Scientists discovered a powerful new method to kill dangerous bacteria called Pseudomonas aeruginosa that spoils refrigerated foods like milk and meat. They combined two techniques: first, they exposed the bacteria to cold temperatures for 24 hours, then treated them with cold plasma (a special type of energy). This two-step approach killed about 89% of the bacteria and caused permanent damage to their cells. The method works by attacking the bacteria from multiple angles at once—damaging their protective membranes, breaking down their energy systems, and blocking their survival mechanisms. When tested on pasteurized milk stored in the refrigerator, the treatment successfully prevented the bacteria from coming back. This discovery could help food companies keep refrigerated products fresher and safer for longer without using heat or harsh chemicals.

The Quick Take

  • What they studied: Whether combining cold temperature exposure with cold plasma treatment could effectively kill Pseudomonas aeruginosa bacteria that spoil refrigerated foods
  • Who participated: Laboratory experiments using Pseudomonas aeruginosa bacteria and pasteurized milk samples; no human participants were involved
  • Key finding: The combined cold-stress-then-cold-plasma treatment killed approximately 89% of bacteria and caused irreversible damage to bacterial cells, with 98% of cells showing signs of membrane rupture
  • What it means for you: This technique may eventually help food companies keep refrigerated products safer and fresher longer without using heat or chemical preservatives, though it’s still in the research phase and not yet available for consumer use

The Research Details

Researchers developed a two-step treatment process to kill harmful bacteria. First, they exposed bacteria to cold temperatures (4°C) for 24 hours to weaken them. Then, they applied cold plasma—a special form of energy created by applying high voltage (50,000 volts) for 180 seconds. They tested this combination on pure bacterial cultures and then on real pasteurized milk to see how well it worked.

The scientists used multiple laboratory techniques to understand exactly how the treatment killed the bacteria. They examined the bacteria under microscopes, measured chemical changes inside the cells, and used computer modeling to predict which bacterial structures the treatment would damage. This multi-method approach helped them understand not just that the bacteria died, but why and how the treatment worked.

The researchers also tested whether the bacteria could recover after treatment and whether the method affected the quality of milk samples, ensuring the approach was practical for real food applications.

This research matters because Pseudomonas aeruginosa is a major problem in the food industry—it causes spoilage in refrigerated products and can sometimes make people sick. Current methods to control this bacteria often use heat (which can damage food quality) or chemical preservatives (which some consumers want to avoid). This new approach offers a non-thermal alternative that might preserve food quality better while still providing strong protection against bacterial growth.

The study used rigorous scientific methods including microscopy, biochemical measurements, and computer modeling to validate results. The researchers tested their approach both in pure bacterial cultures and in real food (pasteurized milk), which strengthens confidence in the findings. However, the study was conducted in laboratory conditions, so real-world effectiveness in commercial food production may differ. The specific bacterial strain tested may not represent all variations of this bacteria species.

What the Results Show

The combined cold-stress-then-cold-plasma treatment achieved approximately 89% sterilization efficiency, meaning it killed about 9 out of every 10 bacteria. More importantly, the bacteria that survived showed severe, irreversible damage—98% of the bacterial cells had ruptured membranes, indicating they could not recover or reproduce.

The treatment worked through multiple simultaneous attacks on the bacteria. The cold pre-treatment weakened the bacteria’s defenses, making them more vulnerable. The cold plasma then generated reactive chemicals (hydrogen peroxide, ozone, and hydroxyl radicals) that attacked the bacteria’s protective membranes, caused them to leak their internal contents, and damaged their internal structures beyond repair.

The treatment also disrupted the bacteria’s energy production system by depleting ATP (the molecule cells use for energy) and damaging key enzymes needed for survival. Additionally, it blocked the bacteria’s ability to produce protective proteins that normally help them survive stress conditions.

When applied to pasteurized milk stored in refrigeration, the treatment successfully prevented bacterial regrowth throughout the storage period, suggesting it could be practical for real food applications.

Beyond killing the bacteria, the treatment also reduced the bacteria’s ability to cause harm in other ways. It decreased bacterial motility (movement), prevented them from clumping together, and reduced production of pyocyanin (a toxic pigment that can damage food quality and potentially harm consumers). Computer modeling showed that the reactive chemicals produced by cold plasma specifically targeted essential bacterial proteins involved in DNA replication, folate synthesis, and stress response—explaining why the bacteria couldn’t survive or adapt.

Previous research has shown that cold plasma alone can kill bacteria, and cold stress alone can weaken them. This study’s key innovation is demonstrating that combining these two approaches creates a synergistic effect—meaning the combination works better than either method alone. The 89% kill rate with irreversible damage is notably higher than what either treatment typically achieves independently, suggesting this sequential approach represents a meaningful advance in non-thermal food preservation technology.

This research was conducted entirely in laboratory conditions using pure bacterial cultures and milk samples, not in actual commercial food production environments. The study focused on one specific bacterial strain, so results may not apply equally to all variations of Pseudomonas aeruginosa. The researchers did not test the method on all types of refrigerated foods, so effectiveness on products like fresh produce, seafood, or other dairy items remains unknown. Long-term effects on food nutritional quality and taste were not thoroughly evaluated. Additionally, the practical and economic feasibility of implementing this technology in commercial food processing facilities was not assessed.

The Bottom Line

Based on this research, the cold-stress-then-cold-plasma approach shows strong promise as a food safety tool (high confidence in laboratory effectiveness). However, it is not yet ready for consumer or commercial use—further testing in real food production settings is needed before recommendations can be made. Food scientists and companies should monitor this technology’s development, as it may eventually offer a valuable alternative to heat-based or chemical preservation methods.

Food industry professionals, food safety scientists, and refrigerated food manufacturers should pay attention to this research as it develops. Consumers interested in food safety and preservation methods without chemical additives may eventually benefit. People with concerns about food spoilage or foodborne illness may find this technology relevant in the future. However, this research is not yet applicable to individual consumers or home food storage.

This is early-stage research. Realistic timeline expectations: 2-5 years for additional laboratory validation, 5-10 years for testing in commercial food production settings, and potentially 10+ years before this technology might be available in commercial food processing. Consumers should not expect to see this in stores or use it at home in the near term.

Want to Apply This Research?

  • Users could track refrigerated food freshness by logging the date products are opened and noting any signs of spoilage (odor, appearance, texture changes), then comparing actual shelf life to manufacturer claims. This creates a personal baseline for understanding current food preservation effectiveness.
  • Users could set reminders to check refrigerated products on specific days and log observations about freshness, helping them understand which storage methods and products maintain quality longest. This awareness could inform future purchasing decisions once new preservation technologies become available.
  • Establish a weekly food quality check habit where users photograph and note the condition of frequently-purchased refrigerated items. Over months, this creates a personal data set showing actual product shelf life, which can be compared against industry standards and adjusted based on individual storage practices.

This research describes laboratory findings about a novel food preservation technique that is not yet commercially available or approved for use in food production. The results are promising but represent early-stage research conducted under controlled laboratory conditions. Actual effectiveness in commercial food production may differ. This information is for educational purposes only and should not be used to make decisions about food safety or preservation. Always follow current food safety guidelines and manufacturer recommendations for storing and handling refrigerated foods. If you have concerns about food spoilage or foodborne illness, consult with food safety professionals or your healthcare provider. This technology is not yet available for consumer use.