olvera‐Cervantes, & Corona‐Chávez, 2017b). The permittivity of the sauces at five temperatures (25, 40, 55, 70 and 85 °C) and at frequency range from 500 MHz to 6 GHz was measured by quintuplicate.…”

Section: Methodsmentioning

confidence: 99%

Dielectric properties of Mexican sauces for microwave‐assisted pasteurization process

Hernandez-Gomez

Journal of Food Science

Sosa‐Morales

et al. 2020

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The dielectric properties and specifically the complex relative permittivity of foods are key elements for the design of pasteurization processes with high frequency electromagnetic waves. Mexican sauces are recognized worldwide for their flavor and nutritional properties. In this work, the complex permittivity of four of the most representative sauces of Mexican cuisine (chipotle chili, habanero chili, red and green sauce) is presented. The permittivity was measured with the open coaxial probe method at temperatures of 25, 40, 55, 70, 85 °C and in the frequency range of 500 MHz to 6 GHz. Additionally, moisture content, specific heat, viscosity, water activity, density and electrical conductivity are reported, these last three at 25 °C. Dielectric properties were affected by the sauce formulation. The loss factor of each sauce sample at any temperature presents significant changes in relation to the frequency. At 915 and 2,450 MHz, , which would cause a thermal runaway effect or the uncontrolled rise in temperature in the sauces during the microwave pasteurization. At 5,800 MHz, , which would give better control for microwave heating than at 915 and 2,450 MHz. At 915 MHz, the loss factor of all sauces is higher than at 2,450 and 5,800 MHz, therefore, more rapid heating can be produced. Moreover, at 915 MHz, microwaves exhibit higher penetration depth than at 2,450 and 5,800 MHz; therefore, at 915 MHz, the greatest uniform microwave dielectric heating would be achieved. Thus, 915 MHz is the frequency recommended for the studied sauces pasteurization.Practical ApplicationThis work provides the dielectric properties of Mexican sauces at different temperatures and their penetration depths in the microwave range, which are key information for further microwave‐assisted pasteurization process and for getting safer sauces for consumers. Moreover, this research supplies suggestions about what frequency for ISM (Industrial, Scientific and Medical) applications is the best for microwave‐assisted pasteurization according to the penetration depth of the electromagnetic wave in the sauces and microwave dielectric heating speed of the sauces.

“…The measurements were carried out from 0.25 to 25 GHz. The probe tip was calibrated with air, the metallic device called “short” included in the calibration kit, and distilled water at 25°C; error of the system was about 5% after calibration with ethanol 70% (Kataria, Sosa‐Morales, Olvera‐Cervantes, & Corona‐Chávez, ). Then, 300 mL of each beverage was placed in a 500 mL beaker, immersing the tip 2 cm below the liquid surface to ensure contact with the sample.…”

Section: Methodsmentioning

confidence: 99%

Dielectric Properties of Beverages (Tamarind and Green) Relevant to Microwave‐Assisted Pasteurization

González-Monroy

Kataria

Journal of Food Science

et al. 2018

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