A tour around companies in the beverages and foodstuff industries clearly indicates the extensive use of compressed air and the therefore associated importance for the manufacturing process. Contaminations in the air, such as e.g. micro-organisms, mineral oils, oils and particles, are a real problem and must be removed or reduced by compressed air processing and treatment. This is executed in order to protect consumers and to ensure a safe and cost-efficient production process.
There are no internationally valid laws and guidelines especially intended for the use of compressed air in foodstuff areas. General recommendations and specifications can be taken from DIN ISO 8573-1 as well as the guidelines and recommendations based on the VDMA (Germany) and BCAS (UK).
In can be generally said that the manufacturer themselves demand a high quality for compressed air such as e.g. oil-free and germ-free. This is crucial, since the (EC) No 178/2002 Ordinance clearly places the obligation on the manufacturer to create or generate a safe product. Verification of compliance by implementing continuous measurement (24/7), also with regard to the voluntary HACCP concept or the operating preventive programme (OPRP), is also an important issue.
A wide variety of products as well as different machines and tools are required in the production of foodstuff and beverages, also pneumatic devices among others. Compressed air is mostly utilised here as control air i.e. as a pneumatic actuator for the control of grippers or valves. The materials of the pneumatic devices must comply with stringent requirements, such as being corrosion resistant, non-toxic and non-absorbent. The requirements for the compressed air itself especially depend on whether they come into direct contact with the food or not.
Compressed air pressure rarely comes into direct contact with the food when utilised for controlling a process although optimum compressed air processing remains important. Contaminations in the compressed air can accelerate the wear on the components and cause jamming in the components. Retaining the quality of the compressed air and an optimal design can therefore minimise downtimes and energy costs as well as preventing product contamination.
The condition of the final product must remain unchanged when packing and filling products. Beverages and food must therefore be treated very gently and there cannot be any resulting contamination. This means that compressed air utilised in this area must be oil-free and germ-free. So-called sterile air is required for processes in the packaging and filling food sector e.g. with deep withdrawal for beakers, thermal shaping of other packaging, inflating of packaging and filling liquid products. Compressed air is also utilised to blow out incorrect products or for cleaning of packaging materials.
Compressed air is also required in the beverages industry for, among other things, when PET bottles are used in filling processes. The bottles are inflated by a so-called stretch blowing process with compressed air. In addition, compressed air is generally used for cleaning the bottles, contamination such as dust can be removed as one example. Bottles are sealed with bottle tops in breweries, which are transported with compressed air. If compressed air is hereby contaminated with, then this subsequently reduces foam formation for the beer. This clearly demonstrates to which extent compressed air can have important effects on the sensory characteristics of the product.
Compressed air has additional applications in bottle sorting plants or when applying labels.
Many raw materials are treated, processed and transported in the food and beverages industries. Loose foodstuff such as granules, rice, cereals, sugar or coffee are transported in silos and tanks. The general rules for food transport state, among other things, that food may only be conveyed in designated, marked transport containers which are subjected to special hygiene requirements. Compressed air is often utilised for unloading and therefore comes into direct contact with the food. The previous measures for the containers will be invalidated when the compressed air is contaminated and thereby results in contamination. Dry compressed air is also particularly important for dry, loose foodstuff because otherwise lumps can occur.
This does not only apply for raw materials, rather more the end and intermediate products in the manufacturing process must also be conveyed from one process stage to the next. For example, not only the ingredients for chocolate but also the cocoa mass produced are conveyed pneumatically. A so-called pigging technology is utilised to push them out of the piping which also requires compressed air in order to push the pig.
Compressed air utilised in the manufacturing and treatment processes for foodstuff must always be oil-free and germ-free, as the compressed air comes into direct contact with the product. A corresponding compressed air processing is therefore required e.g. with a sterile filter for direct product contact Since there are no requirements in place for monitoring the compressed air, the manufacturers are responsible. Continuous monitoring of the compressed air quality ensures process safety and reduces incorrect production. This can easily occur, for instance in the context of ice cream production. Compressed air is blown into the base ice cream mass to make it creamier. If the compressed air does not have this necessary purity class, then the ice cream consistency is negatively affected.
Compressed air is utilised in additional foodstuff processes, among other things for cooling down bakery products and chocolate, blowing away dough and chocolate residue, spraying and glazing of dough-based products as well for coating potato products.
In addition, compressed air can be used for cleaning, blowing out shapes, for CIP cleaning of production plants or systems or for washing fruits and vegetables. Compressed air is hereby routed into the water so that it moves and achieves better washing effects.
Mechanical processes are not the only important element in food manufacturing, biotechnological processes, so-called fermentation processes, are also important. This process is disrupted by foreign organisms, which is why it is imperative that process-foreign organisms are removed. The materials involved and the application utilised must therefore be sterile. This of course also applies for the compressed air, whereby a sterile filter is often utilised for treating it. Compressed air is utilised, for example, for the ventilation of seasoning in brewing processes, for the production of nitrogen or for mixing and transporting yeast during the fermentation process.