Odour transfer problems are not infrequent among the fruits and vegetables stored in cold storages. The odours are usually VOCs (volatile organic compounds). These compounds are transferred either through air currents or diffusion from their source and are adsorbed or absorbed by other products. Any food product which does not have its characteristic flavor and aroma, is definitely not appealing to consumers and is not considered salable. Foods that are known to be significant sources of VOCs include potatoes, onions, oranges, apples, pears, blueberries, garlic, ginger root, strawberries etc. These should never be stored along with the produce vulnerable to odour transfer. Foods that are known to be vulnerable to odour transfer are carrots, cranberries, peppers, kiwifruit etc.
ODOUR CONTROL METHODS:
Ventilation: Odour within an enclosed space can be treated by ventilation with ambient air from outside sources. Effective room ventilation can even be carried out within refrigerated spaces as long as the duration of ventilation is relatively brief and the temperature within the space does not increase more than a few degrees. However, this short term solution is not usually completely effective, either because the ventilation duration is too short or because the odour recurs from the source in a relatively short time.
Packaging: Another solution is enclosing the products in packaging materials that prevent the passage of VOCs. As long as the packages remain intact, odour transfer through the package is virtually impossible. Some flexible polymeric packaging materials provide a lesser barrier to passage of VOCs than others, such as LDPE (low density polyethylene), they are all reasonably effective.
Activated Carbon Air Filter Systems: Activated Carbon is a micro crystalline carbon that has been manufactured to produce extensive internal porosity, thereby providing an extensive surface area with the capability of adsorbing VOCs from the air. When air containing odorous VOCs is passed through a container of granular activated carbon, the VOCs are attracted to and held onto the surface walls of the micro pores. Air leaving a correctly operated container is essentially free of VOCs and is therefore odor free. Activated Carbon Air Filter Systems can be used in warehouses or cold storages. The time time required for activated carbon to become saturated with VOCs may vary from few weeks to months or a year or more. After saturation, the system will no longer remove odour.
Ozone Generators: Ozone is a highly reactive molecule with formula O3. It controls odour from VOCs and other chemicals by oxidizing them to non-odorous components. Because ozone is unstable, it must be generated onsite using an ozone generator. Ozone generators have been used successfully to eliminate ammonia odour in warehouses. However, because of the potential for ignition and/or explosion, it is necessary to locate ozone generators outside the room and conduct the ozone into room through a hose or duct. Ozone is less effective at freezing temperatures and may cause objectionable flavor changes to foods high in lipids.
Nonetheless, the best option is to not store the odour vulnerable products with the odour emanating products.
