Agriculture

Sanitary Design of Equipment

Equipment and utensils used in food processing should be designed, constructed and installed to:

function as intended
allow effective cleaning and sanitation
prevent contamination by either physical, chemical or biological hazards

Contaminated equipment can transfer pathogenic bacteria to food products. This could result in a foodborne illness outbreak or recall of your food product.

Equipment Sanitary Design Principles

According to the American Meat Institute, there are 10 principles for the sanitary design of equipment:

1. Cleanable to a microbiological level. Equipment should be designed to prevent bacterial access, survival, growth and reproduction on both food contact and non-food contact surfaces. Removing all food materials is critical for effective cleaning and sanitizing of equipment. Ideally, surfaces should be smooth with no pores, crevices, sharp corners or angles, because bacteria can survive and grow in hidden areas.

2. Accessible for inspection, maintenance, cleaning and sanitation. All parts of the equipment must be readily accessible for inspection, maintenance, cleaning and sanitation without using tools. Disassembly and assembly will result in the best sanitation. Ex: quick release clips on shields and guards, sanitary peg legs and open bases.

3. Made of compatible materials. Materials used for equipment must be completely compatible with the product, environment, cleaning, sanitizing chemicals and the methods of cleaning and sanitation. Materials must be smooth, non-corrosive, non-absorbent, non-toxic and be able to withstand repeated cleaning and sanitizing. Structural materials should not contribute to product contamination. Materials will vary with different manufacturing facilities to endure dry vs. wet cleaning and the harshness of the environment. Ex: brine tanks, extreme heat from ovens or extreme cold from blast freezers.

4. No product or liquid collection. Equipment should be self-draining to ensure liquid does not collect or condense on the equipment. Where appropriate, drainage is connected directly to drains. Horizontal surfaces must be avoided. Surfaces should always slope to one side. If a slope is not possible, there must be a procedure in place to minimize pooling and help draining. Ex: use a squeegee or wiping procedure.

5. Hollow areas hermetically sealed. Hollow areas of equipment such as frames and rollers must be eliminated, wherever possible, or permanently sealed. Bolts, studs, mounting plates, brackets, junction boxes, nameplates, end caps, sleeves and other such items must be continuously welded to the surface and not attached by drilled and tapped holes.

6. Sanitary operational performance. During normal operations, the equipment must not contribute to unsanitary conditions or the harbouring and growth of bacteria. Avoid screw threads, rivets and bolts. These can trap food and create areas that are hidden and difficult to clean.

7. Validated cleaning and sanitizing protocol. Procedures for cleaning and sanitation must be clearly written, designed and proven effective and efficient. Chemicals recommended for cleaning and sanitation must be compatible with the equipment and the manufacturing environment. When upgrading existing equipment or installing new equipment, work with equipment vendors to ensure sanitary design and/or have a third party expert review design before installation. Validating (PDF 260 KB) your cleaning procedure must be done to ensure proper sanitation. This is accomplished by laboratory analyses of samples over a period of time.

8. No niches. Equipment parts should be free of niches such as pits, cracks, corrosion, open seams, gaps and poor welds. These types of niches can harbour food or soil possibly becoming microbial or allergen niches. Ex: there should be no tack or spot welds. Welds should be smooth, continuous and ground smooth to prevent niches.

9. Hygienic compatibility with other plant systems. Equipment design should ensure hygienic compatibility with other equipment and systems, such as electrical, hydraulics, steam, air and water. Ex: leaking of hydraulic fluids onto food contact surfaces or into product; corrosive or damaging fluids onto improperly covered electrical wiring.

10. Hygienic design of maintenance enclosures. Maintenance enclosures and human machine interfaces such as push buttons, valve handles, switches and touch screens, must be designed to ensure food product, water or product liquid does not penetrate or accumulate in, or on, the enclosure or interface. Physical design of the enclosures should be sloped or pitched to avoid use as storage area.

Guidelines on Equipment Design

There are guidelines for equipment design that provide general information to anyone proposing to construct a new food processing establishment, extensively remodel an existing food processing establishment or convert an existing building into a food processing establishment.

The following diagram shows you an example of bends and rolled edges:

bends and rolled edges

For detailed guidelines that contain examples and pictures follow these links:

Equipment Repairs

Equipment repairs must be sanitary and permanent. If temporary repairs are necessary, keep track of them by:

recording the incident
establishing your corrective action, including the time needed to make it a permanent sanitary repair
recording the closing of your corrective action

Remember that temporary repairs compromise food safety.

Benefits of Implementing Sanitary Design of Equipment

quicker and effective cleaning
less chemical use
lower labour costs associated with cleaning and sanitation
easier access for inspection and maintenance
better overall efficiency

Major concern: Listeria monocytogenes

A common microbiological contaminant Listeria, can become established in areas where cleaning and sanitizing is ineffective. There are eight identified species of Listeria:

L. dentrificans
L. grayi
L. innocua
L. ivanovii
L. murrayi
L. seeligeri
L. welshimeri
L. monocytogenes

Only Listeria monocytogenes is a known human pathogen. If equipment becomes contaminated with L. monocytogenes, the bacteria can move out of their established areas and onto the surfaces of the equipment when it is in operation. Food products travelling on the equipment will then spread the bacteria into subsequent processing areas.

Some common areas where L. monocytogenes is found:

hollow conveyor rollers
standing water
condensate (the liquid product from condensation)
equipment framework
unsanitary welds
unsuitable ledges