Surface cleaning is carried out as a wet or dry process depending on the soils present, the product, the process and the type of production equipment and typically refers to the following methods: dry cleaning, semi-dry cleaning, manual cleaning, soak cleaning and foam or gel cleaning.
Commonly refers to where no liquid detergents or disinfectants are used and where alcohol impregnated wipes or sprays and dry wipes are utilised. Used in environments where water use may lead to the growth and spread of pathogens and/or damage the quality and consistency of the product such as bread, pastry or biscuits etc., dry cleaning is also commonly used in packaging areas to ensure sensitive electrical and electronic equipment is protected.
Dry cleaning typically involves the use of hand scrapers, brushes, vacuum cleaners and air lines.
Semi-Dry cleaning usually refers to cleaning with disposable impregnated wet wipes or an alcohol spray and cloth. The use of impregnated surface wipes is ideal for cleaning items such as control panels and other sensitive electrical and electronic equipment. The wipes are usually impregnated with a detergent disinfectant solution. Because there is no need to wet them before use they are ideal for applications where water needs to be kept to a minimum. However, surface wipes have two disadvantages; they can only be used where light soiling is present and can also prove to be expensive if there are no rigorous internal controls on site.
Note: alcohol based disinfectants often contain a proportion of water and therefore still pose a risk to electrical components if directly sprayed.
Semi-dry, or damp, cleaning can also be undertaken with localised spraying of small volumes of detergent/disinfectant via e.g. trigger sprays. Liquids can be removed via wiping with a clean cloth or dry wipe and the surface can be re-sprayed if a separate disinfectant stage is required.
Manual cleaning refers to the cleaning process where the detergent is applied via a cleaning tool such as cloth, scouring pad or brush. Manual cleaning of machinery, equipment and surfaces is probably the most common method employed throughout the food manufacturing industry. Because manual cleaning is locally controlled by the operative, the risk of cross contamination can be significantly less than utilising physical energy input from medium or high pressure water. Other benefits include the relative low cost of the equipment required to carry out these tasks (buckets, brushes, cloths, scourers etc.). However, manual cleaning can be very labour intensive and extend the length of time needed to carry out a cleaning task efficiently and effectively. Manual cleaning will usually involve either a neutral detergent, a detergent disinfectant or a light/medium duty alkaline detergent.
The manual cleaning of machinery, walls, floors, doors, drains etc. can be very time consuming and will probably not achieve the results that can be achieved using a foam application method. However, in certain manufacturing and packaging environments manual cleaning is the only option. It must also be noted that although there can be a significant reduction in the generation of aerosols and overspray in comparison to medium or high pressure cleaning, cross contamination can still occur in various other ways, such as using dirty cleaning tools.
The failure to frequently change detergent solutions during manual cleaning can result in it becoming heavily contaminated, which in turn can rapidly spread bacteria across the surface.
Water/ detergent solution fed brushes can also be utilised to improve cleaning efficiency.
Soak cleaning refers to cleaning of items that are placed to soak in detergent solution for a period of time before physical action with a brush or pad and then rinsing with clean water. Soak cleaning of small items is essentially carried out in the same manner as domestic sink washing and is typically used for utensils, knives, small machine parts, blades, depositor parts, etc. The major advantage of soak cleaning is that it increases thermal and chemical contact time with the soiling, thereby helping to break it down more readily.
Alkaline or neutral detergents are typically used for soak clean applications although it isn’t uncommon to use caustic detergents for protein or carbonised soil, chlorinated detergents for stain removal and acid based detergents for removal of scale build up.
Foam cleaning refers to the cleaning process where the main detergent is applied as foam.
With increasing commercial and technical pressure placed on the food manufacturing industry, the time window and manpower required for cleaning has been squeezed and decreased. Foam cleaning was introduced during the last 30 years and has proven to be a very effective, efficient and popular method for cleaning factories and equipment. Along with the improvement in foam technology, such as long cling foams and quick break foams and the introduction of different types of foam detergents, it has become possible to apply foam cleaning to almost all types of environments and materials of construction.
Foam is created by mixing water, detergent and air together and applying it via a hose with a special nozzle or lance onto the surfaces and equipment. The foam detergent will typically be applied at 3 to 5%v/v, depending on the soil to be removed, materials of construction and water hardness. Gels are applied in the same way as foam detergents.
The main advantages of foam cleaning in comparison to manual cleaning are:
Although foam cleaning is used predominately in most food manufacturing sectors it is usually not suitable in areas such as bakery, pastry processing and packaging areas where the introduction of water and detergent can have a detrimental effect on the cleaning result. Foam cleaning may be successfully used in some areas of a Bakery, such as conveyor systems, but provisions should be made for water removal.
A common misconception of foam cleaning is that it negates the need for any type of physical action. Physical energy must be applied after suitable detergent contact time. The physical energy can be applied by either scrubbing with a brush or pad or by energy from a high or medium pressure water jet. In high care environments where a milder foam detergent and low/medium pressure systems are usually utilised it will probably be essential that scrubbing of equipment and surfaces takes place.
