By Mike Kohler
Technical Scheme Lead, Product Certification, Food Retail
NSF
Foodborne illnesses pose a serious risk to restaurant operators. Outbreaks can turn off regular customers and draw increased scrutiny from public health officials, sometimes leading to closures. While sick employees are the leading spreaders of foodborne illnesses (about 40 percent of cases, according to the Centers for Disease Control), poor sanitation can also be a contributing factor. Even if a patron doesn’t get sick, no one wants to eat off an unclean plate.
Since the introduction of its first food equipment sanitation standards in the 1950s, NSF has certified thousands of products for use in restaurant and commercial kitchens. The product testing and inspection organization continues to evolve those standards to include requirements for material safety, design, construction and product performance.
In this recurring column, foodservice equipment manufacturers and dealers can learn more about NSF/ANSI food equipment standards and how they support food safety. This issue will review standards for commercial warewashing equipment.
Explaining the NSF/ANSI 3 Standard
NSF/ANSI 3: Commercial Warewashing Equipment establishes minimum public health and sanitation requirements for the materials, design, construction and performance of commercial warewashing machines and their related components.
NSF/ANSI 3 was first published in 1953. Its performance requirements were originally based on minimum specifications for spray times, water temperatures and water volumes. The spray exposure time for wash and rinse processes, water temperatures used during those times and water volumes are directly proportional to cleaning and sanitizing results. Therefore, the earlier versions of NSF/ANSI 3 established the minimum times, temperatures and volumes that were considered sufficient.
In more recent times, the desire and need to conserve resources became important and the standard evolved as a result. Performance tests for measuring the actual removal of soil and tests to quantify heat accumulation on dishes were added as replacements for specific minimum spray times and water volume specifications. These revisions allowed manufacturers to design machines that use less water but still meet acceptable criteria for cleaning and sanitizing wares. Minimum water temperature criteria were maintained in alignment with the U.S. Food and Drug Administration (FDA) Food Code.
Testing Requirements
The testing requirements for NSF/ANSI 3 vary depending on the type of warewashing machine. The standard covers various machine types depending on the wares the machine is designed to wash and sanitize, the rack configuration the machine uses and the sanitizing means.
The basic machine types in the current standard include dishwashing machines, glasswashing machines and pot-pan-and-utensil washing machines.
- Dishwashing machines are designed to clean and sanitize dishes, glasses and utensils.
- Glasswashing machines are designed to clean and sanitize only glasses.
- Pot-pan-and-utensil washing machines are designed to clean and sanitize pots, pans and cooking utensils.
Each of the basic machine types may be a stationary rack design or a conveyor design. Stationary rack machines apply sequential wash and rinse sprays for specified times to a stationary rack of wares within the machine. Conveyor machines move wares through a series of wash and rinse sprays at a specified speed; either on a dishrack (rack conveyor machine) or with wares directly on a conveyor belt (rackless conveyor machine).
Another factor in how warewashing machines are categorized is how sanitizing is accomplished. The machine type could either be hot water sanitizing (high-temp machine) or chemical sanitizing (low-temp machine). Hot water sanitizing machines rely entirely on heat from water to achieve sanitization. Chemical sanitizing machines rely on chemical solutions to achieve sanitization. Some machines are designed with a dual sanitizing mode, operating as a hot water sanitizing or a chemical sanitizing machine.
Soil Removal Tests
Soil removal tests are used to determine the cleaning ability of all machines. For dishwashing and glasswashing machines, the test method involves applying a coat of buttermilk (1 percent milkfat) to the surfaces of the wares, which are then allowed to air dry at 100 degrees Fahrenheit (37 degrees Celsius) for 17 hours. The wares are arranged in the racks or directly on the conveyor according to test patterns shown in the standard for the specific machine design. Following the test, the surface of the plates and glasses are visually inspected for any remaining buttermilk or detergent.
The soil removal efficacy of pot-pan-and-utensil washing machines involves observing the machine’s ability to remove a baked coating of pie filling from the surface of cookware. The soiled cookware is placed inverted on a rack in a 200 degrees Fahrenheit (93 degrees Celsius) oven and baked for one hour. The cookware is then cooled to room temperature before being arranged in the machine. After the machine is operated for a complete washing cycle in accordance with the manufacturer’s instructions, the surfaces of the cookware are visually inspected for any remaining pie filling or detergent.
Evaluating Sanitation Efficacy
Heat Unit Equivalents (HUE) tests are used to determine sanitization efficacy for hot water sanitizing machines. HUE testing involves measuring the surface temperature of applicable wares each second of the wash and rinse duration of hot water sanitizing machines. Each temperature recorded is converted to a heat sanitization value that corresponds to a time-temperature relationship used for heat pasteurization. The standard requires a minimum of 3,600 HUEs to be achieved.
Chemical sanitizing warewashing machines rely on the injection of chemical sanitizer in the final rinse water at a specified concentration. A chlorine chemical sanitizing rinse with a concentration of 50 parts per million (ppm) sprayed on the wares for a minimum of seven seconds is known to achieve adequate sanitization. If the machine is designed to use other chemical sanitizers besides chlorine, a bacteriological swab test is required to verify the efficacy of the recommended sanitizer for each unique machine design. The swab test involves inoculating applicable wares with E. coli, running them through the sanitizing cycle of the machine and swabbing the surfaces. A minimum 99.999 percent reduction (log10 reduction ≥ 5) is required to be achieved.
Picking the Right Machine
Since there are multiple factors for different types of machines, it is critical to pick the correct machine for the job and operate it as intended. NSF/ANSI 3 requires all testing to be performed at the lowest operational settings for the machine (shortest cycle times and lowest water temperatures). Therefore, important operating conditions must be displayed on the machine data plate or label. The required information includes minimum cycle times for wash and rinse, minimum water temperature for wash and rinse, chemical sanitizer type and minimum concentration, and flow pressure of the rinse water line. NSF Certification Listings for Commercial Warewashing Equipment also indicate details of the machine type, method of sanitization, cycle times or conveyor speeds the testing and certification are based on.
For more information about NSF/ANSI 3, visit www.nsf.org/food-equipment.