Compressed air is used in a broad range of applications in the food processing industry. These applications include mixing of ingredients, cutting, sparging, drying of product, transporting and propelling food through processing systems, and packaging of final food product. In many of these applications, compressed air is in direct or indirect contact with food product. Impurities in the compressed air may contaminate the food and cause change of color and taste, reduced shelf life, and product recalls.
The perfect environment for microbial growth
Compressed air, which is generated on site by pulling in ambient air and compressing it, contains water vapor, particulate matter, oil vapor and droplets, and microorganisms such as bacteria, viruses, fungi and spores. (Atmospheric air typically contains 140 - 150 million dirt particles/m3 and can contain up to 100 million microorganisms/m3.) Contaminants, such as liquid oil, oil aerosols and oil vapor, can also enter compressed air as a result of leaks in worn seals, orifices and O-rings within the compressor. Since the compression process raises the temperature of the air, the air needs to be cooled before use. This process condenses water vapor into water aerosols and droplets. Water in the compressed air can produce rust and corrosion in the piping which can flake off and be carried downstream, contaminating the food product.
Water condensate, warm compressed air and dark conditions provide the ideal environment for growth of bacteria, spores and mold. These microbes travel through the entire compressed air system and are released at exit points where the air comes into contact with food, packaging, or food contact surfaces.
Safe Quality Foods (SQF) guidelines
Recently, Safe Quality Foods (SQF) released a 7th edition amendment. Section 10.5.7.1 states, "Compressed air used in the production process shall be clean and present no risk to food safety". Until now, the only devices capable of sampling compressed air systems for microbes were expensive, cumbersome, and required lengthy sampling times and extensive training.
Testing compressed air for microbes
The Parker Compressed Air Microbial Test Unit - CAMTU is the most cost effective solution for quickly and easily testing compressed air for microbes. The Parker CAMTU weighs less than one pound, is easily transported, requires no electrical connection and provides test results in approximately 20 seconds with minimal training required. The device includes connection tubing, a shut off valve and a specially designed pressure regulator and metering orifice. These matched components provide the exact amount of compressed air exposure required for each sampling. The petri dishes are pre-filled with specialized tryptic soy agar (TSA) and are designed to hold up to compressed air flow and pressure. TSA is used for the cultivation of a wide variety of microorganisms including most bacteria and mold spores.
For additional information, read this report on the comparison of the compressed air microbial testing unit to a standard method of bioaerosol sampling.
Watch this quick video to see how easy it is to test compressed air.
This post was contributed the Compressed Air and Gas Treatment Technology Blog Team, Parker Industrial Gas Filtration and Generation Division.