How to Clean a Freezer Room or Cold Room

Cleaning a cold room or a freezer room is a two-stage procedure: first you clean (remove visible dirt and organic matter with detergent) and then you sanitize (kill the microorganisms left on the already clean surface). Reversing the order is pointless: no sanitizer works on a surface with grease or protein residue on top. Cold does not sterilize either; it only slows microbial growth, and there are microorganisms such as Listeria monocytogenes that multiply at refrigeration temperatures.

What the regulations require

If food is stored in the room, cleaning stops being a good practice and becomes a legal obligation. The framework below is Colombia's, enforced by the INVIMA (the food and drug agency) and the health departments; food safety rules in the United States (FDA) and other countries follow the same logic of a written sanitation plan, controlled temperatures and trained staff.

• Resolution 2674 of 2013 (Ministry of Health and Social Protection). Article 26 requires every establishment that manufactures, stores, transports or sells food to have a written sanitation plan with four minimum programs: cleaning and sanitizing, solid waste management, integrated pest control and potable water supply. The cleaning and sanitizing program must state in writing the agents and substances used, their concentrations or method of use, contact times, the equipment and tools required and the frequency.
• Storage and transport. The same resolution requires controlled temperature, humidity and air circulation, with calibrated instruments and periodic verification; for frozen products it sets -18 °C (0 °F) or lower, and for transport, temperature logging systems all the way to the final destination.
• Food handlers. Uniforms must be light-colored so dirt shows, with closed, waterproof, low-heel footwear and zippers instead of buttons. Training in hygiene and good practices must be at least 10 hours a year.
• Decree 60 of 2002. Promotes the HACCP system and regulates its certification. Under that approach, cleaning and sanitizing is a prerequisite: the foundation on which critical control points rest, not a critical point in itself.

What to do with the product during cleaning

The room must be empty before any chemical is applied. There are three ways to handle it, and none of them allows improvisation:

• Schedule the cleaning at the inventory low point, when the room is naturally low on product. It is the cheapest option, which is why it pays to set the calendar in advance.
• Move the product to an alternate room that is already at temperature. The transfer must be quick and documented, with temperature records before and after.
• Use temporary equipment. A refrigerated container placed next to the plant works as a backup cold room during the intervention and avoids breaking the cold chain.

What you cannot do is clean with product inside, not even covered: detergent and sanitizer aerosols reach surfaces you would not expect.

Personal protective equipment for the operator

You are working with concentrated chemicals in a closed, cold space, sometimes with pressurized water. At a minimum the operator needs waterproof coveralls or a suit, long-cuff chemical-resistant gloves, wraparound safety goggles or a face shield, non-slip boots with safety toe caps and respiratory protection when fogging or spraying. If it is a freezer room and the work is done cold, add thermal clothing and limit exposure times by rotating staff.

Two operational warnings: never mix chlorine products with acids or ammonia (toxic gas is released), and never work alone inside a closed room.

Step-by-step procedure

1. Empty the room and relocate the product as planned.
2. Shut down and lock out the refrigeration unit with a lockout-tagout procedure so nobody energizes it during the intervention. De-energize the interior lighting as well if it is not sealed.
3. Open the doors and remove the strip curtains so the room rises to ambient temperature. Sanitizers lose effectiveness at low temperatures, and detergents do not dissolve grease well when cold.
4. Defrost and remove the ice from the evaporator and the surfaces. Never chip ice with metal tools: you will puncture the coil.
5. Dry sweeping and collection of solid waste from the floor, channels and drains, before wetting anything.
6. Pre-rinse with water from ceiling to floor to carry away loose dirt.
7. Apply detergent to ceilings, walls, floor, shelving and doors, respecting the contact time on the technical data sheet. Soft-bristle brush on panels and painted surfaces; a stiffer brush only on the floor.
8. Rinse until all detergent residue is gone. A sanitizer applied over leftover detergent is neutralized.
9. Sanitize at the concentration and contact time defined in the sanitation plan, without leaving puddles.
10. Clean the critical points separately: door gaskets and seals, handles, rails, condensate tray and drain, evaporator diffusers and PVC strip curtains.
11. Dry and ventilate. Residual water turns to ice as soon as the unit starts.
12. Inspect and repair. Surface scratches on the panel are touched up with food-contact-grade paint; a puncture that exposes the insulation requires replacing the panel or installing a sanitary cove, because wet insulation gets contaminated and loses capacity.
13. Restart, stabilize the temperature and verify with a calibrated thermometer before loading product again.
14. Record. Date, person responsible, products used, concentration, contact time and verification result. Without a record, as far as an inspection visit is concerned, the cleaning never happened.

Which products are used, and why

No brands are recommended; active ingredients are chosen according to the type of soil and the surface material:

• Alkaline detergent: dissolves grease and protein. It is the workhorse in meat and dairy rooms.
• Acid detergent: removes mineral scale and salts. It is alternated with the alkaline one, never mixed.
• Sodium hypochlorite: a broad-spectrum, low-cost sanitizer. It loses effectiveness with organic matter and corrodes stainless steel if left too long or used too concentrated.
• Quaternary ammonium: leaves a residual effect on the surface and is not very corrosive, but it is inactivated by anionic detergent residue, so it requires a careful prior rinse.
• Peracetic acid and hydrogen peroxide: keep good activity at low temperature and break down into harmless residues. They are the most used when the room temperature cannot be raised much.

All of them must have a safety data sheet available, be approved for use in the food industry and be stored in an area separate from the products. It pays to rotate active ingredients to avoid selecting resistant microorganisms, and always to check compatibility with the panel coating (polyester, PVDF, plastisol, PET or stainless steel).

How often to clean

Each company sets the frequency in its sanitation plan according to the risk of the product. This is the scheme usually taken as a starting point:

Beyond the scheduled frequency, there are triggers that require immediate cleaning: product spills, broken packaging, pest entry, strange odors, an equipment failure that allowed thawing and a change in the type of product stored.

Frequently asked questions

Do I have to switch off the refrigeration unit to clean?

Yes. It is switched off and locked out, both for the operator's safety and for effectiveness: detergents and sanitizers are formulated to work above 10 °C (50 °F) and perform much worse at room temperature settings.

Can I use a pressure washer?

With care. High pressure creates aerosols that spread microorganisms and can damage seals, insulation and the evaporator coil. When one is used, keep pressure low and flow high, and never aim it at the refrigeration unit or the electrical connections.

How do I verify that the cleaning worked?

Visual inspection is necessary but not sufficient. Objective verification is done with surface swabs sent to a laboratory or with ATP measurements, and the results are kept as support for the sanitation plan.

How often should a refrigerated container used as a cold room be cleaned?

The same criteria apply as to a fixed room: the frequency depends on the product and the risk. The practical difference is the T-bar floor: its channels collect residue and must be swept and rinsed in every cycle, because they are the path the cold air circulates through.

What temperature should a freezer room reach?

For frozen product, the reference is -18 °C (0 °F) or lower. We expand on the topic in what temperature a freezing system should run at, and if you need a backup cold room during the cleaning shutdown, see our refrigerated containers.