The National Provisioner asked Edward Mills, associate professor of Dairy and Animal Science at Penn State University, for his thoughts on the multitude of options that processors face when choosing a sanitizer to clean their plants and equipment.

Q: Give a brief overview of sanitizers that are most useful to meat and poultry processors, from soaking foams to high-pressure sprays and any others that are used to clean equipment and other surfaces quickly and efficiently.

Mills: Cleaning and sanitizing meat plant equipment and facilities is the heart of a food-safety program. Processors see the benefits of their sanitation programs in negative Listeria, E. coli O157:H7 or other pathogen tests and in extended product shelf-life.  Achieving those low microbial numbers requires selection of the right chemicals and procedures and constant diligence in the daily cleaning operations. … In the past, it has been common to use high-pressure water to remove surface residue. This technique can be somewhat effective using cool or warm water where significant protein residue is present, and very hot water where primarily fat residue is present. However, with the use of an appropriate cleaning/detergent solution, one can greatly reduce the amount of water required in the cleaning process.

It is quite common to apply the cleaning solution as a foam in order to increase its effectiveness. Areas with heavy soil accumulation may be hand-scrubbed or re-treated with foam as needed. Finally, the foam is rinsed off with hot water. It may be necessary to use high-pressure water, but this should be avoided if possible as it tends to use more water, produce aerosols and spread contamination.

After rinsing the cleaning solution,the surface should be treated with a sanitizer. A no-rinse sanitizer such as chlorine might be used if the surface is to be used immediately. If the equipment or room is to be idle for some time, it may be preferable to apply a more durable sanitizer such as quaternary ammonium, which may need to be rinsed off later.

Q: How do sanitizers differ in their performance capabilities in different parts of a plant?

Mills: Choosing the correct sanitizer for a particular application is best done with the help of your chemical supplier. But you should come to the discussion with a good knowledge of the factors involved. In order to make the correct choice, you will need to consider the nature of the surface, the temperature and the exposure time. Surfaces should be kept smooth and free of cracks or irregularities that might harbor bacteria. Pools of water should be removed, as these will severely dilute the sanitizer. Surfaces must be thoroughly rinsed to remove any residue of the cleaning solution/detergent.

The antimicrobial effects of sanitizers are usually improved at higher temperatures. When applied to surfaces immediately following cleaning, the surfaces are often still warm from the hot water used. However, if the sanitizer is applied to cold surfaces, such as at startup of a line that has been idle, the effectiveness may be reduced, requiring increased concentration or contact time to achieve a satisfactory kill. As a general rule, a minimum of one minute exposure time should be allowed for non-rinse sanitizers on a warm surface. Recommendations by your chemical supplier obviously take precedent over any general statements made here.

Water quality also affects performance of sanitizers. Hard water may significantly reduce the effectiveness of quaternary ammonium sanitizers. Chlorine sanitizers are less affected by hard water but are very sensitive to presence of organic residues.

The effectiveness of sanitizers is affected by types of micro-organisms present. Sanitizers are generally effective against bacteria, the most common micro-organisms in most areas of the plant. However, in drier areas, such as store rooms, spores may be present, and yeasts, fungi or molds may be more common in aging rooms where products are held for an extended time. These micro-organisms may be resistant to some sanitizers.  

Q: How have CIP (clean-in-place) systems changed the way sanitizers are used?

Mills: Clean-in-place (CIP) systems are widely used in the dairy and beverage industries. With CIP, cleaning and sanitizing are completed without disassembling the equipment. A cleaning solution is pumped through the system, followed by a rinse solution and then a sanitizer. The approach is very desirable, because a minimum amount of water and cleaning chemicals are used. Labor requirements are also quite low. This approach works well in dairy and beverage industries, where product processing is mostly in a closed environment. However, it has not been widely used in the meat industry largely due to the complexity of the equipment and facilities used.

Nevertheless, CIP or some variation of it may be coming to the meat industry, as automated cleaning systems are already used for smokehouses, and automated washers are commonly used for vats, smoke trees and racks among others. Research is being conducted at Penn State and other universities to find ways to apply CIP principles to more complex equipment.

Q: What are some of the pitfalls processors must watch for when using sanitizers in their plants?

Mills: Chemicals used in cleaning and sanitizing are among the most caustic and corrosive materials found anywhere in a meat plant. Workers involved in cleaning and sanitation operations must be well-trained and carefully supervised to assure their safety as well as the effectiveness of the cleaning and sanitizing operations. In addition to worker safety, the chemicals used in cleaning and sanitation can be quite damaging to equipment and facilities. Care should be taken to protect sensitive electrical fixtures and avoid overuse of corrosive chemicals.

Q: Is there room for improvement as far as sanitizers go, in terms of effectiveness, ease of use, etc.?

Mills: In past years, much progress has been made in improving the chemistries of detergents and sanitizers used in the meat industry. I have little doubt that there are more improvements to come, especially in making the chemicals safer for workers and less destructive for equipment. Specialized enzymes capable of degrading specific soils without the need of strong acids or caustics are on the horizon. Specific antibacterials, such as bacteriocins, may become more important as sanitizers.

It is increasingly common to see detergents and sanitizers dispensed from mixing stations located near the site of use. This raises the prospect of more closely matching the chemicals used to the types of soil or micro-organisms to be controlled at a certain location. Instead of preparing a batch of sanitizer for the whole plant, one might prepare a small amount of sanitizer customized for a specific room or even a particular piece of equipment. NP