Food Processing Industry: Cleaning of Vertical surfaces

Vertical surfaces can also get dirty. Spillages, leaking sprays, maintenance and human contact lead to an unclean sight. Walls, exterior of tanks, glass windows, etc, are the common objects that need regular cleaning for simple reasons like:

a) Risk to the food being processed even exterior of vessels and walls contribute to the total microbial load in the highly sensitive food processing area and can pose as a possible source of contamination of food under processing.

b) Aesthetics – Clean plant and clean exterior of equipment add to the aesthetics to the overall cleanliness.

c) More than anything, cleanliness helps boost the moral of the employees.

It is very easy to clean any horizontal surface (either manually or mechanised). However, cleaning becomes difficult for lean vertical surfaces using the traditional methods of cleaning. Also intricate places are mostly not approachable by manual means and are often left unclean or partially cleaned. Traditionally, mechanised cleaning for such case is often considered to be high pressure cleaning, which definitely is not the only technique for cleaning. Further, it has its own limitations like relatively low effective impact and aerosol formation.

The answer is cleaning with low pressure foam/gel cleaning technique. It is all the more relevant in the food and beverage processing industry since the application of foam/gel does not generate aerosols, which is very important to prevent cross contamination.

The technique involves application of the cleaning chemicals as gel/foam on the surface and leaving it in contact with the surface for acting upon the soils. This is then rinsed off using water and the surface comes out shining and clean.

Foam/Gel Cleaning:

Unlike high-pressure jet cleaning, foam/gel cleaning technique works at a low operating pressure, as low as 3bar. The technology involves proper mixing of detergents, water and compressed air to deliver optimal foam/gel structure that is fairly stable and ensures sufficient contact time with the soil on the surface to be cleaned. If the foam/gel layer is very thick or wet (Fig. A), it will run off too quickly. That would not give adequate contact time leading to inadequate chemical action on the soil and would result into inefficient cleaning and higher product consumption. The proportional mixture of foam/gelling detergent, water and air should be such as to generate very stable foam/gel structure that gives contact time of approx. 10 minutes on the soiled surface (Fig.A). This foam/gel structure breaks at a slow pace that releases the detergent solution onto the soiled surface. The surfactants in the formulation allow better penetration of the detergent solution into the soil and loosen it from the surface.

The foam/gel detergent ideally should contain soil suspending and anti re-deposition agents so that when the foam/gel is rinsed off with water, these agents bind the soil tightly so that it is not re-distributed to other surfaces throughout the plant and cause re-contamination.

Advantages of foam/gel cleaning:

• Effective cleaning of intricate, non-approachable places
• Low operating pressure, labour requirement and operating cost
• Safe for operators
• No aerosol formation eliminating risk of cross contamination, as aerosols are the medium of transportation for microbes (Fig. B).
• Temperature drop is not as fast as high pressure, if cleaning with warm detergent solutions.

Drop in temperature in High Pressure / Low Pressure

There are various formulations of these new generation foam/gelling detergents available these days that vary from general-purpose detergent-cleaner to chlorinated detergent cum sanitizer and odourless QUAT based detergent sanitizers that clean and sanitise the surface at one go. The selection of the product and cleaning programme depends upon the type and amount of soil build up and the surface to be cleaned.

While foam/gel detergents have existed for a long time, this technique has seen a significant technology shift with the introduction of “EnduroPower” range of film cleaning technology. The range offers long “wet period” and thus a much longer contact with the surfaces being cleaned without the breakdown of the film. The film breaks rapidly with the use of water and rinses off easily.

The foam/gel cleaning systems also have options for selecting equipment from the basic mobile pressure pot type of foam/gel generating machine with an air compressor unit to a top-end customised central, de-centralised or PLC controlled automatic system comprising of a main station and number of satellite units.

The equipment shown in Fig. C is the very basic system made completely from high-grade stainless steel and mounted on trolley for easy maneuverability. It is easy to operate and once adjusted, does not require readjustment. The benefit of such system is that the equipment can be moved as and where the water and air lines are available and can be connected or disconnected. The system has an option to choose from a pressurised tank as well as a tank with atmospheric pressure. One has to ensure proper safety in case of a pressurised system.

The state-of the-art system comes with an option of wall mounting as well as mounting on trolley for mobility. It also comes with or without an air compressor. The high end completely customised system with main station and satellite units gives enough flexibility of carrying out rinsing, cleaning and disinfecting activities simultaneously. It also allows using different products at different satellite units at the same time.