Ohmic heating of peaches in the wide range of frequencies (50 Hz to 1 MHz).

Journal of food science · 2010 · Mixed · Low evidence

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MixedLow evidencePaper 3270

Study snapshot

PublicationJournal of food science · 2010

Study typeother

Reported directionMixed

Evidence ratingLow

Abstract

UNLABELLED: The ohmic heating (OH) rate of peaches was studied at fixed electric field strength of 60 V.cm⁻¹, square-shaped instant reversal bipolar pulses, and frequencies varying within 50 Hz to 1 MHz. Thermal damage of tissue was evaluated from electrical admittivity. It showed that the time for half disruption (τ(T)) of tissue was required more than 10 h at temperatures below 40 °C. However, cellular thermal disruption occurred almost instantly (τ(T) < 1 s) at high temperatures (> 90 °C). Electrical conductivity σ(o) and admittivity σ(o)* of tissue at T(o)= 0 °C and their temperature coefficients (m, m*) were calculated. For freeze-thawed tissues, σ and σ* as well as m and m* were nearly indifferent to the frequency. However, for the intact tissue, both σ(o), σ(o)* and m, m* were frequency dependent. For freeze-thawed product, the power factor (P) was approximately equal to 1 and indifferent to the frequency and temperature. On the other hand, strong frequency dependence was observed for intact tissue with the minimum P approximately equal to 0.68 in the range of tens of kHz. The time required to reach a target temperature t(f) was evaluated. The t(f) increased with frequency up to the middle of the range of tens of kHz and thereafter continuously decreased. Samples exposed to the low-frequency electric field demonstrated faster electro-thermal damage rates. The textural relaxation data supported more intense damage kinetics at low-frequency OH. It has been demonstrated that a combination of high-frequency OH with pasteurization at moderate temperature followed by rapid cooling minimizes texture degradation of peach tissue. PRACTICAL APPLICATION: In this study, we investigated the electric field frequency effect on the rate of OH of peaches. It was shown that the time required for reaching the target temperature is strongly dependent upon the frequency. Samples exposed to low-frequency OH demonstrated higher electro-thermal damage rates. It has been shown that the combination of high-frequency OH with pasteurization at moderate temperature followed by rapid cooling minimizes texture degradation of peach tissue. Obtained results provide new information on the impact of electric field frequency on OH, which is useful for OH process design.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeother

Effect directionmixed

PopulationNot supplied

Sample sizeNot supplied

ExposureELF

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Ohmic heating of peaches at 60 V·cm−1 with frequencies from 50 Hz to 1 MHz showed strong frequency dependence in intact tissue for electrical properties (conductivity/admittivity, temperature coefficients) and power factor, while freeze-thawed tissues were nearly indifferent to frequency. Time to reach a target temperature increased with frequency up to the middle of the tens-of-kHz range and then decreased at higher frequencies. Low-frequency exposure produced faster electro-thermal damage and more intense texture damage kinetics; combining high-frequency ohmic heating with moderate-temperature pasteurization and rapid cooling minimized texture degradation.

Outcomes measured

Ohmic heating rate/time to reach target temperature as a function of frequency
Thermal/electro-thermal tissue damage kinetics (time for half disruption, τ(T))
Electrical conductivity and admittivity and their temperature coefficients
Power factor (P) frequency/temperature dependence
Texture degradation/relaxation outcomes under different frequencies

Limitations

No sample size reported in abstract
Study is on food tissue (peaches), not human/animal health outcomes
Exposure metrics beyond field strength and frequency range (e.g., current density, energy deposition) not provided in abstract

View raw extracted JSON

{
  "study_type": "other",
  "exposure": {
    "band": "ELF",
    "source": "other",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Ohmic heating rate/time to reach target temperature as a function of frequency",
    "Thermal/electro-thermal tissue damage kinetics (time for half disruption, τ(T))",
    "Electrical conductivity and admittivity and their temperature coefficients",
    "Power factor (P) frequency/temperature dependence",
    "Texture degradation/relaxation outcomes under different frequencies"
  ],
  "main_findings": "Ohmic heating of peaches at 60 V·cm−1 with frequencies from 50 Hz to 1 MHz showed strong frequency dependence in intact tissue for electrical properties (conductivity/admittivity, temperature coefficients) and power factor, while freeze-thawed tissues were nearly indifferent to frequency. Time to reach a target temperature increased with frequency up to the middle of the tens-of-kHz range and then decreased at higher frequencies. Low-frequency exposure produced faster electro-thermal damage and more intense texture damage kinetics; combining high-frequency ohmic heating with moderate-temperature pasteurization and rapid cooling minimized texture degradation.",
  "effect_direction": "mixed",
  "limitations": [
    "No sample size reported in abstract",
    "Study is on food tissue (peaches), not human/animal health outcomes",
    "Exposure metrics beyond field strength and frequency range (e.g., current density, energy deposition) not provided in abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "ohmic heating",
    "electric field frequency",
    "peach tissue",
    "electro-thermal damage",
    "conductivity",
    "admittivity",
    "power factor",
    "texture degradation",
    "pasteurization"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1111/j.1750-3841.2010.01778.x
PubMed: 21535544

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