UV in professional kitchens - grease elimination and odor control

Keeping the hood clean and hygienic allows to prevent and eliminate annoying problems of efficiency of the entire ventilation system and at the same time ensures the maintenance of a low fire risk.
Beside fire risk, problems associated with odors produced by cooking food, are wide spreading and represent an increasingly issue. 
The substances responsible mainly include fat-acids, aliphatic and aromatic hydrocarbons, aromatic amines and aldehydes. The type and quantity of pollutants emitted depend mainly on what kind of product has been cooked, the cooking methods and the means used for cooking. There are many ways to filter odors, but there are no specific rules on “olfactory pollution”. 
Odor is a complex phenomenon to understand  not just for the wide range of potentially odorous substances, but mainly because the ability of a substance to be perceived by our olfactory system depends on different aspects that are both objective (volatility, water solubility, etc) that subjective 
(physiological and psychological of the observer) but can also involve the environment (temperature, pressure, relative humidity of the air, speed and direction of the winds). This means that the same substance, at a distance from the source, is perceived differently by different people. 
The odorigenic compounds can constitute an important friction point between the restaurant / hotel /catering and the surrounding environment, since smells are able to spread in large areas without that anybody can carry out resolutive interventions to contain it avoiding the exaxperation of the people involved. 
UV technology is the most effective way to eliminate greases in kitchen hoods. 
The ideal ventilation system in a large professional kitchen should include a portion containing UV lamps, possibly together with Titanium Dioxide (TiO2) and Silver Salts filtration systems. For the maintenance of cleanliness and a prolonged effect on the elimination of odors, it is often necessary to consider the application of UV lamps in combination with Ozone emission.
UV lamps are mercury vapor bulbs that emit the specific wavelength of the C band (UV-C), capable of breaking the bonds of fat compounds by breaking them down into simpler molecules 
(H2O, CO2, etc.) creating what is scientifically called "cold combustion". Some of these lamps are made of a special transparent quartz at a wavelength of 180 nanometers, which is able to "transform" the molecules of Oxygen into molecules of Ozone (O3).  The properties of ozone are both ultra clean and persistent over time; ozone is in fact a highly unstable molecule, which tends to re-transform into oxygen soon. Nevertheless, the application in the kitchens’ ventilation channels is very effective in eliminating odors precisely because ozone is able to "follow" the smells along the ductwork, eliminating them before they are released outside. 
As soon as ozone comes into contact with an organic matter, an oxidation reaction is triggered.  Basically, molecules are oxidized, they are transformed into harmless molecules, thus eliminating any form of bad smell. Furthermore, Titanium Dioxide has a specific action on the elimination of VOC and NOC (organic and non-organic flying compounds) as it acts as a catalyst capable of degrading numerous organic compounds. By exploiting its properties we are able to destroy the deposited organic compounds and activate its self-cleaning and de-polluting capabilities. When applying this type of system, the only precaution is to mount it downstream of mechanical filters that micronize fat molecules like common mesh or labyrinth filters.  The UV technology therefore offers excellent results in the management of fat fumes and in the treatment of odors, with great benefits on several fronts. 
  • substantial elimination of odors •
  • reduction of grease deposits in smoke extraction systems •
  • less use of chemicals to sanitize •
  • better cleaning and overall hygiene •
  • greater safety against fire hazard •
  • significant reduction in maintenance costs •
In addition to those just listed, great advantages can be found especially with the combination of different technologies, achieving improvements for the management of the entire ventilation in kitchens. 
There are various ways of applying UV, UV + Ozone and UV + Ozone + Titanium dioxide filters ​Once the specific situation has been analyzed, it is important to consider these essential points: 
  • The optimum air speed must not exceed 2.5 m / s 
  • The application of UV systems is as efficient as it is closer to the source of the smoke. Being able to mount the UV systems immediately after the hood in fact enables not only to keep the surfaces clean from the initial stages, but the air "free" from fat compounds leaves no deposit in any part of the ventilation duct. 
  • Applied in the hood, it is necessary to ensure that the UV , system is positioned so that the filters shield the outflow of the rays towards the operator and provide a microswitch for system easy OFF. 
  • Using ozone, it is always advisable to add a pressure switch that automatically switches off the UV system in the event of a stop in ventilation to guarantee operators’ safety. 
  • In the case of outlets at street level and the application of UV + Ozone systems, it is important to make sure that the Ozone has completely "turned back" into oxygen before the air comes out in the street. Usually a few meters of channel are required for this to happen, otherwise the application of a second UV-ONLY system at the outlet can guarantee its complete elimination, UV-C rays "help" the O3 molecules to turn into O2. 
  • The application of UV, UV + Oz and UV + Oz + Titanium Dioxide combines perfectly with activated carbon filters. Not only these technologies fight odors effectively together, but carbon filters are greatly improved from the application of Ultraviolet rays, which increase their durability and efficiency. 


Ultraviolet rays are electromagnetic waves which are part of light. Electromagnetic waves are divided into three main wavelength bands, expressed in nanometers, nm: Ultraviolet rays (UV) 100-400 nm Visible rays (light) 400-700 nm Infrared rays (IR) 700-800,000 nm UV rays are in turn identified in three bands:

  • UV-A (315-400 nm) with tanning properties;
  • UV-B (280-315 nm) con proprietà terapeutiche e di sintesi della vitamina "D";
  • UV-C (100-280 nm) with germicidal properties.

UV-C rays (100-280 nm) have a strong germicidal effect and reach their maximum efficacy at the 265 nm wavelength. The germicidal effect of UV-C radiation covers bacteria, viruses, spores, fungi, moulds and mites; this is mainly due to the destructive effect of the UV-C rays on their DNA, which damage their reproductive system and prevent them from replicating.

Bacteria, Viruses, Spores, Fungi, Mould, and Mites are all sensitive to, and can therefore be eliminated with, UV-C light. Mircrobes cannot acquire resistance to UV-C light, unlike that which occurs using chemical disinfectants and antibiotics. UV rays are ecological. Polluting the environment is inevitable using normal disinfectants. Directly inhaling the vapours, or swallowing food products contaminated by any contact with said chemical disinfectants, can also give rise to a number of serious risks. In cases where chemical disinfectants cannot be eliminated (food, pharmaceutical, healthcare industries, etc.), using ultraviolet rays for disinfection allows a reduction in their use, with considerable economic savings and greater care for the environment, while maintaining and almost always improving the level of disinfection. UV-C light devices can be installed in environments and on machinery and be programmed to maintain the same level of disinfection day and night, guaranteeing ideal hygiene conditions, without highs and lows. On the contrary, chemical disinfectants are effective only during their actual use. Using LIGHT PROGRESS equipped luminaires, operating costs are negligible; it could be said that “LIGHT PROGRESS” UV-C systems do not require maintenance except for the normal replacement of the lamps. The cost/benefit ratio is considered excellent; the devices are both powerful and long-lasting. Hence the elimination of germs using UV-C technology is low-cost and highly effective compared to (or in combination with) other systems.

UV-C light genuinely works if properly applied and with the necessary precautions. The difference between a quality project, and an application that fails to bring the desired results, lies in the degree of knowledge about the subject, and level of experience acquired over time. Light Progress has been developing successful projects worldwide since 1987, and has built a client portfolio consisting of important companies in all fields requiring certified hygienic conditions to produce quality products and services.