The US Department of Agriculture maintains oversight of food safety in the United States. Sub-branches oversee the various aspect of food production across different industries.
USDA Branches
Food Safety and Inspection Services (FSIS) – Assumes primary responsibility for approving any equipment used in plants processing eggs, meat, and poultry.
Agricultural Marketing Service (AMS) – Controls the approval process for equipment used by the dairy facilities they’re responsible for inspecting.
Food and Drug Administration (FDA) – Uses Current Good Manufacturing Processes (CGMPs) outlining the construction and cleanability of any food equipment used in food processing plants. They also developed a program evaluating equipment used in any Grade A Dairy Facilities.
A number of other organizations maintain standards for sanitary food equipment development.
Standard Governing Bodies:
3-A Sanitary Standards, Inc. – Funded by organizations from the dairy industry, various regulators, and equipment manufacturers.
The National Sanitation Foundation (NSF) – Outlines standards adopted by those in the retail and foodservice industry. In recent years they’ve begun offering their own input into proper standards for manufacturing food processing equipment.
The European Hygienic Design Group (EHEDG) – Oversees the approval of food processing equipment in Europe. They’ve published guidelines for designing and constructing any machinery used in food processing plants. American companies looking to sell their food processing equipment there need to ensure their products pass the testing guidelines established by this body.
How Does Oversight Work?
The governing bodies and regulatory agencies overseeing sanitary and hygienic design for food equipment have certain differences due to their sphere of influence. All agree in general on the need for prioritizing food safety above all else.
Many, like the 3-A Sanitary Standards, provide certifications designating that equipment meets the proper standards for a particular industry. All have their own systems of reporting violations and targeting any food equipment manufacturers seeking to find shortcuts that put the safety of the public at risk.
Any manufacturer caught falsifying approvals from the FDA or other oversight organizations run the risk of being shut down and permanently barred from the industry.
What Are the General Design Principles?
The central concern of any design principles should be the surfaces food could potentially come in contact with. They’re grouped into two categories:
- Contact Surfaces – Designed to be in direct contact with food products.
- Non-Contact Surfaces – Not meant to be in contact with any food products.
Contact Surfaces
Any surfaces intended to come into direct contact with any food should meet these requirements:
- Be smooth and impervious
- Contain no crack or crevice of any type
- Made of nonporous and nonabsorbent material
- Not be conducive to contamination
- Not react to any food product
- Resist corrosion
- Require no maintenance
- Be extremely durable
- Contain no toxins
- Be cleanable
Surfaces covered in any type of metal alloy or non-metal material must still meet the above standards. You should never see flaking, bubbling, chipping or any type of distortion regardless of factory environment conditions. Any modifications used during fabrication – like welding or soldering – should use appropriate materials and produce a surface meeting sanitary and hygienic design principles.
Materials Used
Different materials meet different requirements depending on the type of food processing machinery needed by a factory, facility, or retail environment. Some manufacturers incorporate antimicrobial coatings into their designs to improve safety. Any materials or surface coatings used should conform to the standard needed by that particular industry.
Metals:
Stainless Steel – The preferred metal of choice due to its resistance to corrosion and the durability it brings to various machine designs. Designers should account for the composition of nickel and metal in the material they choose. Certain combinations should only be used for more industrial purposes like pipe construction, not building food equipment.
Titanium – The cost prohibits the more wide-spread use of this metal. It’s also corrosion-resistant and long-lasting. You’ll often find it in stainless steel alloys used to build machines handling foods with a high level of acidity.
Platinum – Similar to titanium in providing higher quality but prohibited from more extensive industry-wide usage due to its cost.
Copper – Used primarily for equipment in the brewing and cheese industries. Should not be used with high-acid food as the acid residues tend to leach into the metal.
Aluminum – Often used for food processing machinery designed with a lighter weight in mind. It’s extremely susceptible to corrosion and becomes warped and cracked after a long period of use. Oxidizing cleaning products accelerate the decline of the metal. Most aluminum products designed for food contact must be coated with some sort of plastic coating to protect against this.
Carbonized metal and cast iron – Only used for cooking surfaces and frying equipment.
Non-Metals: 
Rubber and Plastic – Any materials used must meet specific standards outlined by 3-A Sanitary Standards, Inc. The FDA considers any products designed for multiple uses as an indirect food additive in some instances.
Ceramics – You’ll mostly see this material used in membrane filtration systems. Certain other products requiring wear resistance might also incorporate its use to some capacity.
Glass – Limited in use for food contact surfaces due to fears of breakage. Any glass products used must past tests ensuring its durability, resistance to shattering, and heat resistance. You’ll also see glass used as a way to provide a line of sight inside machinery or glass piping applications.
Paper – Typically used for gaskets in piping constructs designed to be taken apart on a daily basis. They’re often intended to be used only once.
Wood – Its porous nature makes it a very poor choice as a food contact surface. Most regulators restrict the use of wood in food service outside of cutting boards or butcher blocks.
Non-metals must meet the same cleanability and sanitary design standards required of metal. The lack of corrosive resistance and lower durability means that strict inspection and testing standards need to be in place to watch for the deterioration of products built with non-metal materials.
Standards for Surface Texture
Any alterations to surface materials like polishing, texturing, or grinding should be done only to produce a final finished surface that is:
- Smooth
- Free of crevices or any type of crack
- Meets all other sanitary standards
Recent methods adopted by the 3-A Sanitary Group outline industry standards on calculating an acceptable food contact surface. This involves determining the surface roughness average (Ra value) measured by an instrument called a profilometer. It measures the peaks and valleys of a seemingly smooth surface using a diamond-tipped stylus.
Machine Construction
Food equipment should be designed and constructed free of any sharp corners or crevices where bacteria could breed. The construction process should allow for easy assembly and disassembly for cleaning and inspection needs. Constructs like vessels, tanks, or chambers should be self-draining and provided access to a draining port with nothing getting in the way.
Screenshot via Food Safety Magazine
Any piping systems not meant to be taken apart should be angled downward for easy drainage. Modern food processing systems with piping systems built with a cleaning-in-place (CIP) design must be closely monitored to make sure it’s draining properly.
Other Considerations:
- Cover internal angles or design them to be rounded at a specific radius.
- Joints should be built with smoothness and durability in mind.
- Watch how connections to machinery are made. This includes items like thermometers, pipes, probes, or any other equipment. Attachments or other ancillary components should be sealed off from any potential contamination by food products or other leakages.
- Construct any covers or openings to provide protection for any food products against potential contamination. Make any openings lipped and cover them with a shoebox design. Construct the top rims of equipment to resist water or any other particles like dust.
Surfaces Not Designed for Food Contact
It’s possible for food to accidentally come into contact with surfaces like floors, doorknobs, or other parts of the food processing plant not intended for that purpose. Places like this provide a fertile breeding ground for bacteria like listeria to thrive if proper sanitation measures aren’t taken.
The surfaces should also be inspected for how well they conform to sanitary and hygienic design principles. They should still be made of a material that’s easily cleaned and suited to the types of products being manufactured.
Design tubular frameworks to be sealed. Avoid penetrating them with rivets, bolts, or studs. Crevices left behind by these binding materials allow micro bacteria to build and spread to different areas of a food processing plant.
Avoid having areas where dust can build up. Try to fabricate any equipment tops, shields, or covers at a 45-degree angle. Seal the base and avoid any type of hollow design. Following general food plant facilities best practices and controls will go a long way in ensuring the safety of food products produced, as well as plant workers.
How Should Installation Be Done?
Make sure equipment gets installed in a logical order designed to provide maximum protection against any type of cross-contamination. Leave ample space around equipment and between any piece of equipment and a wall to allow for a thorough cleaning.
Check for any places that might encourage rodents or insects to gather. It’s best to leave about four inches between a piece of equipment and the wall. Seal floor-mounted equipment to the floor, platform, or related pedestal. It should be at least six inches from the floor otherwise.
Seal table-mounted equipment to the tabletop or make sure it’s no less than four inches from the countertops.
Any perceived complexity in the concept of hygienic and sanitary design should be compared to the benefit obtained from using equipment designed for easy cleanliness and maintenance. It makes things easier for your labor force and provides long-term savings thanks to the payoff obtained from using well-designed equipment built for durability.
Sanitary and hygienic design helps equipment manufacturers and, subsequently, food processing plants, remain compliant with the latest regulations and recommended best practices. In addition to ensuring the safety of the food supply, sanitary and hygienic design principles simply make practical (and economic) sense.
