High-intensity pulsed electric fields processing parameters affecting polyphenoloxidase activity of strawberry juice.

Abstract

High-intensity pulsed electric fields (HIPEF) were applied to strawberry juice to study the feasibility of inactivating polyphenoloxidase (PPO). Response surface methodology was used to evaluate the effect of HIPEF processing, in which total treatment time (1000 to 2000 μs), pulse frequency (50 to 250 Hz), pulse width (1.0 to 7.0 μs), and polarity (monopolar or bipolar) were the controlled variables at a constant electric field of 35 kV/cm. The proposed 2nd-order response functions were accurate enough to fit experimental results. Strawberry juice PPO was strongly reduced within the range of assayed conditions. HIPEF treatments were more effective in bipolar than in monopolar mode in inactivating PPO. Treatments of longer duration resulted in reductions of the enzyme activity. Moreover, it was feasible to minimize residual PPO activity (down to 2.5%) by selecting bipolar treatments at frequencies higher than 229 Hz and pulse widths between 3.23 and 4.23 μs for a constant total treatment time of 2000 μs.

AI evidence extraction

Main findings

High-intensity pulsed electric fields (35 kV/cm) strongly reduced polyphenoloxidase activity in strawberry juice across the tested conditions. Bipolar mode was more effective than monopolar, and longer treatment duration reduced enzyme activity; residual PPO activity could be minimized to 2.5% using bipolar treatments with frequency >229 Hz and pulse width 3.23–4.23 μs at 2000 μs total treatment time.

Outcomes measured

• Polyphenoloxidase (PPO) activity in strawberry juice
• Residual PPO activity (%)

Limitations

• No sample size reported in abstract.
• No health-related outcomes; study is on food enzyme inactivation.
• Frequency reported in Hz (pulse frequency); no EMF frequency band or SAR provided.

{
    "study_type": "other",
    "exposure": {
        "band": null,
        "source": "high-intensity pulsed electric fields (HIPEF) food processing",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "total treatment time 1000 to 2000 μs"
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "Polyphenoloxidase (PPO) activity in strawberry juice",
        "Residual PPO activity (%)"
    ],
    "main_findings": "High-intensity pulsed electric fields (35 kV/cm) strongly reduced polyphenoloxidase activity in strawberry juice across the tested conditions. Bipolar mode was more effective than monopolar, and longer treatment duration reduced enzyme activity; residual PPO activity could be minimized to 2.5% using bipolar treatments with frequency >229 Hz and pulse width 3.23–4.23 μs at 2000 μs total treatment time.",
    "effect_direction": "benefit",
    "limitations": [
        "No sample size reported in abstract.",
        "No health-related outcomes; study is on food enzyme inactivation.",
        "Frequency reported in Hz (pulse frequency); no EMF frequency band or SAR provided."
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "high-intensity pulsed electric fields",
        "HIPEF",
        "strawberry juice",
        "polyphenoloxidase",
        "enzyme inactivation",
        "response surface methodology",
        "pulse frequency",
        "pulse width",
        "polarity"
    ],
    "suggested_hubs": []
}

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