According to the “Principles of Food Sanitation,” by Norman G. Marriott and Robert B. Gravani, the optimal cleaning system in meat and poultry plants depends on the type of soil and type of equipment present. High-pressure, low-volume cleaning equipment is normally the most effective for removing heavy organic soil, especially when deposits are located in areas that are difficult to reach and penetrate. However, foam, slurry and gel cleaning have become more prominent because cleaning is quicker and cleaners are easier to apply using these media.

In meat and poultry plants, acid cleaning compounds are used most frequently to remove mineral deposits. Organic soils are more effectively removed through the use of alkaline cleaning compounds. Chlorine compounds provide the most effective and least expensive sanitizer for destruction of residual microorganisms. However, iodine compounds give less corrosion and irritation, and quaternary ammonium sanitizers have more of a residual effect. Appropriate cleaning procedures depend on the area, equipment, and type of soil.

Properties of food soils

As stated by Ronald H. Schmidt, Ph.D., professor and food science and human nutrition for University of Florida, Gainesville, food soil is generally defined as unwanted matter on food-contact surfaces. Soil is visible or invisible. The primary source of soil is from the food product being handled. However, minerals from water residue and residues from cleaning compounds contribute to films left on surfaces. Microbiological biofilms also contribute to the soil buildup on surfaces.

Under certain conditions, microorgranisms (bacteria, yeasts and molds) can form invisible biofilms on surfaces. These can be difficult to remove and usually require cleaners as well as sanitizers with strong oxidizing properties.

A leading provider of specialty chemicals and cleaning solutions recently introduced an EPA-approved product for destroying biofilm coatings found in food-processing area drains and plumbing. Biofilms protect and harbor Salmonella, E. coli, Listeria and many other pathogens, which cause deadly illnesses, and this new product removes the biofilm and kills these resistant microorganisms in hard to reach places.

Not surprisingly, the USDA has reported that 28 percent of food-processing area floors and drains tested positive for Listeria alone.

Since soils vary widely in composition, no one detergent is capable of removing all types, Schmidt says. Many complex films contain combinations of food components, surface oil or dust, insoluble cleaner components, and insoluble hard-water salts. These films vary in their solubility properties depending upon such factors as heat effect, age, dryness and time.

Methods of sanitization

The objective of sanitizing food-contact surfaces is to remove the food (nutrients) that bacteria need to grow, and to kill those bacteria that are present. It is important that the clean, sanitized equipment and surfaces drain dry and are stored dry to prevent bacteria growth. Necessary equipment (brushes, etc.) must also be clean and stored in a clean, sanitary manner.

In terms of sanitizing, Schmidt says it is important to differentiate and define certain terminology. For example, to sterilize, refers to the statistical destruction and removal of all living organisms; to disinfect, refers to inanimate objects and the destruction of all vegetative cells (not spores); and to sanitize, refers to the reduction of microorganisms to levels considered safe from a public health viewpoint. Appropriate and approved sanitization procedures are processes and, thus, the duration or time as well as the chemical conditions must be described. The official definition (Association of Official Analytical Chemists) of sanitizing for food-product contact surfaces is a process which reduces the contamination level by 99.999 percent (5 log) in 30 seconds. The official definition for non-product contact surfaces requires a contamination reduction of 99.9 percent (3 log). The standard test organisms used are S. aureus and E. coli.

General types of sanitization include thermal sanitization, which involves the use of hot water or steam for a specified temperature and contact time; and chemical sanitization, which involves the use of an approved chemical sanitizer at a specified concentration and contact time.

In food-handling operations, chemical sanitizers are used as rinses, sprayed onto surfaces or circulated through equipment in CIP operations. In certain applications, the chemicals are foamed on a surface or fogged into the air to reduce airborne contamination. Some of these chemical sanitizers include chlorine-based sanitizers such as chlorine compounds and chlorine dioxide, iodine, quaternary ammonium compounds, acid-anionic and fatty-acid sanitizers, peroxides and peroxyacetic acid.

Sanitizing savvy

The National Provisioner bends the ear of Norman G. Marriott, Ph.D., emeritus professor of food science for Virginia Tech., and co-author of the “Principles of Food Sanitation,” about the sanitation needs of today’s meat and poultry processors.

The National Provisioner (NP): In the never-ending battle to safeguard the meat and poultry industry’s manufacturing plants from contaminants, manufacturers are constantly developing new ways to help processors enhance food safety. What type of sanitizing systems specific to meat and poultry processing are out there?

Norman G. Marriott:Most firms that manufacture cleaning compounds and sanitizers provide off-the-shelf and custom-designed sanitizing equipment. Large-volume operations will benefit more from custom-designed sanitizing equipment, but the cost is significantly higher.

NP: What types of cleaning and sanitizing compounds are used to clean the actual equipment?

Marriott:Most cleaning compounds are heavy-duty alkaline cleaners, although stronger acid-cleaning compounds may be needed where encrusted surface materials and mineral-scale deposits exist. Furthermore, strong alkaline cleaners are needed to remove very heavy soils such as those in a smokehouse. These names are generic. Chemical companies have their own trade names for these generic cleaners.

NP: What types of sanitizing systems and equipment are used in today’s meat and poultry plants?

Marriott:Sanitizers can be applied as a spray, mist, foam or through flooding the equipment or area with a sanitizer. Furthermore, cleaning-in-place (CIP) and cleaning-out-of-place (COP) equipment can be designed to sanitize equipment being cleaned.

NP: These sanitation systems must be in place for use by personnel working along a food-processing line, but how is this enforced?

Marriott:The major source of enforcement is through effective supervision. However, sprays, foams, footbaths and hand sanitizers can be installed to provide required sanitizing when entering work areas.

Chemical sanitizing

According to Ronald H. Schmidt, Ph.D., professor and food science and human nutrition for University of Florida, Gainesville, the ideal chemical sanitizer should:
  • Be approved for food-contact surface application
  • Have a wide range or scope of activity.
  • Destroy microorganisms rapidly.
  • Be stable under all types of conditions.
  • Be tolerant of a broad range of environmental conditions.
  • Be readily solubilized and possess some detergency.
  • Be low in toxicity and corrosivity.
  • Be inexpensive.
No available sanitizer meets all of the above criteria. Therefore, it is important to evaluate the properties, advantages and disadvantages of available sanitizers for each specific application.