In order to produce safe food manufacturer or food business operator adopt, follow, and sustain good manufacturing practices and HACCP to produce safe food for consumers. Did you know? The starting point or fundamental of food safety majorly resides at your facility. Yes, h Product contamination may occur not only at equipment level but also at the factory level. Therefore, design and construction of food processing and handling area in a hygienic way become an indispensable requirement. Hygienic design deals with details of hygienic design and construction of the physical structure and surrounding. An engineered design of food handling, processing, storage facilities and equipment to create a sanitary processing environment and to produce pure, uncontaminated, quality products consistently, reliably and economically (H.L.M. Lelieveld)
There is numerous consideration of design to be given when constructing a new grassroots or amending food processing facility to the great extent to control chemical, physical and microbiological hazard directly or indirectly. In generally the processing facility areas are differentiated into two broad categories i.e. external and internal.
Site Selection: Hygiene starts with location selection. Law says ideally food establishment need to be located away from pollution and produce disagreeable or obnoxious odours, fumes, chemical and biological emissions. For example, if the facility to process meat, poultry, vegetable oils (high-fat contents) then the site surrounding relatively odourless since fat is flavour carrier and will pick up odour cause off-flavour easily.
The site should have adequate of a source of potable (human consumption) water throughout the year even for future expansion.
- The incoming water line designed for adequate volume and pressure as desired.
- If pressure not sufficient than storage tank and booster pumps would be required.
- Water storage tank constructed in such a way to avoid the possibility biological contamination and enhance cleaning and sanitization.
- An adequate supply of cold and hot water provision to be made available as desired to adhere good manufacturing practices.
Landscaping: Sanitary landscaping is one of important barrier controller of rodents and keeping dust to a minimum.
- The processing facility surrounding area shall have grass free strip and lined up with a thick poly liner to keep weeds down and then filled pea gravel.
- The walking area and driving area shall be surfaced with concrete, that has been effectively treated to minimize dust, facilitate maintenance
- Tree around the plant is not recommended since they provide roosting and nesting spots for birds. If require trees, it is recommended to away from 30-40 feet.
Roof Area: Roofs are the equally important area as like the processing area. However, it is often ignored when it comes to sanitary design. It can be a major source of contaminants, especially if they are constructed of un-cleanable material i.e. tarpaper gravel (H.L.M. Lelieveld). There could chance of vegetation formation ranging from bits of grass and weeds. Some of the parameter to be considered at the time of roof selection are:
- Drainable and cleanable
- Discourage water accumulation
- Designed with downspouts to handle rain water.
- All openings through the roof are curbed and flashed
- The curb should extend 12 inches (0.3 m) or more above the finished roof
- Do not place insulation on the inside of the curb wall, as it is difficult to clean and frequently becomes infested with insects
- Roof penetrations for vents, intakes, oven vents, air-handling systems and some utilities must be sealed to prevent water leakage and subsequent interior air and surface
External lighting: Selecting and positioning appropriate light and location are essential in order to maintain the hygienic environment. As many of us know that light can be insect attractant, especially those that emit a high level of ultraviolet light. Where ever possible, it is suggested to the position about 30 feet (9 Meter away). Recommended light for the external area is high-pressure sodium lights, as they have a whiter light, low UV, and use less energy.
Appropriate layout: Interior of the food processing facility must be designed hygienically so that the flow of material, people, air, and waste can proceed in the right directions. Some of the important for the appropriate layouts are:
The flow of material needs to be in one direction. Logically it shall follow the sequence of operation i.e. receiving raw material …… and finally dispatch finished products.
- Barrier or separation to be created between clean and unclean area
- Workflow needs to be smooth and to extent possibly straight with minimal crisscrossing
- Flow of food waste and discarded material shall be in the opposite direction
- To extent possible designed to minimize non-essential personal traffic from passing through the processing and packing area.
Floor: The floor is the most important part of food processing area. Needless to say, it is the most abused part in food processing area such as chemical, water, dust, cleaners, sanitizers, acid, lubricant, food particles, dropped equipment, tools pallet dragging, temperature, hot water or cooking oil foot traffic, forklift and pallet jack traffic. Therefore floor shall be selected considering all above to withstand all kind of abuse i.e. durable, smooth and easy to clean.
- Monolithic coating at processing and production area – seen as good flooring material
- Floors should be sloped toward drains and provided with curbed wall floor junctions, with the curbs having a 30-degree slope to prevent accumulation of water, dust or soil.
- Concrete flooring is not recommended for high-care production areas, because it can spill and absorb water and nutrients, allowing microbial growth below the surface.
- Wall – floor junctions to have a smooth rounded finish for ease of cleaning.
Walls: Wall requirements greatly vary depends on the location i.e. external and internal. Requirement of external walls are:
- Water, rodent and insect proof
- Light density or cinder blocks not recommended as they are porous and encourage pest / insect infestation / harbourage.
- All wall penetration for wiring, plumbing, ventilation, and utility pipes shall be framed and sealed with metal or galvanized hardware cloth to withstand rodent gnawing
- Inside surface of the wall should be water resistant, smooth, and washable.
- Should not have ledges to collect dust and debris.
- Wall plates should be sealed to prevent insect entry and dust accumulation
- The edges of walls, especially at the base, are to be protected with sanitary bumpers or coved curbs to prevent the walls from chipping since chipped walls are bacteria and insect breeding places.
- Crevices at wall-ceiling junctions are to be eliminated to prevent insect or rodent harborage.
- Protective barriers recommended for areas where there is a high chance for potential for damage ( example Wall guards, Bollards )
- In wet areas blocks or tiles should be constructed using stacked bond rather than the running bond method to avoid moisture observation.
- Wall in a facility shall be designed without windows in processing, packing and storage area.
Ceiling: It is often neglected from sanitary design and construction perspective. Improperly constructed ceiling become a room for condensation, contamination, and eventually, increase the chance of food hazard incident. Some of the requirements of ceiling are:
- Should easy to clean, smooth and non-absorbent
- Good reflector of light
- Dropped ceilings are to be avoided in manufacturing areas
- Horizontal beams, pipes, and similar items are to be avoided over exposed products areas and food contact surfaces.
- Ceiling crevices are to be eliminated between pipes, supports hangers, etc. by caulking
Drain: Did you know? Floor drain proved to be the source of Listeria in food processing facility unless correctly designed, installed, and maintained, and continually cleaned and sanitized (H.L.M. Lelieveld). They basic performance expected from the drains are
- Drained floor
- No pounding or standing of water in product floor
- Designed to carry the maximum anticipated load to prevent any problem of flooding at your premises
- Adequate control measures should be in place to prevent insects and rodents from entering the processing area from drains.
- Drain channels shall be at least 15 cm from the floor and drainage channels should not place alongside walls
- P -traps to be used that create a water lock that keeps sewer gases out of the plant.
- Drain Channel Material –Stainless Steel can bear high temperatures, and it proves excellent in acid resistance. More importantly, it is anti-bacterial which is required for food processing facilities.
- Drain should be accessible for cleaning and application of sanitizer on routine basis
- Square bottom trench drains not recommended due to maintenance difficulty
- The grates constructed on the drain to withstand foot traffic and any other equipment movement.
Heating Ventilation Air conditioning System: Did you know? Sara Lee hot dog Listeria incident (USEPA, 2003) occurred due to airborne contamination. Maintaining clean and appropriate air pressure becomes very important. Air flow within a facility should flow from clean to dirty area. The thumb rule for food processing areas is a minimum 6±12 air turns per hours i.e. the volume of air in the room is changed 6±12 times per hour. A sensitive area like final processing area and packing highest filtered air pressure should be used. The ideal HVAC system:
- Cools and heats
- Filter for clean air
- Not from contaminated source
- Pressurizes the room
- Keeps ductwork out of the room.
The facility should have air tester to determine the microbial load of air entering into the facility. An air tester is even more important at ready to eat product handling facility
Sufficient amount of lighting is important in food processing or handling facility in view of safety, cleaning, sanitization, employee comfortability and related operations. Few criteria are:
- Without causing glare
- Preference should be given to lighting mounted on ceilings rather than on walls
- Formation of shadows to such an extent as to cause eye-strain or the risk of accident to any worker
- Either the light fixtures have an unbreakable cover or shatter proof bulbs
- Low UV emissions light should be considered in processing area to avoid fly attraction.
In general Metal halide lamps are widely used in food processing area due to intensities and distribution capability. USDA generally suggested range of lighting has been reproduced below:
|Food Processing Type||Lighting area||Illuminance (FC)|
|NELS /SIS/NTI Inspection||200|
|Pre – and Post-chill inspection||200|
Source: LEDs Magazine
Storage: Sufficient facilities to store raw material, packaging material, immediate products, finished product, chemical and etc., Basic expectations are:
- Separate storage area for raw , intermediate , and finished products, including chilled, frozen, packaging, cleaning chemical, equipment, and etc.,
- Access to material storage area should be controlled
- Cold stores to extent possible equipped with an automatic temperature control system to alert technical personnel when the temperature rises above the desired
- Floors in these areas capable of withstanding frequent cleaning, equipment movement.
- To extent possible racks to be made of chemical / corrosion resistant.
- Designed to enable stock rotation (FIFO) and batch traceability.
Personal facilities: Hand wash station, Rest Room, locker room, and break room should be designed with sanitation in mind. Did you know? Nearly around 25 % of foodborne outbreaks can be avoidable if adequate hand washing were accomplished (H.L.M. Lelieveld). Some of the important criteria are:
- Toilet areas are vented outside of the plant by exhaust fan
- Katsuyama (1993) stated that the minimum air flows 35 cubic feet of air per minute for each of the water closet or urinal
- Negative air pressure needs to be maintained at locker and restroom
- Recommended to use maze design so nothing has to be touched going in and out of the room.
- Should not open directly in food processing area
- Floor, Wall, Ceiling shall be in a match with another part of the facility.
- Hand wash sink should wall hung and water activated with knee , thigh or sensor
- Food operated no longer recommended due to perceived cleaning difficulties on undersides of petals.
- Adequate supply of cold and hot water to exercise hygienic practices
The handbook of hygienic control in the food industry –edited by H.L.M. Lelieveld