Mould control in commercial refrigerators in humid climates

Why mould grows in a refrigerator

Mould needs moisture, food and time. A refrigerator in humid weather supplies all three: condensation and defrost water provide moisture, spills and crumbs provide food, and dark folds that nobody cleans provide time. Some moulds grow slowly at chilled temperatures, so a cabinet that is cleaned rarely will eventually show growth even when temperature is correct.

Spores come in on produce, bread, cardboard packaging and the air itself, so they cannot be kept out entirely. The aim is to make surfaces too clean and dry for them to settle.

Where to look

• Inside the folds of door gaskets, especially on the hinge side and the bottom.
• Shelf corners, shelf supports and the joint between walls and floor.
• Around the drain hole and inside drain lines.
• The drip tray in the machine compartment.
• Strip curtains and door frames in cold rooms.
• Ceiling panels and panel joints in cold rooms, where warm air leaks in.
• Under shelf mats and liners that are rarely lifted.

Cleaning mould safely

• 1. Empty the affected area and check food stored there. Discard food with visible mould according to your food-safety plan.
• 2. Isolate power if cleaning near fans, lights or the controller.
• 3. Wash surfaces with warm water and detergent to remove the mould and the film it grows on. Use a soft brush in folds and corners.
• 4. Rinse, then apply a food-contact sanitiser at label dilution. For stubborn mould, a properly diluted chlorine-based product can be used on non-metal surfaces as the label allows, then rinsed.
• 5. Dry every surface completely, including gasket folds.
• 6. Clean the drain line and drip tray at the same time — they reseed the cabinet if left.

When cleaning is not enough

Mould that has grown into the material of a gasket leaves black stains that do not lift and returns within days. Replace that gasket. The same applies to porous shelf mats and heavily stained strip curtains. In cold rooms, mould that keeps returning along a panel joint can mean warm humid air is leaking in or moisture has entered the panel — a job for the installer or a refrigeration contractor.

Prevention habits

• Clean gaskets weekly and dry the folds; in the monsoon, check them twice a week.
• Wipe spills at once, especially sugary and protein-rich ones.
• Cover food and remove cardboard cartons before storage; cardboard carries spores and holds moisture.
• Rotate stock so nothing sits forgotten at the back.
• Keep doors shut and seals working to limit humid air entering.
• Keep air vents and the evaporator fan clear so air circulates and surfaces dry.
• Control room humidity where possible; air-conditioned stores see less mould than open shopfronts.

Musty smells

A musty smell is often the first sign of mould before it is visible. Do not cover it with fragranced products, which can taint food. Find the source — drain line, drip tray, gasket folds, under shelf mats or a forgotten container — and clean it. Baking soda placed in the cabinet afterwards can absorb residual odour.

During shutdowns

Switched-off refrigerators grow mould fastest of all. Before any shutdown longer than a day or two, clean, dry and leave doors propped slightly open. Many monsoon-season closures end with a mouldy interior simply because doors were shut on a damp cabinet.

Safety notes

Wear gloves when cleaning mould and avoid stirring dry spores into the air; work with damp cloths. Never mix chlorine products with acids or ammonia. Isolate power near electrical parts. Leave evaporator housings, drain heaters and anything near the refrigeration circuit to a technician, particularly on units using flammable hydrocarbon refrigerants.