Enhancing Spore Inactivation: Low-Intensity Pulsed Electric Field Combined with Ohmic Heating and Germinant...

Area of Science:

• Food Science
• Microbiology
• Biotechnology

Background:

• Bacterial spores, like Alicyclobacillus acidoterrestris (AAT), are highly resistant to conventional inactivation methods such as pasteurization.
• Persistent spores pose a significant risk to food safety and quality.

Purpose of the Study:

• To investigate a "germination-inactivation" strategy for AAT spores using L-valine and low-intensity pulsed electric fields (PEFs).
• To evaluate the synergistic effect of germination agents and PEFs combined with ohmic heating (OH) on spore inactivation.

Main Methods:

• Identified optimal germinant concentration (40 mM L-valine) through germination curve analysis.
• Applied PEF treatment (0.18 kV/cm for 210 s) to germinated AAT spores, with and without ohmic heating.
• Utilized scanning electron microscopy (SEM) and laser confocal microscopy to assess spore structural integrity and intracellular leakage.

Main Results:

• The combination of 40 mM L-valine and PEF treatment with OH reduced AAT spore counts by 1.73 log units, significantly higher than PEF alone (0.54 log units reduction).
• Germination agents markedly reduced spore resistance to PEF and OH.
• SEM and microscopy confirmed structural disruption and leakage of intracellular components (nucleic acids, proteins) in treated spores.

Conclusions:

• Low-intensity PEF combined with spore germination agents is an effective and energy-efficient method for bacterial spore inactivation.
• This approach offers a promising strategy for enhancing microbial safety in food processing.
• Further research into spore germination agents and PEF inactivation holds potential for novel food preservation techniques.