Hygienically clean

15th of June 2010
Hygienically clean
Hygienically clean

Steam, dry ice and foam are among the methods of cleaning in hygiene-critical food preparation areas. But what advantages do these offer over traditional detergents and disinfectants, and do they have any downsides? Ann Laffeaty investigates.

Traditional methods of cleaning in food preparation areas tend to involve the use of chemicals and water. The market includes a whole hose of detergents and disinfectants that are designed to remove residual soiling from food surfaces and inhibit the growth of bacteria afterwards.

But detractors claim these method have their drawbacks. Not all antibacterial products kill on contact, for instance, but need to be left on the surface to take effect for a number of minutes. Some operatives will not wait the stipulated time which means bactericidal effect may be compromised.

There are also fears that micro-organisms can develop resistance to antibacterial products where these are in continuous use. The use of water can be a problem too, since water can interfere with electrical equipment and machinery. Surfaces also need to be completely dried afterwards to prevent any regrowth of bacteria in the damp, micro-organism conducive conditions.

So a number of alternative food preparation cleaning systems have been developed to address some of these concerns. But can these replace traditional food sector cleaning methods?

One of the emerging technologies in the food preparation area is that of dry-ice blasting. This is a form of abrasive blasting where dry ice - the solid form of carbon dioxide - is directed at a surface under pressure in order to clean it. The method uses a similar technique to that of sand blasting and leaves no chemical residues behind since dry ice vaporises at room temperature.

Among the companies that offers dry-ice blasting systems is Triventek. Key accounts director Craig Booth said: “If you want a cleaning technique that achieves similar results to sand-blasting, heavy chemicals or water - but you don’t want the downsides of abrasion, mess or interference with machinery – you would choose dry ice. The fundamental concept of dry ice cleaning is that the cleaning media actually disappears.”

Triventek has developed the Triblast-2 dry-ice blasting machine which is used in conjunction with dry ice pellets. These are supplied to the company in insulated boxes and resemble grains of rice, but maintain a constant temperature of -79°C.

The dry ice pellets vaporise to gas on impact and allow cleaning to be carried out in situ. This reduces downtime by eliminating the need to strip down and reassemble machinery parts, according to the company.

“With high pressure water systems, around 99 per cent of the material you collect is water that has been contaminated with the dirt you are cleaning away,” said Booth. 

“Our system has the advantage that it is dry. This means it involves no disposal costs; there are no electricity conductivity issues to contend with and there is no need to dry out the conveyer belts afterwards.”

Dry-ice cleaning technology has been around since the late 1970s according to Booth, but was originally used as a highly specialised and costly method of cleaning. “However the equipment has now come down dramatically in price and the dry ice pellets themselves are being more widely manufactured,” he said.

Although dry ice cleaning represents a larger initial investment than traditional cleaning methods, Booth claims it offers significant time savings which in turn provide cost benefits. “There is a reduction in the total job time since you don’t have to dismantle the equipment or clean up afterwards,” he said. “You also avoid the cost of using the water itself.”

Also becoming increasingly common in food preparation areas are steam cleaning systems. These are growing in demand since steam vapour is said to be able to kill germs and disinfect surfaces without the need for chemical disinfectants.

Steam is produced in a boiler that heats tap water to high temperatures, resulting in a low-pressure dry steam vapour. This is then applied to surfaces using insulated tools and accessories, and contaminants are released into water suspension where they can be removed either by wiping them away or by vacuum extraction.

Osprey Deepclean offers a range of steam cleaning machines for use in food preparation areas. International sales manager Markus Bast claims the process offers a number of advantages over traditional methods. “Most chemical disinfectants take several minutes’ contact time to achieve disinfection of the treated surface,” he said. “In practice this protocol is not always observed, and you will often find those responsible for cleaning will simply spray on the disinfectant solution and immediately wipe it off the surface.

“Steam, on the other hand, uses a combination of mechanical and thermal action to disinfect surfaces on contact, and this method can achieve very good results in food factories. The advantage here is that you only use a little water and after steam cleaning the surface is left completely clean and dry. In fact you can use steam cleaning equipment in dry environments.”

Another major benefit that steam cleaning offers over chemicals, says Bast, is that pathogens cannot become resistant to steam. “When a cleaning surface has been contaminated by pathogens such as E coli and Listeria which are susceptible to thermal disinfection, the steam action will rupture the outer membrane of the bacteria cell,” he said. “This means the pathogen is destroyed on contact. The cleaning process is then completed using vacuum extraction to leave the surface clean and dry.”

He said dry-ice blasting had its place in the food industry, but tended to be used for large-scale equipment restoration tasks and was generally carried out at infrequent intervals. “Dry-ice cleaning may be used in factories where the machinery is really dirty, but it cannot be used during the production run,” he said. “With steam cleaning methods, however, specialist heads have been adapted for in-line cleaning to allow continuous cleaning of the food belt for example.

“Dry-ice methods work very well and can be used to complement a steam cleaning regime, but dry-ice blasting is very expensive. Steam cleaning is less expensive, more versatile and more practical for regular on-demand cleaning.”

Foam cleaning systems are also frequently used in food preparation areas since these increase contact time of the detergent. The fact foams have been developed to cling to vertical surfaces also means walls can be cleaned and disinfected as well as food preparation surfaces.

Diversey’s food preparation range includes Enduro-power foam technology, an advanced foam cleaning system for kitchens that was originally developed for food factories.

“Extending the use of advanced foam cleaning to modern, larger kitchens is a very logical development and is applicable to all areas and surfaces in the kitchen,” said the company’s European portfolio manager kitchen care Carine Van der Sande.

“Advanced foam cleaning is definitely the way forward since it delivers superior cleaning performance at lower costs due to reduced labour.”

So foam, steam and dry-ice are being increasingly used in the food sector. But will they replace the need for traditional chemicals? Not according to chemicals manufacturer Evans Vanodine.
The company produces cleaning and sanitising products such as Est-eem, a non-tainting cleaner and sanitiser for use on work surfaces, floors, walls and equipment in the food and catering industries.

International sales manager Peter Thompson says the company also offers foam cleaners, but leaves technologies such as steam and dry ice to organisations with the facilities to develop the equipment.

“When correctly applied, steam and dry ice may be effective in a terminal disinfection role,” he said.  “However the demand for simple and effective cleaning before disinfection will never be replaced. Therefore the logic of a traditional one-stage formulated biocidal cleaning product is undeniable.”

Read more about new products in food preparation hygiene


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