Effect of blue light at different wavelengths on the inactivation of foodborne bacteria: evaluation of microbial susceptibility.

Abstract

This study evaluated the effects of Blue light technology at different wavelengths (405, 420, and 450 nm) and doses (144-1000 J cm) on the inactivation of food-related bacteria: Escherichia coli, Salmonella enterica subsp. enterica, Pseudomonas fluorescens, Listeria monocytogenes, Staphylococcus aureus, and Bacillus subtilis. Microbial responses varied with wavelength and dose. At the same dose, lower wavelengths achieved greater reductions. P. fluorescens and L. monocytogenes were the most susceptible (ca. 7.5 log CFU/mL reduction at 405 nm), while S. enterica was the most resistant (ca. 1.1 log CFU/mL reduction at 405 nm). Overall, 405 nm yielded the highest inactivation across all species, followed by 420 nm. At 450 nm, Gram (+) bacteria remained susceptible, indicating potential use in sanitation protocols, whereas Gram (-) bacteria were generally resistant, except for P. fluorescens. Blue light (BL) technology is an eco-friendly approach for bacterial inactivation in the food sector, leaving no residues and minimizing the risk of microbial resistance. These results can provide guidelines for selecting the wavelength and delivered dose to achieve microbial reductions, proposing the direct use of BL as a sanitization method in food processing.

AI evidence extraction

Main findings

Blue light at 405, 420, and 450 nm produced wavelength- and dose-dependent inactivation of multiple food-related bacteria. At the same dose, lower wavelengths achieved greater reductions; 405 nm showed the highest inactivation overall (e.g., ~7.5 log CFU/mL reduction for P. fluorescens and L. monocytogenes at 405 nm), while S. enterica was most resistant (~1.1 log CFU/mL reduction at 405 nm). At 450 nm, Gram-positive bacteria remained susceptible, whereas Gram-negative bacteria were generally resistant except P. fluorescens.

Outcomes measured

• Bacterial inactivation (log CFU/mL reduction)
• Microbial susceptibility by species
• Wavelength- and dose-dependent response

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    "study_type": "in_vitro",
    "exposure": {
        "band": "other",
        "source": "other",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "Bacterial inactivation (log CFU/mL reduction)",
        "Microbial susceptibility by species",
        "Wavelength- and dose-dependent response"
    ],
    "main_findings": "Blue light at 405, 420, and 450 nm produced wavelength- and dose-dependent inactivation of multiple food-related bacteria. At the same dose, lower wavelengths achieved greater reductions; 405 nm showed the highest inactivation overall (e.g., ~7.5 log CFU/mL reduction for P. fluorescens and L. monocytogenes at 405 nm), while S. enterica was most resistant (~1.1 log CFU/mL reduction at 405 nm). At 450 nm, Gram-positive bacteria remained susceptible, whereas Gram-negative bacteria were generally resistant except P. fluorescens.",
    "effect_direction": "mixed",
    "limitations": [],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "blue light",
        "405 nm",
        "420 nm",
        "450 nm",
        "dose",
        "bacterial inactivation",
        "Escherichia coli",
        "Salmonella enterica",
        "Pseudomonas fluorescens",
        "Listeria monocytogenes",
        "Staphylococcus aureus",
        "Bacillus subtilis",
        "food sector",
        "sanitization"
    ],
    "suggested_hubs": []
}

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