Foam cleaning refers to the cleaning process where the main detergent is applied as foam and Gel cleaning where the main detergent is applied as a gel. Gels can also be aerated during application; this is called a mousse. Foam or gel application is followed by a water rinse; this can be of low medium or high pressure.
Foam and Gel Cleaning
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 has proven to be a very effective, efficient and popular method for cleaning of rooms and equipment. The improvement in foam technology, such as long cling foams, and the introduction of different types of foam detergents have made it a process that can be used, with benefit, in many situations.
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 and water hardness. The main advantages of foam and gel cleaning in comparison to manual cleaning are:
The detergent solution can be applied to large and difficult to reach areas in a short period of time
An extended detergent contact time between the soil and the detergent
A reduction in the time of clean
Less manpower required
Control of detergent use
Safer application of hazardous detergents
A common misconception of foam and gel cleaning is that it negates the need for any type of physical action (such as scrubbing with a brush or scourer). Physical energy must be applied after suitable detergent contact time. The physical energy can be applied by either scrubbing or by energy from a water jet; typically either high or medium pressure.
Washdown System
A washdown system provides the hygiene operative with an efficient tool for rinsing away soil and detergent. The water jet provides a degree of physical energy to a surface that assists in the removal of the soil. The higher the pressure of the system the higher the impact energies available.
Medium pressure systems operate at typically 20 bar with a flow rate at the nozzle of 30 litres/min. This gives very similar cleaning energies to a high pressure systems operating at 70 bar and with a flow rate at the nozzle of 15 litres/min. Low pressure systems operate at typically 5 bar with a nozzle flow rate of 40 to 50 litres/min.
Both medium and high pressure systems provide sufficient cleaning energy to remove most soiling if the correct foam or gel detergent has been used. With low pressure rinsing however, this is not the case and it is essential that surfaces are scrubbed prior to rinsing.
All washdown systems whether low, medium or high pressure will cause overspray which can lead to cross contamination if no controls are put in place; however high pressure systems also create aerosols which add another vector of cross contamination.
Cleaning tools are a major source of contamination. Cleaning tools and their management generally receive low priority; this was aptly demonstrated in a food industry wide survey by Campden BRI which showed that of all cleaning tools tested 35% were Listeria positive. The correct choice of tools, the management of cleaning of tools and the designation of specific tools for different purposes (usually identified by a colour coding system) is essential.