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Inactivation of Listeria monocytogenes in milk by pulsed electric field
L D Reina1, Z T Jin, Q H Zhang
1Department of Food Science and Technology, Ohio State University, Columbus 43210, USA.
Abstract:
Pasteurized whole, 2%, and skim milk were inoculated with Listeria monocytogenes Scott A and treated with high-voltage pulsed electric field (PEF). The effects of milk composition (fat content) and PEF parameters (electric field strength, treatment time, and treatment temperature) on the inactivation of the bacterium were studied. No significant differences were observed in the inactivation of L. monocytogenes Scott A in three types of milk by PEF treatment. With treatment at 25 degrees C, 1- to 3-log reductions of L. monocytogenes were observed. PEF lethal effect was a function of field strength and treatment time. Higher field strength or longer treatment time resulted in a greater reduction of viable cells. A 4-log reduction of the bacterium was obtained by increasing the treatment temperature to 50 degrees C. Results indicate that the use of a high-voltage PEF is a promising technology for inactivation of foodborne pathogens.
Insights
High-voltage pulsed electric field (PEF) effectively inactivates Listeria monocytogenes in milk. Optimizing PEF parameters like temperature significantly enhances pathogen reduction, showing promise for food safety.
Area of Science:
- Food Science
- Microbiology
- Electrical Engineering
Background:
- Listeria monocytogenes is a significant foodborne pathogen.
- Effective methods for its inactivation in dairy products are crucial for public health.
- High-voltage pulsed electric field (PEF) is an emerging non-thermal processing technology.
Purpose of the Study:
- To evaluate the efficacy of high-voltage PEF for inactivating Listeria monocytogenes Scott A in pasteurized milk.
- To investigate the influence of milk fat content and PEF parameters (field strength, treatment time, temperature) on bacterial inactivation.
Main Methods:
- Pasteurized whole, 2%, and skim milk were inoculated with Listeria monocytogenes Scott A.
- Milk samples were treated using high-voltage PEF under varying conditions.
- Bacterial populations were enumerated post-treatment to determine log reductions.
Main Results:
- PEF treatment achieved 1- to 3-log reductions of Listeria monocytogenes at 25°C.
- Inactivation efficacy increased with higher electric field strength and longer treatment times.
- A 4-log reduction was achieved by increasing the treatment temperature to 50°C.
- Milk fat content did not significantly affect PEF inactivation efficacy.
Conclusions:
- High-voltage PEF is a promising technology for reducing Listeria monocytogenes in milk.
- PEF parameters, particularly temperature, are critical for achieving significant pathogen inactivation.
- PEF offers a potential non-thermal method for enhancing the safety of dairy products.