Dry Cleaning

In dry processing plants, dry cleaning and sanitizing practices are a necessity, but the process can be just as beneficial for many areas of wet processing plants as well. While introducing water into a low-moisture production area can adulterate the product, cause mold, and affect product shelf life, reducing water in other environments also can increase food safety.

Essentially, said Best Sanitizers Regional Sales Manager Harry Reeder, “dry cleaning is processes and procedures that exclude the use of water.”

Reducing water reduces the mobility of pathogens which reduces their viability, said Biomist Vice President Rob Cook. “Salmonella can lie dormant for months, then water can bring it to life.”

Reeder agreed, noting, “The majority of microorganisms are composed of 80 percent water, so they reproduce best in environments where moisture is present.” So, he added, “if you eliminate moisture, you are eliminating one of the elements they need to proliferate.”
 

In the Zone.

Dry cleaning is used primarily in zones 1 to 3 (food contact surfaces to areas outside the areas around food contact surfaces). The first step is physical removal of food remnants, debris, and other contaminants from food and non-food surfaces by vacuuming, brushing, sweeping, scraping, or otherwise abrading the surface. Following that, an alcohol-based quaternary-ammonium compound is applied to the surfaces as a sanitizing kill step. Alcohol-based compounds dry very fast after application, Cook explained. (See 7 Steps of Dry Cleaning at right for the full process.)

In some plants, the dry cleaning process begins with blowing of high-pressure air from top to bottom of the area, Reeder said, after which the contact surfaces are wiped or sprayed with an alcohol-based surface sanitizer.

“It all circles back around to: How do you keep moisture out of the plant?” Reeder said. “Listeria, Salmonella, Clostridium, E. coli, Staphylococcus—all come from environmental conditions such as soil, water or fecal matter, and one of the commonalities in all of these is moisture.”
 

Dry Cleaning Benefits.

In addition to reducing moisture in a plant, dry cleaning can reduce the cleaning and sanitation downtime of a plant. “Many products are compromised by water, so if you have to wait for a surface to dry before running a production line, you are losing productivity and creating downtime,” said United Sanitizing Founder Chuck Carman. This is particularly true of equipment sections such as belts that can take a long time to dry.

Because alcohol-based products can be used right before a run with little to no wait, a line that has been sitting—and susceptible to contamination from airborne particles—can be sprayed just prior to operation and within five minutes be ready to run, Cook added. No rinsing is needed for USDA D2-rated sanitizers, and the alcohol evaporates quickly, leaving the surface ready to use.

An additional benefit of dry cleaning is the environmental aspect of less product and waste and reduced labor. When rinsed, a high proportion of a wet cleaner or sanitizer is washed down the drain, but dry sanitizers are transferred directly to the surface and evaporates on its own without rinsing, Carman said. “The goal is to apply an even mist of sanitizer where it is needed without waste. Proper contact time is achieved automatically via fast self drying, so labor expense from wiping is eliminated.”

Dry cleaning and sanitizing methods also can be used on electrical components and electronic equipment that cannot withstand water, and maintenance personnel also may dry clean and sanitize tools this way, not only to protect them from water-based cleaners that could cause corrosion, but also because the tools can be quickly sanitized then used in another area without having to wait through a water-based cleaner dry time.

In wet processing plants, dry cleaning is sometimes used on a rotational basis. Some plants will periodically rotate sanitizers to avoid resistant strains of bacteria from developing, Reeder said. For example, he said, a plant may use a quaternary compound, then switch to a peracetic acid, then use an alcohol-based sanitizer, then start over again with the quat.

While zones 1 to 3 tend to be the primary areas in which dry cleaning is used, you shouldn’t limit your thinking of the process as useful only in production areas, Carman said. Use dry cleaning and sanitizing as a preventive system in between zones, in areas where employees are taking a break, and on shared items that cross zones—such as radios, shoes, and even incoming delivery vehicles.

“You can expand the spectrum of things you can sanitize, and that can have a positive impact on your operations,” Cook said.

The author is Editor of QA magazine. She can be reached at llupo@gie.net