1.2 Food Facility Design & Sanitation

Food Facility Design & Sanitation

Core Principle: Proper facility design is the foundation of food safety. A well-designed physical space inherently prevents cross-contamination, facilitates effective cleaning, and excludes pests.

As a Registered Environmental Health Specialist (REHS), assessing a food facility extends far beyond inspecting food items; it involves evaluating the structural and mechanical environment where food is processed. This includes the logical progression of food through the space, the adequacy of illumination, the proper design of plumbing systems to protect the water supply, and the procedures used to sanitize equipment.

Facility Layout & Linear Flow

A fundamental concept in food facility design is the linear flow of food. The flow must progress in a single, unidirectional path from receiving to storage, preparation, cooking, and finally service. This movement minimizes the risk of cross-contamination by ensuring that raw, contaminated ingredients do not cross paths with ready-to-eat foods or sanitized equipment.

Segregation of tasks and areas is critical:

• Task Segregation: A separate prep sink must be designated for washing raw produce, apart from the sink used for thawing raw poultry or meats.
• Area Segregation: Clean areas and dirty areas (like dishwashing stations or garbage sorting zones) must be physically separated to prevent the aerosolization of contaminants onto clean dishes or food surfaces.

Lighting Requirements

Lighting intensity is measured in foot-candles (ft-c) or lux. Adequate lighting is crucial for employees to accurately read labels, monitor cooking temperatures, and identify dirt, grease, or pests during cleaning. The FDA Food Code mandates specific lighting minimums based on the activity in the area:

• 50 foot-candles (540 lux): Required in areas where detailed work is performed, primarily in food preparation areas where employees are working with knives, slicers, or inspecting food for safety.
• 20 foot-candles (215 lux): Required in consumer self-service areas like buffets and salad bars, inside equipment like reach-in refrigerators, in handwashing and warewashing areas, in equipment and utensil storage areas, and in restrooms.
• 10 foot-candles (108 lux): Required in less critical areas, including dry storage rooms, inside walk-in refrigerators and freezers, and in dining rooms during cleaning operations.

Additionally, shatter-resistant bulbs or protective shields must be installed over areas where open food is stored or prepared to prevent physical contamination from broken glass.

Warewashing Systems

Effective warewashing involves removing soil and significantly reducing the number of microorganisms on food-contact surfaces. The manual process typically utilizes a 3-compartment sink. The steps must be followed sequentially:

1. Scraping/Pre-rinsing: Removing gross food particles to prevent the wash water from becoming excessively soiled and depleting detergent.
2. Washing (1st Compartment): Using water at a minimum temperature of 110°F with an appropriate detergent to remove fats and soils.
3. Rinsing (2nd Compartment): Using clean water to remove detergent residue, which can interfere with the chemical sanitizing agent in the next step.
4. Sanitizing (3rd Compartment): Reducing pathogens to safe levels.
5. Air Drying: Items must be completely air-dried on a drainboard. Towel drying is prohibited as it can recontaminate surfaces.

Sanitizing Methods

Sanitizing can be achieved through hot water or chemicals. A test kit must be available to verify chemical concentrations.

• Hot Water Sanitization: Water in the sanitizing compartment must be maintained at 171°F or higher, and items must be immersed for at least 30 seconds. (Note: Mechanical high-temp dishwashers must have a final sanitizing rinse of at least 180°F, or 165°F for stationary rack, single-temperature machines).
• Chemical Sanitization: The effectiveness depends on concentration, temperature, and contact time.
  • Chlorine: Requires 50-100 ppm concentration. At a water temperature of 100°F (pH 10 or less) or 75°F-120°F (pH 8 or less), the required contact time is 7 seconds.
  • Iodine: Requires 12.5-25 ppm concentration. Minimum water temperature is 68°F. The required contact time is 30 seconds.
  • Quaternary Ammonium (Quats): Requires typically 200 ppm (per manufacturer instructions). Minimum water temperature is 75°F. The required contact time is 30 seconds.

Backflow Prevention

Cross-connections are physical links between safe (potable) water and dirty (non-potable) water. Backflow occurs when pressure differences cause contaminated water to flow backward into the potable water supply. This happens via backsiphonage (a vacuum created in the supply, pulling water backward) or backpressure (downstream pressure exceeds supply pressure, pushing water backward).

Plumbing codes and the FDA Food Code mandate protection against backflow:

• Air Gap: The most reliable form of backflow prevention. It is a physical, unobstructed vertical space between the water supply outlet and the flood rim of a receptacle. The air gap must be at least twice the diameter of the water supply pipe, but never less than 1 inch.
• Atmospheric Vacuum Breakers (AVB): Used on connections subjected to atmospheric pressure only (no valves downstream). Must be installed vertically downstream of the last shutoff valve.
• Pressure Vacuum Breakers (PVB): Can be used under continuous pressure but not backpressure.
• Reduced Pressure Zone Assembly (RPZ): Protects against both backsiphonage and backpressure. It is a complex mechanical device that requires regular testing and certification.

Pest Exclusion

Integrated Pest Management (IPM) focuses heavily on exclusion—preventing pests from entering the facility in the first place. Sanitarians must rigorously inspect the building envelope for vulnerabilities.

• Ensure all exterior doors are self-closing and tight-fitting with door sweeps installed to seal gaps along the threshold.
• Fill structural cracks, crevices, and pipe penetrations with copper mesh and sealant. Steel wool should be avoided as it rusts and degrades.
• Utilize air curtains (fly fans) above high-traffic delivery doors to blow a steady stream of air downward, preventing flying insects from entering.
• Ensure windows are covered with tight-fitting screens (at least 16 mesh per square inch) to keep mosquitoes and flies out.