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From: Food Quality & Safety magazine, December/January 2010

Fight Pathogens and Microbes in Processing Areas

Following strict equipment cleaning and sanitizing regimens cuts safety risks

by Charles Giambrone, MS

Editor’s Note: This is the second article in a two-part series. Part one, “Critical Sanitation Issues in Food Service,” appeared in our October/November issue.

In part one of this article, we reviewed the evolution of food safety regulations for food service establishments. We discussed the critical sanitation issues found in food service operations, specifically addressing the zones that strongly affect key areas of the food service facility, namely zone 3, the immediate environmental zones around the food processing area, and zone 4, the general environment of the food plant. These areas are discussed in chapters five and six of the 2005 Food Code. In this article, we will focus on the lucrative targets for pathogen and spoilage microbes—the food processing areas of your food service operation.

Purchasing new or used equipment that adheres to the 2005 Food Code’s criteria and has National Sanitation Foundation (NSF) approval gives you a chance to properly clean and sanitize all food contact surfaces in your facility. No matter who approves the equipment, if you do not sanitize properly, the food safety risk will remain huge for your operation and your customers. We will now concentrate on some critical equipment sanitation issues.

Cutting Boards

First, let us focus on cutting boards and tables. If a facility requires a wood surface or utensil, it is important to select hardwoods. The daily manual sanitation regimen for cleaning wood surfaces must be impeccable, with good housekeeping during handling and processing.

Wood or NSF-approved plastic cutting boards can be placed in a dishwashing unit; this is the preferred cleaning method, because the chemical concentrations and water temperatures thoroughly clean the porous surface.

Several years ago, Arthur Miller and his colleagues in the U.S. Department of Agriculture’s Eastern Regional Research Center in Wyndmoor, Pa., compared how effectively various manual-cleaning regimens removed Escherichia coli 0157:H7 from hardwood cutting boards and polyethylene boards.1 Room temperature ground beef was placed on each cutting board type for a set period. The boards were swabbed, and the bacteria counted. The boards were cleaned, and the bacteria were counted again.

The study found that both surface types had comparable log reductions of the E. coli 0157:H7 strain. Moreover, while some hardwoods, like ash, had a slight inhibitory effect, the rest had little effect. In fact, hard maple food contact surfaces exhibited a slight increase in microbial numbers within the 30- to 90-minute time sampling periods. Some prior studies cited in this study found dishwashers were unable to remove target meat pathogens from the wood board, while others found that many woods have natural inhibitory effects against pathogens.

This study offers two takeaway messages. First, many variables influence sanitation efficacy on cutting boards, including the type of hardwood or the synthetic plastic polymer used. Second, as Miller recommended and I strongly concur: Any cutting surface used for food preparation is a critical control point, with the primary control being stringent, consistent sanitation.

Mixers and Blenders

There are many variations and sizes of mixers and blenders in food service operations. Some are the size of typical ribbon mixers/blenders found in large processing plants, and others are the size of typical home appliances.

Equipment scale determines whether the unit should be manually cleaned and sanitized. For small bench-top or home consumer-type units, use a three-compartment sink and color-coded brushes for all removable food contact components. I still prefer a small portable foam cleaning unit for table-top units, because coverage is more complete.

For larger floor-mounted units, foam clean and sanitize with applicable component tear down (e.g., mixing paddle/agitator blades). Manual cleaning is required for large floor-mount units. Whether your operation uses small home appliance units or large processing units, use the proper color-coded brushes, non-abrasive green pads that can be properly cleaned, or single-use fabric wipes. And as the Food Code admonishes, do not use sponges.

Kettles and Fryers

Stainless steel kettles can be cleaned with powder or foam cleansers.
Stainless steel kettles can be cleaned with powder or foam cleansers.

Table-top or floor-mounted kettles are usually constructed of stainless steel. Clean them with powder cleaners, and use the agitator blades to circulate the cleaner. Foam cleaners are also an option.

For fryers, a daily sanitation regimen is recommended, especially given the current use of unsaturated oils—like canola—that must be replaced quickly due to their short shelf life. As with any other high-heat surface, the pre-sanitation clean up preparation must be thorough and must include complete drainage of a warm—not hot—fryer, with complete removal of all ancillary parts, including baskets and strainers, for gross soil cleanup.

Clean-in-place (CIP) sanitation can be executed using a typical caustic-based, formulated cleaner designed for high-fat soils. Pre-application of a gel-based caustic product, coupled with additives in the CIP cleaner, can accelerate and optimize the fryer cleaning process. Fryer sanitation is important for product quality because an incomplete fryer sanitation procedure usually results in organoleptic issues with the fried food items.

Refrigerators and Holding Coolers

Temperature-controlled storage equipment units such as refrigerators and holding coolers can easily become niches for Listeria and various fungi. This tendency is mostly attributable to both poor hygienic design of the units and poor good manufacturing practices (GMPs), including improper sanitation.

Again, due to the different design and capacity ranges of walk-in coolers, sanitation issues will vary. The same can be said for reach-in type coolers, which can be under-the-counter, standard upright, or pass-through types.

Again, due to the different design and capacity ranges of walk-in coolers, sanitation issues will vary. The same can be said for reach-in type coolers, which can be under-the-counter, standard upright, or pass-through types. The smaller units must be manually cleaned and sanitized, with the subcomponent sanitation done in the three-compartment sink or the dishwasher.

Because of their accessibility, larger walk-in units can be foam cleaned as well as fog sanitized, with workers paying careful attention to a variety of factors.

The clutter and congestion that develop in these small to large holding coolers make it difficult to maintain a proper hygiene level. A lack of proper drains or poorly maintained drains, a lack of periodic maintenance, and poor sanitation of the cooler ceilings, walls, and floors are typical weak links in these coolers.

These internal structures must be constructed of smooth, non-porous surfaces that are chemically resistant and readily cleanable. Many larger walk-in coolers have strip curtains to conserve energy and prevent air loss. Because these strip curtains are potential cross-contamination niches, however, they must be on a strict periodic maintenance and sanitation schedule.

Walk-in refrigerators can be foam cleaned and fog sanitized.
Walk-in refrigerators can be foam cleaned and fog sanitized.

Proper specific AC unit maintenance and sanitization must be addressed with a well-maintained cooler with a periodic maintenance program. This includes fogging disinfection of the interior of the cooler to circulate disinfectant through the coils and fans of the coolers’ AC units. Also, the drip pans must be on a set periodic maintenance sanitation frequency, with easily accessible, removable drip pans, proper use of sanitizer blocks, and proper pitch of the drip pans and controlled drip pan drainage into the floor drain.

Slicers, Choppers, and Grinders

Slicers, choppers, and grinders are used for both raw and ready-to-eat (RTE) products. Some smaller operations can use one unit for both, provided that RTE product goes through the unit first and assuming there are no allergen transfer issues. The strong preference in a food service establishment, however, is to have dedicated, segregated slicers, choppers, and grinders for raw and cooked foods.

All three types of equipment have many moving parts and a large surface area that requires cleaning and sanitizing. Clean the bench top of larger choppers and grinders between each use if the room is not refrigerated. If the prep room is refrigerated and is a low-humidity, low-moisture environment, and assuming the same food product is being processed, only daily sanitation is required.

Remove, manually clean, and sanitize all subcomponent blades, grinder plates, and removable impellers in a three-compartment sink, dishwasher, or clean-out-of-place (COP) tank. After thorough sani- tation, carefully reassemble all detachable parts under proper GMPs. Again, some of these units have excellent hygienic designs and are rated by the NSF or Underwriters Laboratories Inc., while older units have a lot of hygienic design issues and are challenging to sanitize.

Most dishwashing units do an excellent job, provided the food service operator properly designs, uses, and maintains them.
Most dishwashing units do an excellent job, provided the food service operator properly designs, uses, and maintains them.

Slicers are in a whole realm by themselves and are used in the entire range of food service operations, from the tiny restaurant or deli to the large-scale food service plant. Trade groups and regulatory authorities have spent a lot of time and effort describing proper GMPs and sanitation procedures, because slicers are tremendous cross-contamination vectors with RTE products.

With respect to proper GMPs affecting food safety, a dedicated slicer (e.g., for RTE meat products), stored under proper refrigeration, can be cleaned daily. At roughly 50°F to 55°F, the Food Code requires a 10-hour sanitation frequency. If your slicer is kept at ambient temperatures, especially if it is used for warm to hot moist RTE products, more frequent sanitation is needed. The Food Code prescribes a four-hour cleaning frequency under these criteria.

The sanitation frequency for a slicer is dependent upon the product type, the environmental conditions, and the proper validation environmental sanitation studies (e.g., ATP and microbial indicator swabs). A typical modern slicer has many components that can be removed for proper sanitation, including the meat holders/grips, chutes, and knife guards. Manually clean and sanitize these components or wash them in a dishwasher.

The most troublesome component is the slicer blade. Most current commercial units do not have a removable blade to facilitate proper sanitation. Careful manual cleaning and sanitizing, wiping from the center of the blade to the edges, is necessary.

In 2006, Mike Doyle and colleagues at the Center for Food Safety at the University of Georgia, under the initiative of the American Meat Institute’s Equipment Design Task Force, conducted a comprehensive study of the sanitary design of meat slicers for better cleanability.2 One of the critical subcomponents for sanitation, namely meat holders/grips, varied in their hygienic design. The better designed components were removable, had fewer grip teeth, and had more grease-resistant food contact surfaces. This rule applied to guard rings, as well. Also, in components like blade covers, chutes, and carriage trays, those with flat, smooth, grease-resistant surfaces were far easier to clean and sanitize.

HVAC Issues and Concerns

Food service kitchen ventilation for the general environs and specifically for the hoods used in cooking zones (stoves, ovens, and fryers) must be hygienically maintained to avoid cross-contamination issues. Airborne microbes can and will wreak havoc upon your food service operations.

Purchasing new or used equipment that adheres to the 2005 Food Code’s criteria and has National Sanitation Foundation approval gives you a chance to properly clean and sanitize all food contact surfaces in your facility.

First, let us discuss the general environmental airflow and its parameters. Ideally, any cooking or post-cooking food-handling zone should be under positive pressure to prevent airborne contaminants from entering the critical product processing and handling zones of the operation.

Maintain a strict periodic maintenance sanitation schedule for the HVAC system so that it can properly filter out chemical, physical, and microbial airborne contaminants, while preserving all food handling and processing zones under their optimal temperature and humidity. This applies both for a facility’s perishable storage rooms, its refrigerators and freezers, as well as for the general food handling environs.

Ventilation hood systems, typically constructed with durable food-grade stainless, must be cleaned with aggressive, robust foam or gel cleaners with a higher level of caustic that can cut through the carbonized soils and grease that typically accumulate on these units.

Perform hood sanitation daily to avoid problematic carbonized grease buildup. Sanitize the filter units weekly, preferably using a dishwashing or COP tank, or, if those are unavailable, the three-compartment sink. Hood sanitation is important for another reason: Poor sanitation has resulted in numerous grease fires in food service facilities due to a heavy filter and hood duct grease accumulation.

Critical Sanitation Tools

Although many of us are familiar with the proper design and chemical dispensing systems for three-compartment sinks, we still see many of them improperly used in food retail, service, and processing facilities. Although the Food Code defines specific, restricted scenarios in which a two-compartment unit is appropriate for manual cleaning, the three-compartment sink must be the standard.

The first compartment, the wash compartment, should have a minimum water temperature of 110°F (43°C) with a ? ounce to 1 ounce per gallon auto-dosed concentration of a typical detergent approved for manual sanitation. I recommend a typical wall-mount venturi auto dose to prevent detergent misuse. Soak the items for three to five minutes, then perform proper mechanical agitation with a white long-handled scrub brush.

All components of a three-compartment sink should be manually cleaned and sanitized.
All components of a three-compartment sink should be manually cleaned and sanitized.

The second compartment is the rinse compartment. Although clean rinse water that is at least the same temperature as the wash water is acceptable, optimal rinse water temperature is somewhat higher. Once the rinse water is soiled, replace it. Some operations leave the rinse compartment empty and rely on a spray nozzle instead for thorough rinsing. Because rinse water temperature can approach 140°F, the operator should wear chemically and thermally resistant lined gloves and safety glasses.

The third compartment, the sanitizer compartment, should have a D2-rated (old USDA system), NSF-approved sanitizer at an Environmental Protection Agency (EPA)-approved food contact concentration for a one-minute immersion sanitizing period. As with the detergent in compartment one, the sanitizer should be auto-dosed and verified using appropriate test strips and titration kits to ensure that the sanitizer is at a proper no-rinse, EPA label-approved concentration.

Many varieties of mechanical dishwashers are used in food service operations, ranging from classic, single-tank, home-type dishwashers to manually loaded flight-type continuous units to automatic conveyor rack units that have auto-dispensed detergent to carousel closed loop systems and automatic immersion units. Some units use a sanitizer dosing as well to reduce required wash temperatures, but many rely on hot water rinses. Also, these types of units should have a heat boost pump to dose a hot final rinse for the high temperature-type units. The auto dispensing feature of the detergent must be properly maintained as well.

Most dishwashing units, whether old or new designs, do an excellent job, provided the food service operator properly designs, uses, and maintains them. The dishwasher type used in a food service operation should be compatible with the facility’s design. The NSF has many approved standards for all unit varieties.

Some key issues concerning dishwashing units include incomplete removal of excess soil; improper detergent concentration; water temperature; cleaning/rinse cycle time; improper racking, which applies especially to single-tank systems; untreated hard water leaving films; and streaking due to excessive detergent or lack of rinse aid. ■

Giambrone is senior technical support manager at Rochester Midland Corp. and is also a qualified SQF consultant. Reach him at


  1. Miller AJ, Brown T, Call JE. Comparison of wooden and polyethylene cutting boards: potential for the attachment and removal of bacteria from ground beef. J Food Protection. 1996;59(8):854-858.
  2. Zhang G, Ma L, Doyle MP. Sanitary design of meat slicers for better cleanability. Research project from the Center for Food Safety, College of Agricultural and Environmental Sciences, University of Georgia; 2006; Griffin, Ga.
  3. McSwane D, Rue NR, Linton R. Essentials of Food Safety and Sanitation. Upper Saddle River, N.J.: Prentice Hall; 1998.
  4. Marriott NG. Principles of Food Sanitation. 4th ed. Gaithersburg, Md.: Aspen Publishers Inc.; 1999.
  5. U.S. Food and Drug Administration. FDA 2005 Food Code: Chapter 4, Equipment, Utensils, and Linens. FDA. Available at: Accessed November 15, 2009.



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