Product-specific cleanrooms: moving away from large cleanrooms to small, local solutions

Yoghurt, bread, sausage, cheese, salads and drinks - more and more products are being filled and packed in sterile environments. Once, when the catchword ‘cleanroom¦ came up, most people thought of the large halls in microchip factories. However, now production under cleanroom conditions is increasingly finding its way into the food industry.

So-called ‘clean-label’ products promote themselves by advising consumers that they do not contain additives. It is the unpopular preservatives that are being cut from the recipes more than anything. “Less chemistry, more physics” is the philosophy that Martin Schüring from the Bremerhaven Institute for Food Technology and Bioprocess Engineering (BILB) is using to make this point. However, the manager of the F&E Innovation department knows there is another side to this coin - “By shying away from preservatives, food manufacturers have to keep microbiological threats at a greater distance from the product in order to achieve the desired shelf-life” - hence the growth of cleanroom manufacturing.

Fewer germs in the air

A clean - that means sterile - environment is the prerequisite for being able to relinquish preservatives. Every germ counts - especially when it comes to fresh products such as salads, pasta or sandwiches. Cleanrooms can be used to securely lock out bacteria and mould, the factors that cause food to spoil prematurely.

In the cleanroom a constant inlet of sterile air generates high pressure, which forces the impure air out of the production zone. Multilevel, high-efficiency particulate air filters can block even the most miniscule particles from the air stream.

The ISO 14644-1 standard defines cleanroom classes 1 to 9 and determines how many particles of which size are allowed per cubic metre of air - the lower the cleanroom class, the greater the level of purity.

Whilst a chip factory requires a very high level of purity, cleanrooms between ISO class 5 and 8 are the norm for food manufacture. ISO class 5 already represents a load of less than 1 germ/m³ - in other words, practically sterile.

It isn’t always necessary to furnish complete production halls as cleanrooms, which can make a large dent in the budget. Instead, some manufacturers are opting for room-in-room concepts. Clever divisions make it possible to set up zones in the production area with different grades of purity.

The highest level of purity is only used where it is really necessary, like in the production of sliced bread: laminar flow tunnels come into operation for this process. The boxes, which are sealed on three sides, generate a horizontal or vertical stream of pure air to provide the necessary high pressure. Once the baked goods have been removed from the oven, they are cooled using sterile air and cut whilst still in the tunnel. They only leave the local cleanroom once they have been packed.

Every cubic centimetre of pure air is expensive. The aim of the plant construction firm is therefore to configure this on as small a scale as possible. Machines that might be impure are kept outside of this sterile zone.

The drinks industry in particular has tried to reduce the cleanroom to an absolute minimum over the years. Restricted-access barriers (RABs) and isolators are the focus of current developments. The compact ‘hygiene minis’ are not only cheaper to build but also to operate. The area around an isolator is so strictly marked out that employees are allowed to wear normal-hygiene clothing. In modern, cold aseptic filling facilities, only the bottle track still runs inside the isolator, which is separated from the surroundings to form a thick chamber. In this process, non-heated fruit juice flows directly into the bottles.

RABs, on the other hand, are not hermetically sealed: An air barrier is generated from the high pressure inside the housing and protects the heart of the machine - the sterile area. While production is taking place, it can only be accessed from the outside using glove boxes. These are placed at critical points along the filling machine. All other areas can be reached via external doors without air locks.

Organic cultivation in ‘pure culture’ is a new aspect of cleanroom technology. The Japanese technology group Fujitsu goes one step further as part of its ‘Kirei Yasai’ (clean vegetables) program. Salads are being cultivated on 2000 m² under cleanroom conditions in a former semiconductor plant. Perfect environmental control means the harvested salad should remain fresh for two weeks at 10°C and display low levels of nitrate.

At the upcoming Anuga FoodTec event taking place from 24-27 March 2015 in Cologne, Germany, visitors will be able to meet the following cleanroom technology suppliers: Anton Hurtz GmbH & Co KG, B-Hygienic - PolySto bvba, BLU Ewelina Kasprzyk, Dastex Reinraumzubehör GmbH & Co KG, Ecolab Europe GmbH, Endress + Hauser Messtechnik GmbH + Co KG, FF Fischer Planning LTD, FIMINOX SPA, Friedrich Sailer GmbH, Fromfroid SA, Heraeus Noblelight GmbH, Index-6 Ltd, Maschinenbau Helmers GmbH, Niebling Techn. Bürsten GmbH mrca GmbH, Peschl Ultraviolet GmbH, PNR Deutschland GmbH, Industriespritzdrüsen, SPX Flow Technology, TRAVAGLINI SPA, Vikan A/S and Wiedemann GmbH. They will be exhibiting in the ‘Food Safety/Hygiene Technology’ sector of Anuga FoodTec.