Food and Kitchen Odor: The Complete Guide

Cooking smells are supposed to be temporary, and the calls we get are all about the ones that were not. A curry from a previous tenant that is still in the kitchen six months later. A house that smells of fish every time the heating comes on. A rental that smells faintly of old frying no matter how thoroughly it is cleaned.

The thing all of those have in common is oil. This guide explains how cooking odor becomes permanent, where it goes, what each of the common cases needs, and why an extractor hood is so often the reason a kitchen never quite clears.

How a cooking smell becomes a permanent one

Cooking releases aromatic compounds and, whenever oil or fat is involved, aerosolized droplets of it. Those droplets travel with the warm air, cool, and condense onto surfaces: cabinet fronts and their tops, the ceiling, the walls, the extractor hood and everything within a few metres of the hob.

The result is a thin greasy film. It is often invisible until you wipe a section and see the difference. That film is the actual problem, because it is sticky, it accumulates, and it absorbs and holds the aromatic compounds of everything cooked afterwards. A kitchen with years of accumulated film smells of a composite of everything that ever happened in it, and it releases more strongly when the room warms up.

This is also why cleaning the surfaces people look at, the counters and the hob, achieves so little. Those get wiped constantly and hold almost none of it. The reservoir is above eye level and on vertical surfaces nobody touches.

The extractor hood, which is usually the reason

There are two kinds of extractor hood and the difference matters more than any other single factor in this subject.

A ducted hood pulls air through a grease filter and vents it outside. It removes the moisture, the grease and the smell from the building. A recirculating hood pulls air through a grease filter and a carbon filter and blows it back into the room. It removes some grease, some smell while the carbon is fresh, and nothing at all from the building.

Recirculating hoods are extremely common in apartments and in kitchens where ducting to an external wall was inconvenient, and the carbon filter in them is often original. Once that filter is saturated, which takes months rather than years, the hood is a fan that moves cooking vapour around the room. People run it diligently and reasonably assume it is doing the job.

• Check which type you have. If there is no duct going outside, it is recirculating.
• Change the carbon filter on a recirculating hood every six to twelve months. Most have never been changed.
• Clean the metal grease filters properly. They are usually dishwasher safe and usually filthy.
• Run the hood before you start cooking and for ten minutes afterwards, not just during.
• If you are dealing with a persistent kitchen smell in a property you own, converting to ducted extraction is the intervention with the largest long-term effect.

The specific cases people ask about

Different foods leave different problems, and the approach changes accordingly.

• Curry and heavily spiced cooking. Turmeric, cumin, fenugreek and asafoetida produce compounds that bind readily to the grease film and to soft furnishings, and they are persistent. This is the classic previous-occupant smell. It needs full degreasing of the kitchen including the ceiling, treatment of any carpet, curtains and upholstery within range, and often the ducting.
• Fish. The compounds involved, principally amines, are volatile and pungent and they settle into fabric quickly. Fish smell in a room usually clears with ventilation and degreasing far faster than curry. Fish that got into upholstery, or a fridge or freezer failure involving fish, is a much bigger job.
• Burnt food. The hardest of the three, because burning produces smoke, and smoke residue behaves like any other smoke: it condenses onto surfaces and works into porous material. A badly burnt pan can scent an apartment for weeks. Treat it as a small smoke event rather than a cooking one.
• Old grease. Years of accumulation without extraction. Needs mechanical work, degreasing, more than once, before any treatment, because treatment cannot get through the film to what is underneath.
• Fridge and freezer failure. Spoiled meat or fish after a power cut produces one of the worst smells we deal with and it soaks into the appliance liner and insulation. Sometimes the appliance is not worth saving, which we will tell you.
• Garbage, disposal and bin smells. Usually straightforward and usually not what people think: the smell is often in the cabinet the bin sits in rather than the bin itself.

Clearing a kitchen properly

1. Deal with the extraction first. Clean or replace the grease filters, replace the carbon filter if recirculating, and check the duct if there is one. Doing this last means recontaminating what you have cleaned.
2. Degrease from the top down. Ceiling, tops of wall cabinets, cabinet fronts, walls, the underside of the hood, light fittings, then work surfaces. A dedicated degreaser, not a general purpose spray, and change the water frequently.
3. Open and clean the interiors. Inside cabinets and drawers, especially those nearest the hob. Grease vapour gets into them every time they are opened while cooking.
4. Handle the soft furnishings. Curtains, blinds, any upholstery in an open plan space, and rugs. These hold a surprising proportion of the smell in an open plan kitchen and are frequently ignored.
5. Check the appliance seals and interiors. Fridge door seals, the interior of the microwave, the oven, and the extractor motor housing.
6. Treat what is left. If a kitchen has been used hard for years, degreasing gets you most of the way and leaves a baseline that will not shift, because the compounds have gone into the drywall paper and any unsealed timber. That is the point at which treatment is worth it.

Restaurants, apartments and shared buildings

Commercial kitchens are the same physics at a much larger scale, with the addition of a grease trap and a duct run that is a fire risk as well as an odor one. Grease trap smell specifically is a plumbing maintenance issue: the trap needs emptying on a schedule and the smell tells you that schedule has slipped. No amount of odor treatment substitutes for pumping it.

In apartments, cooking odor arriving from another unit is one of the more difficult problems to solve at the individual level. It travels through shared ventilation, plumbing penetrations, gaps around pipework and the corridor. Sealing gaps around pipes and under doors helps. Treating your own unit does not, because nothing in your unit is producing the smell.

For anyone living above a restaurant, the honest position is that the answer usually lies with the restaurant's extraction rather than with your apartment, and that is a building management or environmental health conversation. We can clear what has already absorbed into your property, and we will tell you it will return if the source has not changed.