Effects of pH, temperature and pulsed electric fields on the turbidity and protein aggregation of ovomucin-depleted egg white.

Abstract

The effect of either pulsed electric fields (PEF) or thermal processing on protein aggregation of ovomucin-depleted egg white (OdEW) solutions at different pH was assessed by solution turbidity and SDS-PAGE. Heating to 60°C for 10min caused marked protein aggregation of OdEW at pH5, 7, and 9. At constant electric field strength (E=1.4-1.8kV/cm), PEF processing under high specific energy input (W=260-700kJ/kg) induced some protein aggregation at pH5 and 7, but not at either pH4 or 9. Similar effects of pH on protein aggregation were observed upon PEF processing at varied E (from 0.7 to 1.7kV/cm) but with constant W (713kJ/kg). Analysis by SDS-PAGE revealed that proteins in the OdEW solution at pH5 were most susceptible to both PEF- and heat-induced protein aggregation and lysozyme was only involved in the formation of insoluble aggregates under PEF. The present study shows that PEF treatment has considerable potential for minimizing protein aggregation in the processing of heat-labile egg white proteins. Retaining the OdEW proteins in solution during processing has potential industry application, for example, protein fortification of drinks with OdEW, where minimizing solution turbidity would be advantageous.

AI evidence extraction

Main findings

Heating to 60°C for 10 min caused marked protein aggregation of ovomucin-depleted egg white (OdEW) at pH 5, 7, and 9. Under PEF at E=1.4–1.8 kV/cm with high specific energy input (W=260–700 kJ/kg), some protein aggregation occurred at pH 5 and 7 but not at pH 4 or 9; similar pH-dependent effects were seen when varying E (0.7–1.7 kV/cm) at constant W=713 kJ/kg. SDS-PAGE indicated pH 5 proteins were most susceptible to both PEF- and heat-induced aggregation, and lysozyme was only involved in insoluble aggregates under PEF.

Outcomes measured

• Solution turbidity
• Protein aggregation
• SDS-PAGE protein profile
• Insoluble aggregate formation (lysozyme involvement)

Limitations

• No sample size reported in abstract
• Processing duration for PEF not stated
• Study is on a food protein solution (not a health/biological exposure study in humans or animals)
• Outcomes are physicochemical/biochemical measures (turbidity, aggregation) rather than health endpoints

{
    "study_type": "other",
    "exposure": {
        "band": null,
        "source": "pulsed electric fields (food processing)",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "10 min heating at 60°C (thermal comparator); PEF energy input W=260–700 kJ/kg and W=713 kJ/kg (processing duration not stated)"
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "Solution turbidity",
        "Protein aggregation",
        "SDS-PAGE protein profile",
        "Insoluble aggregate formation (lysozyme involvement)"
    ],
    "main_findings": "Heating to 60°C for 10 min caused marked protein aggregation of ovomucin-depleted egg white (OdEW) at pH 5, 7, and 9. Under PEF at E=1.4–1.8 kV/cm with high specific energy input (W=260–700 kJ/kg), some protein aggregation occurred at pH 5 and 7 but not at pH 4 or 9; similar pH-dependent effects were seen when varying E (0.7–1.7 kV/cm) at constant W=713 kJ/kg. SDS-PAGE indicated pH 5 proteins were most susceptible to both PEF- and heat-induced aggregation, and lysozyme was only involved in insoluble aggregates under PEF.",
    "effect_direction": "mixed",
    "limitations": [
        "No sample size reported in abstract",
        "Processing duration for PEF not stated",
        "Study is on a food protein solution (not a health/biological exposure study in humans or animals)",
        "Outcomes are physicochemical/biochemical measures (turbidity, aggregation) rather than health endpoints"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "pulsed electric fields",
        "PEF",
        "egg white",
        "ovomucin-depleted egg white",
        "protein aggregation",
        "turbidity",
        "SDS-PAGE",
        "pH",
        "thermal processing",
        "lysozyme"
    ],
    "suggested_hubs": []
}

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