MANHATTAN, KAS. — Research conducted at Kansas State University has shown that washing floor drains in food processing facilities may make it easier for Listeria monocytogenes to travel from the drain to processing operations. It is well known open floor drains in processing environments may harbor the bacteria, which is why the drains are the focus of high pressure washing and cleaning.
The K.S.U. researchers found that the aerosols generated by the washing may transfer the bacterial cells away from the drain and onto surfaces where food is being processed a few feet above the floor.
The situation may be remedied, but workers need to be trained how to do so, said Jasdeep Saini, a K.S.U. doctoral student in food science who researched the issue with food science professors James Marsden and Daniel Fung. The workers should then modify their cleaning procedures.
"If the worker who is actually doing that knows that this is the point from where the translocation of bacteria is actually occurring and is told to be careful, some change in that respect can be made," Ms. Saini said.
The research team ran tests to find out the potential for translocating L. monocytogenes from drains to food contact surfaces. The researchers placed stainless steel markers at heights of 1 feet, 3 feet and 5 feet above the drain level. They checked the markers after using a high-pressure hose to wash the drain and took samples after 8 hours and again after 48 hours.
The numbers for both the 8-hour and 48-hour tests showed that bacterial cells from the drain were found at all three height levels, the highest number at the 1-foot level closest to the drain. More bacterial cells were present on the contact surfaces after 48 hours than after 8 hours, likely because of the longer time available for the cells to proliferate and form a biofilm.
"Listeria has been known to form biofilms," Ms. Saini said. "Biofilms develop between 36 and 48 hours. If there are biofilms existing in the drain, how those are actually translocated can cause contamination on the line."
Floor drain cleaning procedures
On a daily or weekly basis:
• Move equipment or food-contact surfaces that may become contaminated during cleaning or use a splash guard.
• Remove drain cover and clean it with a brush.
• Rinse drain with low-pressure hose.
• Do not use high-pressure water hose, as it may cause splash-back of contaminants from drain.
• Foam drain with a detergent solution.
• Scrub drain with a brush (¼-inch to ½-inch smaller than the drain opening) using circular motion to prevent cross-contamination between the drain and the processing-area floors.
• While brushing, allow a low-pressure water hose to run around the drain to direct the scrubbed biofilm and organics down the drain.
• This action prevents biofilm from developing or strengthening itself by producing a glue-like material, which may result in protection of microorganism inside the biofilm "glue."
• Brushing in-pipes below drains should be done by using a circular motion with the brush, rather than an up-and-down motion. Using a circular motion with a brush will result in 360-degree coverage of the pipe below the drain. If an up-and-down brush motion is used, there is a danger of splash-back, and failure to remove biofilms and debris.
• After scrubbing, place the brush directly into a bucket containing a high concentration of sanitizer. Do not place the brush directly on the floor or in contact with any other surface prior to sanitizing.
• Rinse drain with low-pressure hose.
• Flood drain with sanitizer (4X recommended concentration).
• Insert antimicrobial block or ring if needed to continuously reduce microbial growth in drains.
• Replace drain cover.
• Clean and sanitize drain brush and let air dry.
Drain brush care:
• Sanitize brush in a bucket with a strong solution of quat (1,000 ppm).
• Wash brush thoroughly with cleaning solution in a bucket.
• Sanitize brush with a fresh solution of quat (1,000 ppm).
• Hang brush and let air dry.
In case of microbial problem (corrective action) daily procedure (for two weeks):
• Follow initial steps as above all the way through replacing drain cover.
• Prepare a solution of high-concentration sanitizer in a 5-gallon bucket.
• Pour the prepared solution into the drain all at once.
• Clean and sanitize drain brush, and let it air-dry.
• To prevent microbial problems in floor drains, or to solve a microbial problem that exists, a product like Zep Biofilm Drain Purge may be used in the drain. This product will break down the biofilm and flush the microorganisms inside down the drain, as well as clean out the insides of the drains.
The Floor drain cleaning procedures list is to be used only as a guideline. The list originally appeared in the April 2009 issue of MEAT&POULTRY Magazine, a sister publication of Sosland Publishing’s Food Safety Monitor.