Researchers from the University of Massachusetts, Amherst Department of Food Science have developed and validated a rapidly vaporizing antimicrobial liquid designed for dry sanitization in low-moisture food processing facilities, offering a potential alternative to highly flammable alcohol-based sanitation systems commonly used in these environments. The findings were published in the Journal of Food Protection.

The project addresses the longstanding challenge in dry food production of controlling pathogens without introducing excess moisture. Microorganisms such as Salmonella and Cronobacter have been implicated in outbreaks linked to low-moisture foods, yet traditional wet sanitation methods can increase microbial risks in dry environments.

Acknowledging the need for low-moisture sanitation solutions, the researchers formulated an antimicrobial liquid consisting of a 3 percent water in a cyclomethicone (a type of quickly evaporating silicone) emulsion carrying 200 millimolar acetic acid. The system was designed to deliver antimicrobial activity while maintaining volatility and reduced flammability compared with alcohol-based sanitizers.

Antimicrobial Efficacy Against Desiccated Pathogens

Laboratory testing showed that the formulation achieved greater than a 7-log reduction of desiccated Salmonella and Cronobacter on stainless steel coupons within 10 minutes at 22 °C. The experiments used multi-strain pathogen cocktails that had been desiccated under low relative humidity conditions (33 percent equilibrium relative humidity), simulating dry food production environments.

The researchers reported that controlled dispersion of water within the cyclomethicone carrier improved antimicrobial performance. Earlier experiments using nonpolar solvents alone produced inconsistent pathogen reduction when bacterial cells were highly desiccated. Introducing small amounts of dispersed water appeared to enhance antimicrobial activity by promoting membrane damage and osmotic stress in bacterial cells.

The study also examined evaporation characteristics of several solvents commonly used or proposed for sanitation. Dynamic vapor sorption analysis showed that nonpolar liquids such as cyclomethicone exhibited relatively stable evaporation rates across humidity conditions, whereas water evaporation varied significantly with environmental humidity.

According to the authors, the formulation’s evaporation profile indicates it could function as a dry sanitation agent. Most components evaporated quickly after application, leaving only a small amount of emulsifying agent residue.

Lower Flammability Compared with Alcohol-Based Sanitizers

One of the motivations for the research was the safety implications of alcohol-based sanitation systems in food facilities. Alcohol sanitizers can present flammability hazards and may subject facilities to fire code regulations.

Closed-cup flashpoint testing showed the developed emulsion had a flashpoint of approximately 80 °C. By comparison, ethanol–water mixtures commonly used for sanitation have flashpoints between 12 °C and 24 °C depending on concentration.

The authors suggested the higher flashpoint indicates a substantially lower flammability risk relative to alcohol-based systems.

Cleaning Remains Critical for Effective Sanitization

To evaluate the system under more realistic conditions, the researchers conducted a hand-cleaning validation experiment using stainless steel surfaces coated with dried nonfat milk films contaminated with Salmonella or Cronobacter. These films simulated residues that may accumulate from spills or leaks in processing environments.

Initial spray-and-hold applications of the antimicrobial liquid produced inconsistent pathogen reduction due to the protective effect of the dried food residue. The researchers found that effective decontamination required physical cleaning steps, including scraping and scrubbing to remove soil before sanitizer application.

After this mechanical cleaning step, a second application of the antimicrobial liquid achieved complete surface decontamination following ten minutes of contact time.

Potential Application and Regulatory Considerations

The proof-of-concept study demonstrated that volatile nonpolar liquids can be formulated to deliver antimicrobial activity in low-moisture sanitation systems. The observed pathogen reductions meet the U.S. Environmental Protection Agency’s (EPA’s) performance threshold for disinfectants on hard, nonporous surfaces.

However, the formulation would still require regulatory approval as an “antimicrobial pesticide” and evaluation for use on food-contact surfaces before commercial adoption.

Future Research Needs

The researchers also noted that the emulsion is thermodynamically unstable over time, meaning formulation stability and delivery performance will require further optimization. Future studies could examine stabilization technologies, environmental conditions, and emulsifier concentrations to improve antimicrobial delivery.

Overall, the findings suggest that low-moisture antimicrobial emulsions may offer a new approach to sanitation in dry food processing environments, where minimizing water use while controlling persistent pathogens remains a significant challenge.