Need to Know

• A survey of 40 low-moisture food (LMF) industry professionals identified gaps in sanitation practices, moisture management, and microbial testing
• Dry cleaning was more common than wet cleaning, although 22 percent of respondents reported using flood cleaning at least monthly
• Respondents' definitions of sanitation breaks varied, with many diverging from FDA guidance for LMF sanitation programs
• Nearly half of respondents were unsure of maximum relative humidity levels in dry processing zones, and more than 20 percent reported recurring uncontrolled moisture events
• Salmonella was the most commonly targeted pathogen in environmental monitoring and finished-product testing, with testing frequencies varying by facility size

A pre-proof to bublished in the Journal of Food Protection, the study surveyed 40 food safety and quality professionals with experience in LMF production to characterize industry practices related to sanitation, lot segregation, moisture management, environmental monitoring, and finished-product microbial testing. Respondents represented manufacturers of bakery products, ready-to-eat (RTE) snacks, spices and grains, dairy powders, confections, and other LMFs.

LMFs, defined as foods with a water activity (a_w) of 0.85 or below, do not support the growth of foodborne pathogens under normal dry conditions. However, pathogens such as Salmonella can persist in LMFs and their processing environments for extended periods, and moisture introduced through sanitation or uncontrolled water events can create conditions conducive to pathogen growth and spread.

One-Fifth of Respondents Use Flood Cleaning Monthly

Survey respondents generally reported practices intended to limit moisture introduction during sanitation. Dry-cleaning methods were used more frequently than wet-cleaning methods, with 95 percent of respondents reporting wiping, brushing, or scraping at least weekly, and 84 percent reporting vacuuming at least weekly.

Meanwhile, 68 percent of respondents reported never using flood cleaning (the broad application of water across equipment and the surrounding environment), although 22 percent reported using the method at least monthly. Equipment buildup reduction was the most common factor influencing dry-cleaning frequency (74 percent), while pathogen control was the most common factor influencing wet-cleaning frequency (82 percent).

Despite the respondents’ cited reasons for the use of wet cleaning, in a February 2026 article for Food Safety Magazine, Dr. Snyder and co-author Mirdamadi explained that wet sanitation in dry environments often increases risk, and explained how LMF producers can balance the pressures driving wet-cleaning decisions with the risks wet cleaning pose.

“Environmental sanitation programs do not result in a sterile environment, devoid of all viable microorganisms. Rather, some microbial cells will persist after either wet or dry sanitation. Consequently, the introduction of water into the environment enhances the ability of those remaining microbes to grow,” the article explains.

Sanitation Breaks Inconsistent with FDA Guidance

The researchers also found inconsistencies in how manufacturers defined sanitation breaks, which are used to separate production lots and limit the potential scope of contamination events and recalls.

Nearly half of respondents (47 percent) defined sanitation breaks based on the sanitation method used, while 23 percent based their definitions on product changeovers, 15 percent on the scope of sanitation, and 5 percent on post-sanitation testing results. The remaining 10 percent did not provide a definition.

The researchers noted that many of these definitions diverged from FDA's January 2025 draft guidance for LMF sanitation programs, which defined sanitation breaks as cleaning followed by a sanitizing treatment of food-contact surfaces.

Relative Humidity Uncertainty and Uncontrolled Moisture Events

Despite widespread use of active drying practices following wet sanitation, uncertainty surrounding RH control was common among respondents.

Specifically, 32.5 percent were unsure of their facility's target RH in dry processing zones, while 22.5 percent reported variable targets. Nearly half (47.5 percent) were unsure of the highest RH experienced during normal operations.

Among respondents who performed wet sanitation, 81.1 percent reported using at least one active drying measure afterward, including wiping surfaces with cloths, using fans, increasing airflow, or applying compressed air.

Another Food Safety Magazine article written by Dr. Snyder and co-author Karl Thorson explains that, despite the important influence RH has on a facility’s ability to maintain an adequately dry environment, it is often overlooked as a critical environmental control.

“Elevated RH increases condensation risk, slows drying, promotes microbial growth over time, and complicates powder handling,” the article states. Effective humidity management through HVAC, airflow control, dehumidification, and pressure balancing should be understood as a critical food safety barrier in dry facilities.”

Uncontrolled moisture events were also reported. More than 20 percent of respondents indicated that condensation, equipment leaks, or water puddling occurred at least monthly in dry production areas.

The researchers highlighted the importance of RH monitoring and preventive maintenance for controlling moisture-related microbial risks. They also noted that certain drying practices, including compressed air and reusable cloths, could introduce cross-contamination risks if not properly managed.

Variations in Environmental Monitoring

The study also characterized environmental monitoring and finished-product testing practices for pathogens and hygiene indicators.

Salmonella was the most commonly targeted pathogen in both environmental monitoring and finished-product testing, while Listeria spp. was also frequently monitored. Testing for Cronobacter spp. was less common and was concentrated among dairy powder manufacturers.

Environmental monitoring for pathogens and hygiene indicators was conducted weekly by most study participants, although testing frequencies varied by microorganism and facility size.

Finished-product Salmonella testing was reported by 100 percent of small manufacturers, 92 percent of medium-sized manufacturers, and 96 percent of large manufacturers. Weekly testing was most common among medium-sized and large manufacturers, while small manufacturers most frequently reported monthly testing.

Study Conclusions and Limitations

Overall, the researchers concluded that surveyed LMF manufacturers generally reported sanitation practices intended to minimize water introduction, but opportunities remained to improve RH management, standardize understanding of sanitation breaks, and better characterize the relationship between moisture management and microbial contamination risks.

The authors emphasized that the study's relatively small, nonrandom sample and reliance on self-reported practices limited the generalizability of the findings. The results were intended to provide an exploratory characterization of reported practices rather than industry-wide estimates or evidence of the effectiveness of individual interventions.